The present invention relates to a method for the synthesis of cyclic depsipeptides, in particular emodepside, involving specific carboxylic acid group protecting tags.

Emodepside (cyclo[(R)-lactoyl-N-methyl-L-leucyl-(R)-3-(p-morpholinophen yl)lactoyl-N-methyl- L-leucyl-(R)-lactoyl-N-methyl-L-leucyl-(R)-3-(p-morpholinoph enyl)lactoyl-N-methyl-L-leucyl) is an anthelmintic drug that is effective against a number of gastrointestinal nematodes. Its molecular structure which is depicted below can be described as a cyclic octadepsipeptides, a depsipeptide being a peptide in which one or more of its amide groups are replaced by the corresponding ester groups. On a technical scale emodepside may be obtained by derivatization of the naturally occurring substance PF1022A in which two hydrogen atoms are exchanged for morpholine rings.

(Emodepside) WO 93/19053 Al (EP 0 634 408 Al) discloses a compound of the general formula:

wherein A is benzyl group which has suitable substituent(s) or phenyl group which may have suitable substituent(s), A ^a is benzyl group which may have suitable substituent(s) or phenyl group which may have suitable substituent(s), B and D are each lower alkyl, C is hydrogen or lower alkyl, and a pharmaceutically acceptable salt thereof.

WO 2005/055973 A2 discloses transdermally applicable agents containing cyclic depsipeptides and/or praziquantel, in addition to the production thereof and to the use thereof for fighting against endoparasites. Combinations of emodepside and praziquantel or epsiprantel and also 1,2- isopropylideneglycol as endoparasiticides are disclosed in WO 2006/094664 Al.

WO 2006/053641 Al relates to the use of endoparasiticidal depsipeptides for producing pharmaceuticals for preventing vertical infection with endoparasites.

The total synthesis of, amongst others, PF1022A and its derivatization are discussed in the review article "Cyclodepsipeptides: A Rich Source of Biologically Active Compounds for Drug Research" by Sivatharushan Sivanathan and Jiirgen Scherkenbeck, Molecules 2014, 19, 12368-12420; doi:10.3390/moleculesl90812368. For several cyclodepsipeptides total syntheses both in solution and on solid-phase have been established, allowing the production of combinatorial libraries. In addition, the biosynthesis of specific cyclodepsipeptides has been elucidated and used for the chemoenzymatic preparation of nonnatural analogues. The review article also summarizes the recent literature on cyclic tetra- to decadepsipeptides, composed exclusively of a-amino- and a- hydroxy acids.

In the synthesis of polypeptides a solid phase strategy has the advantage of easy separation of the reaction products, whereas a liquid phase strategy has the advantage of homogenous reaction conditions. A hybrid approach is a tag-assisted strategy where compounds having a tag group are easily separated from untagged molecules.

In this respect, JP 2000/044493 Al discloses a protecting group for synthesizing a compound library which consists of compounds capable of bonding with a compound to be protected in 1 : 1 ratio, having a single molecular structure and also having >=500 molecular weight, and consists of 3,4,5-tris-(n-octadecyloxy)benzyl alcohol, 3,4,5-tris-(n-octadecyloxy)benzyl chloride or methyl 3,4,5-tris-(n-octadecyloxy)benzoate.

EP 2 003 104 A2 relates to a reagent for organic synthesis with which a chemical reaction can be conducted in a liquid phase and unnecessary compound(s) can be easily separated at low cost from the liquid phase after completion of the reaction. The reagent for organic synthesis which is depicted below is reported to reversibly change from a liquid-phase state to a solid-phase state with changes in solution composition and/or solution temperature, and is for use in organic synthesis reactions.

Ri to R5 may be the same or different, and represent hydrogen, halogen, alkyl group with a carbon number of 1 to 30 which may have a substituent group, alkoxyl group with a carbon number of 1 to 30 which may have a substituent group, aryl group with a carbon number of 1 to 30 which may have a substituent group, acyl group with a carbon number of 1 to 30 which may have a substituent group, thioalkyl group with a carbon number of 1 to 30 which may have a substituent group, dialkylamino group with a carbon number of 1 to 30 which may have a substituent group, nitro group, or amino group; and at least two of Ri to R5 are groups with a carbon number of 18 to 30, and X represents a reagent active site having one or more atoms selected from the group consisting of a carbon atom, oxygen atom, sulfur atom, and nitrogen atom. The publication "Tag- Assisted Liquid-Phase Peptide Synthesis Using Hydrophobic Benzyl Alcohols as Supports" by Yohei Okada, Hideaki Suzuki, Takashi Nakae, Shuji Fujita, Hitoshi Abe, Kazuo Nagano, Toshihide Yamada, Nobuyoshi Ebata, Shokaku Kim, and Kazuhiro Chiba, The Journal of Organic Chemistry 2013, 78, 320-327; doi: 10.1021/jo302127d; reports that a soluble tag-assisted liquid-phase peptide synthesis was successfully established based on simple hydrophobic benzyl alcohols, which can be easily prepared from naturally abundant materials. Excellent precipitation yields are reported to be obtained at each step, combining the best properties of solid-phase and liquid-phase techniques. This approach is reported to be able to be applied efficiently to fragment couplings, allowing chemical synthesis of several bioactive peptides. The publication "A Novel Protecting Group for Constructing Combinatorial Peptide Libraries" by Hitoshi Tamiaki, Tomoyuki Obata, Yasuo Azefu and Kazunori Toma, Bulletin of the Chemical Society of Japan 2001, 74, 733-738; doi http://dx.doi.org/10.1246/bcsj.74.733; discloses 3,4,5- tris(octadecyloxy)benzyl alcohol, HO-Bzl(OCi8)3 which was prepared from gallic acid and stearyl bromide. Using conventional step-wise elongation, N,C-protected peptides, Fmoc-AA _n -...-AAi- OBzl(OCi8)3, were synthesized. The substituted benzyl esters were selectively cleaved by a treatment with 4 M hydrogen chloride in ethyl acetate to give Fmoc-AA _n -...-AAi-OH and HO- Bzl(OCi8)3. Thus, the substituted benzyl group is reported to be effective for the protection of C- terminal carboxyl groups in liquid-phase peptide synthesis. Because the substituted benzyl group has a moderately high molecular weight, Fmoc-AA _n -...-AAi-OBzl(OCi8)3 is reported to be easily purified by size- exclusion chromatography; all protected peptides were reported to be eluted in the void fraction of a Sephadex LH-20 gel-filtration column. The combination of the carboxyl- protecting group Bzl(OCi8)3 with simple purification by the gel-filtration is reported to give a novel route for constructing combinatorial peptide libraries in the solution phase.

WO 2017/116702 Al relates to a cyclic depsipeptide compound or a pharmaceutically or veterinarily acceptable salt of the following formula:

By way of example, a compound with the designation 7-34A as depicted below shows an EC50 value between 0.1 μΜ and 1.0 μΜ in an in vitro test against microfilaria of Dirofilaria immitis:

(7-34A of WO 2017/116702 Al)

The present invention has the object of providing an improved synthetic route to emodepside and related cyclic depsipeptides. Another object of the invention is to provide novel depsipeptides which may be synthesized using this route.

This object is achieved by a method according to claim 1 and depsipeptides according to claim 22. Advantageous embodiments are the subject of the dependent claims. They may be combined freely unless the context clearly indicates otherwise.

Accordingly, the present invention provides a method for the synthesis of cyclic depsipeptides according to the general formula (I) from depsipeptides according to the general formula (II):

(Π) (I) wherein B is an amine protecting group and A is a carboxylic acid protecting group, the method comprising the steps of: - deprotecting the amine group which is protected by the B group, thereby obtaining a deprotected amine group; deprotecting the carboxylic acid which is protected by the A group, thereby obtaining a deprotected carboxylic acid group; condensation of the deprotected amine and carboxylic acid groups, thereby obtaining the cyclic depsipeptide (I) whereby x and y are, independent of each other, 0, 1 or 2 with the proviso that x+y > 1 (preferably, x and y are 1) and Rl, R2, R3, R4, R5, R6, R7, R8, R9, RIO, Rl l and R12 each, independent of each other, represent hydrogen, straight-chain or branched Cl-C8-alkyl, in particular methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, hexyl, isohexyl, sec -hexyl, heptyl, isoheptyl, sec-heptyl, tert-heptyl, octyl, isooctyl, sec-octyl, straight- chain or branched halogenated C1-C8 alkyl, in particular fluorinated sec-butyl, hydroxy-Cl-C6- alkyl, in particular hydroxymethyl, 1 -hydroxy ethyl, Cl-C4-alkanoyloxy-Cl-C6-alkyl, in particular acetoxymethyl, 1 -acetoxy ethyl, Cl-C4-alkoxy-Cl-C6-alkyl, in particular methoxymethyl, 1- methoxy ethyl, aryl-Cl-C4-alkyloxy-Cl-C6-alkyl, in particular benzyloxymethyl, 1- benzyloxy ethyl, mercapto-Cl-C6-alkyl, in particular mercaptomethyl, Cl-C4-alkylthio-Cl-C6- alkyl, in particular methylthioethyl, Cl-C4-alkylsulphinyl-Cl-C6-alkyl, in particular methylsulphinylethyl, Cl-C4-alkylsulphonyl-Cl-C6-alkyl, in particular methylsulphonylethyl, carboxy-Cl-C6-alkyl, in particular carboxymethyl, carboxy ethyl, Cl-C4-alkoxycarbonyl-Cl-C6- alkyl, in particular methoxycarbonylmethyl, ethoxycarbonylethyl, Cl-C4-arylalkoxycarbonyl-Cl- C6-alkyl, in particular benzyloxycarbonylmethyl, carbamoyl-Cl-C6-alkyl, in particular carbamoylmethyl, carbamoylethyl, amino-Cl-C6-alkyl, in particular aminopropyl, aminobutyl, Cl- C4-alkylamino-Cl-C6-alkyl, in particular methylaminopropyl, methylaminobutyl, C1-C4- dialkylamino-Cl-C6-alkyl, in particular dimethylaminopropyl, dimethylaminobutyl, guanidino-Cl- C6-alkyl, in particular guanidinopropyl, Cl-C4-alkoxycarbonylamino-Cl-C6-alkyl, in particular tert-butoxycarbonylaminopropyl, tert-butoxycarbonylaminobutyl, 9-fluorenylmethoxycarbonyl- (Fmoc)amino-Cl-C6-alkyl, in particular 9-fluorenylmethoxycarbonyl(Fmoc)aminopropyl, 9- fluorenylmethoxycarbonyl(Fmoc)aminobutyl, C2-C8-alkenyl, in particular vinyl, allyl, butenyl, C3-C7-cycloalkyl, in particular cyclopentyl, cyclohexyl, cycloheptyl, C3-C7-cycloalkyl-Cl-C4- alkyl, in particular cyclopentylmethyl, cyclohexylmethyl, cycloheptylmethyl, benzyl, substituted benzyl, phenyl, phenyl-Cl-C4-alkyl, in particular phenylmethyl which may optionally be substituted by radicals from the group consisting of halogen, in particular fluorine, chlorine, bromine or iodine, hydroxyl, Cl-C4-alkoxy, in particular methoxy or ethoxy, Cl-C4-alkyl, in particular methyl.

The protective groups A and B may be orthogonal in that way that when the B group is deprotected, the A group is stable; however, it is also an embodiment of the present invention that A and B are deprotected simultaneously.

In the method according to the invention it has surprisingly been found that cyclic depsipeptides (I), in particular emodepside and closely related structures, can be synthesized in high overall yields.

After deprotection the amine and carboxylic acid groups are reacted to form a peptide bond. Suitable coupling agents together with a base such as Ν,Ν-Diisopropylethylamine include PyBOP (benzotriazol-l-yl-oxytripyrrolidinophosphonium hexafluorophosphate), BOP ((Benzotriazol-1- yloxy)tris(dimethylamino)phosphonium hexafluorophosphate), BOP-C1 (Bis(2-oxo-3- oxazolidinyl)phosphinic chloride), EDCI (l-Ethyl-3-(3-dimethylaminopropyl)carbodiimide), DEPBT (3-(diethoxyphosphoryloxy)-l,2,3-benzotriazin-4(3H)-one), HATU (1- [Bis(dimethylamino)methylene]-lH-l,2,3-triazolo[4,5-b]pyridi nium 3-oxid hexafluorophosphate), HBTU (2-(lH-benzotriazol-l-yl)-l,l,3,3-tetramethyluronium hexafluorophosphate) and, most preferred, T3P® (Propylphosphonic anhydride, 2,4,6-Tripropyl-l,3,5,2,4,6-trioxatriphosphorinane- 2,4,6-trioxide, PPACA).

In one embodiment of the method according to the invention x is 1, y is 1, Rl , R4, R7 and R10 are methyl, R6 and R12 are methyl, R5 and Rl l are, independent of each other, straight-chain or branched Cl-C4-alkyl or straight-chain or branched halogenated Cl-C4-alkyl and R3 and R9 are, independent of each other, benzyl or substituted benzyl. According to one embodiment of the preferred invention, R3 and/or R9 are p-morpholino substituted benzyl.

According to an embodiment of the present invention, A is acid-labile whereas B is labile to hydrogenolysis. Accordingly, it is an embodiment of the present invention to provide a method for the synthesis of cyclic depsipeptides according to the general formula (I) from depsipeptides according to the general formula (Ila):

wherein Y is an amine protecting group and X is a carboxylic acid protecting group, the method comprising the steps of: deprotecting the amine group which is protected by the Y group in the presence of an acid, thereby obtaining a deprotected amine group; deprotecting the carboxylic acid which is protected by the X group via hydrogenolysis, thereby obtaining a deprotected carboxylic acid group; condensation of the deprotected amine and carboxylic acid groups, thereby obtaining the cyclic depsipeptide (I)

In the method according to this embodiment it has surprisingly been found that cyclic depsipeptides (I), in particular emodepside and closely related structures, can be synthesized in high overall yields.

The term "hydrogenolysis" is to be understood in its broadest sense and is explicitly not limited to a reaction with gaseous and/or molecular hydrogen, although this is one embodiment of the present invention. Suitable catalysis are Pd, Pd/C, Pt, Pt/C.The term "hydrogenolysis" is also ment to include reactions where hydrogen is formed in situ or only formal and where hydrogenolysis reactants such as hydrazine or diimid etc. are employed.

In one embodiment of the present invention, X is a substituted or unsubstituted -CH2-Aryl group. According to one embodiment, X is selected out of the group benzoyl (Bn), 4-methoxy-benzoyl (PMB), 3,4-dimethoxybenzoyl (DPMB), 4-phenyl-benzoyl (PPB), 2-naphthylmethyl (Nap), Benzyloxymethyl acetal (BOM).

In one embodiment of the present invention, Y is t.-butyloxycarbonyl (Boc), trityl (Trt), p- methoxybenzyl carbamate (Moz) or p-Nitrobenzyl carbamate (PNZ). Most preferred Y is Boc. In another embodiment of the method according to the invention the depsipeptide according to the general formula (Ila) is obtained from precursors according to the general formulas (IV) and (III):

R

(IV) (III) (Ila) by: in precursor (IV), deprotecting the amine group which is protected by the PG2 group in the presence of a base, thereby obtaining a deprotected amine group; in precursor (III), deprotecting the carboxylic acid which is protected by the PG3 group in the presence of an acid, thereby obtaining a deprotected carboxylic acid group; condensation of the deprotected amine and carboxylic acid groups, thereby obtaining the depsipeptide (Ila); wherein Rl to R12, X, Y, x, and y have a meaning as defined above (in particular, x and y may be 1), PG2 is an amine protecting group and PG3 is a carboxylic acid protecting group. The deprotection and condensation methods may be the same as outlined in connection with the reaction of compounds (Ila) to (I) above.

Preferably the precursor according to the general formula (IV) is obtained from precursors according to the general formulas (VI) and (V):

(VI) (V) (IV) by: in precursor (VI), deprotecting the amine group which is protected by the PG4 group in the presence of a base, thereby obtaining a deprotected amine group; condensation of the deprotected amine group of precursor (VI) and carboxylic acid group of precursor (V), thereby obtaining the precursor (IV); wherein R7 to R12, X and x have a meaning as defined above (in particular, x may be 1), PG2 has a meaning as defined above and PG4 is an amine protecting group. The deprotection and condensation methods may be the same as outlined in connection with the reaction of compounds (II) to (I) above.

It is also preferred that the precursor according to the general formula (III) is obtained from precursors according to the general formulas (VIII) and (VII): -lo

(VIII) (VII) (III) by: in precursor (VII), deprotecting the amine group which is protected by the PG5 group in the presence of a base, thereby obtaining a deprotected amine group; condensation of the deprotected amine group of precursor (VII) and carboxylic acid group of precursor (VIII), thereby obtaining the precursor (III); wherein Rl to R6, Y and y have a meaning as defined above (in particular, y may be 1), PG3 has a meaning as defined above and PG5 is an amine protecting group. The deprotection and condensation methods may be the same as outlined in connection with the reaction of compounds (II) to (I) above.

It is also preferred that the precursor according to the general formula (VI) is obtained from the esterification of a precursor according to the general formula (IX) with X-LG:

(IX) (VI) wherein RIO to R12 and X have a meaning as defined above and PG4 has a meaning also as defined above and LG is a leaving group. The protection or tagging of the carboxylic acid group in (IX) may be effected using standard procedures, LG will often be halogenide, especially chloride. Alternatively LG can be -OH, then standard condensation protocols will often apply.

It is also preferred that the precursor according to the general formula (VII) is obtained from the esterification of a precursor according to the general formula (X) with PG3-OH:

(X) (VII) wherein R4 to R6 and y have a meaning as defined above, PG3 also has a meaning as defined above and PG5 also has a meaning as defined above.

It is also preferred that precursors (III) and (IV) are identical.

It is also preferred that R3 and R9 are identical, Rl and R7 are identical, R2 and R8 are identical, R4 and RIO are identical, R5 and Rl 1 are identical and R6 and R12 are identical.

According to an alternative embodiment of the present invention, A is base-labile whereas B is acid-labile. Therfore accordingly an alternative embodiment of the present invention present invention provides a method for the synthesis of cyclic depsipeptides according to the general formula (I) from depsipeptides according to the general formula (lib):

(lib) (I) wherein PG1 is an amine protecting group and TAG is a carboxylic acid protecting group, the method comprising the steps of: deprotecting the amine group which is protected by the PG1 group in the presence of a base, thereby obtaining a deprotected amine group; deprotecting the carboxylic acid which is protected by the TAG group in the presence of an acid, thereby obtaining a deprotected carboxylic acid group; condensation of the deprotected amine and carboxylic acid groups, thereby obtaining the cyclic depsipeptide (I)

The TAG group comprises a moiety Aryl-0-(CH2) _n - with Aryl representing an aromatic moiety and n being > 13, x and y are, independent of each other, 0, 1 or 2 with the proviso that x+y > 1 (preferably, x and y are 1) and Rl, R2, R3, R4, R5, R6, R7, R8, R9, RIO, Rl l and R12 each, independent of each other, represent hydrogen, straight-chain or branched Cl-C8-alkyl, in particular methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, hexyl, isohexyl, sec-hexyl, heptyl, isoheptyl, sec-heptyl, tert-heptyl, octyl, isooctyl, sec- octyl, straight-chain or branched halogenated C1-C8 alkyl, in particular fluorinated sec -butyl, hydroxy-Cl-C6-alkyl, in particular hydroxymethyl, 1 -hydroxyethyl, Cl-C4-alkanoyloxy-Cl-C6- alkyl, in particular acetoxymethyl, 1 -acetoxyethyl, Cl-C4-alkoxy-Cl-C6-alkyl, in particular methoxymethyl, 1 -methoxyethyl, aryl-Cl-C4-alkyloxy-Cl-C6-alkyl, in particular bcnzyloxymcthyl, 1 -bcnzyloxycthyl, mcrcapto-Cl-C6-alkyl, in particular mcrcaptomcthyl, C1-C4- alkylthio-Cl-C6-alkyl, in particular methylthioethyl, Cl-C4-alkylsulphinyl-Cl-C6-alkyl, in particular methylsulphinylethyl, Cl-C4-alkylsulphonyl-Cl-C6-alkyl, in particular methylsulphonylethyl, carboxy-Cl-C6-alkyl, in particular carboxymethyl, carboxyethyl, C1-C4- alkoxycarbonyl-Cl-C6-alkyl, in particular methoxycarbonylmethyl, ethoxycarbonylethyl, C1-C4- arylalkoxycarbonyl-Cl-C6-alkyl, in particular benzyloxycarbonylmethyl, carbamoyl-Cl-C6-alkyl, in particular carbamoylmethyl, carbamoylethyl, amino-Cl-C6-alkyl, in particular aminopropyl, aminobutyl, Cl-C4-alkylamino-Cl-C6-alkyl, in particular methylaminopropyl, methylaminobutyl, Cl-C4-dialkylamino-Cl-C6-alkyl, in particular dimethylaminopropyl, dimethylaminobutyl, guanidino-Cl-C6-alkyl, in particular guanidinopropyl, Cl-C4-alkoxycarbonylamino-Cl-C6-alkyl, in particular tert-butoxycarbonylaminopropyl, tert-butoxycarbonylaminobutyl, 9- fluorenylmethoxycarbonyl(Fmoc)amino-Cl-C6-alkyl, in particular 9- fluorenylmethoxycarbonyl(Fmoc)aminopropyl, 9-fluorenylmethoxycarbonyl(Fmoc)aminobutyl, C2-C8-alkenyl, in particular vinyl, allyl, butenyl, C3-C7-cycloalkyl, in particular cyclopentyl, cyclohexyl, cycloheptyl, C3-C7-cycloalkyl-Cl-C4-alkyl, in particular cyclopentylmethyl, cyclohexylmethyl, cycloheptylmethyl, benzyl, substituted benzyl, phenyl, phenyl-Cl-C4-alkyl, in particular phenylmethyl which may optionally be substituted by radicals from the group consisting of halogen, in particular fluorine, chlorine, bromine or iodine, hydroxyl, Cl-C4-alkoxy, in particular methoxy or ethoxy, Cl-C4-alkyl, in particular methyl.

In the method according to the invention it has surprisingly been found that cyclic depsipeptides (I), in particular emodepside and closely related structures, can be synthesized in high overall yields using hydrophobic carboxylic acid protecting groups TAG. These groups can render the molecules to which they are bound ("tagged" molecules) insoluble in polar solvents such as methanol. Hence, the tagged molecules can be precipitated out of a reaction mixture and the tagging group itself, after deprotection, can also be separated using this technique. Furthermore, the hydrophobic tagging group allows tagged molecules to be soluble in unpolar solvents such as dichloromethane.

The deprotection of the amine group by removing the protection group PGl can be performed using standard base-assisted procedures such as treatment with a piperidine solution in dichloromethane. Likewise, the deprotection of the carboxylic acid group by removing the TAG group can be performed using protocols for removing a benzyl group such as treatment with a solution of trifluoroacetic acid (TFA) in dichloromethane.

In another embodiment of the method according to the invention PGl is 9- fluorenylmethoxycarbonyl (Fmoc), t-butyl carbamate (Boc), benzyl carbamate (Z), acetamide, trifluoroacetamide, phthalimide, benzyl (Bn), triphenylmethyl (Tr), benzylidene or p- toluenesulfonamide (Ts) and TAG is:

wherein m is > 15 to < 25, p is > 8 to < 18 and q is > 15 to < 25. Preferably, m is 18, 19, 20, 21 or 22, p is 11, 12 or 13 and q is 21, 22 or 23.

In another embodiment of the method according to the invention the depsipeptide according to the general formula (lib) is obtained from precursors according to the general formulas (IVb) and (Illb):

(IVb) (nib) (lib) by: in precursor (IVb), deprotecting the amine group which is protected by the PG2 group in the presence of a base, thereby obtaining a deprotected amine group; in precursor (Illb), deprotecting the carboxylic acid which is protected by the PG3 group in the presence of an acid, thereby obtaining a deprotected carboxylic acid group; condensation of the deprotected amine and carboxylic acid groups, thereby obtaining the depsipeptide (lib); wherein Rl to R12, TAG, PG1, x, and y have a meaning as defined above (in particular, x and y may be 1), PG2 is an amine protecting group and PG3 is a carboxylic acid protecting group. The deprotection and condensation methods may be the same as outlined in connection with the reaction of compounds (II) to (I) above.

Preferably the precursor according to the general formula (IVb) is obtained from precursors according to the general formulas (Vb) and (Vb):

(Vlb) (Vb) (IVb) by: in precursor (Vlb), deprotecting the amine group which is protected by the PG4 group in the presence of a base, thereby obtaining a deprotected amine group; condensation of the deprotected amine group of precursor (Vlb) and carboxylic acid group of precursor (Vb), thereby obtaining the precursor (IVb); wherein R7 to R12, TAG and x have a meaning as defined above (in particular, x may be 1), PG2 has a meaning as defined above and PG4 is an amine protecting group. The deprotection and condensation methods may be the same as outlined in connection with the reaction of compounds (lib) to (I) above.

It is also preferred that the precursor according to the general formula (Illb) is obtained from precursors according to the general formulas (VHIb) and (Vllb):

R1

(Vlllb) (Vllb) (nib) by: in precursor (Vllb), deprotecting the amine group which is protected by the PG5 group in the presence of a base, thereby obtaining a deprotected amine group; - condensation of the deprotected amine group of precursor (Vllb) and carboxylic acid group of precursor (Vlllb), thereby obtaining the precursor (Illb); wherein Rl to R6, PG1 and y have a meaning as defined above (in particular, y may be 1), PG3 has a meaning as defined above and PG5 is an amine protecting group. The deprotection and condensation methods may be the same as outlined in connection with the reaction of compounds (lib) to (I) above.

It is also preferred that the precursor according to the general formula (VIb) is obtained from the esterification of a precursor according to the general formula (IXb) with TAG-OH:

(IXb) (VIb) wherein RIO to R12 and TAG have a meaning as defined above and PG4 has a meaning also as defined above. The protection or tagging of the carboxylic acid group in (IXb) may be effected using a standard condensation system such as DCC/DMAP.

It is also preferred that the precursor according to the general formula (Vllb) is obtained from the esterification of a precursor according to the general formula (X) with PG3-OH:

(Xb) (Vllb) wherein R4 to R6 and y have a meaning as defined above, PG3 also has a meaning as defined above and PG5 also has a meaning as defined above.

It is also preferred that PG3 is TAG as defined above. In another embodiment of the method according to the invention at least one reaction step of the reaction steps resulting in a TAG-bearing molecule is followed by precipitation of crude reaction product in methanol, thereby purifying the crude reaction product.

In another embodiment of the method according to the invention at least one step of the reaction steps in which TAG-protected carboxylic acid groups are deprotected is followed by precipitation of cleaved TAG-OH in methanol and removal of the precipitate by filtration, thereby purifying the crude reaction product.

It is also preferred that precursors (Illb) and (IVb) are identical.

It is also preferred that R3 and R9 are different from each other, Rl and R7 are identical, R2 and R8 are identical, R4 and RIO are identical, R5 and Rl 1 are identical and R6 and R12 are identical. In another embodiment of the method according to the invention the depsipeptide is selected from one of the general formulas (II- 1) to (II- 14b):

(II-l)

-2)

(II-4) A

A

A

1-10) A

(11-11) A

(II-llb) A

wherein in formulas (II- 1 1) to (II- 14) -LINK- is selected from: wherein XI can be C, N, S, O, X2 and X3 can be C or N; O, X2, X3 and X4 can be C or N;

wherein XI , X2, X3 and X4 can be C or N;

and wherein R13 is selected from S0 ₂ NH(CH ₃ ), S0 ₂ NH ₂ , OC(0)CH ₃ , CF ₃ or one the following lactone structures

The present invention furthermore provides a method for the synthesis of cyclic depsipeptides according to the general formula (1) from depsipeptides according to the general formula (lib):

(lie) (I) comprising the steps of

Providing a mixture of compound (lie) and a base in a solvent having an Ei(30)-value of >30 and < 43 - Slow, preferably dropwise addition of a solution of a coupling agent in the solvent to form the cyclic depsipeptide (I) whereby x and y are, independent of each other, 0, 1 or 2 with the proviso that x+y > 1 (preferably, x and y are 1) and Rl , R2, R3, R4, R5, R6, R7, R8, R9, RI O, Rl l and R12 each, independent of each other, represent hydrogen, straight-chain or branched Cl -C8-alkyl, in particular methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, hexyl, isohexyl, sec -hexyl, heptyl, isoheptyl, sec-heptyl, tert-heptyl, octyl, isooctyl, sec-octyl, straight- chain or branched halogenated C1 -C8 alkyl, in particular fluorinated sec-butyl, hydroxy-Cl -C6- alkyl, in particular hydroxymethyl, 1 -hydroxyethyl, Cl -C4-alkanoyloxy-Cl -C6-alkyl, in particular acetoxymethyl, 1 -acetoxyethyl, Cl -C4-alkoxy-Cl -C6-alkyl, in particular methoxymethyl, 1 - methoxyethyl, aryl-Cl -C4-alkyloxy-Cl -C6-alkyl, in particular benzyloxymethyl, 1 - benzyloxyethyl, mercapto-Cl-C6-alkyl, in particular mercaptomethyl, Cl-C4-alkylthio-Cl-C6- alkyl, in particular methylthioethyl, Cl-C4-alkylsulphinyl-Cl-C6-alkyl, in particular methylsulphinylethyl, Cl-C4-alkylsulphonyl-Cl-C6-alkyl, in particular methylsulphonylethyl, carboxy-Cl-C6-alkyl, in particular carboxymethyl, carboxyethyl, Cl-C4-alkoxycarbonyl-Cl-C6- alkyl, in particular methoxycarbonylmethyl, ethoxycarbonylethyl, Cl-C4-arylalkoxycarbonyl-Cl- C6-alkyl, in particular benzyloxycarbonylmethyl, carbamoyl-Cl-C6-alkyl, in particular carbamoylmethyl, carbamoylethyl, amino-Cl-C6-alkyl, in particular aminopropyl, aminobutyl, Cl- C4-alkylamino-Cl-C6-alkyl, in particular methylaminopropyl, methylaminobutyl, C1-C4- dialkylamino-Cl-C6-alkyl, in particular dimethylaminopropyl, dimethylaminobutyl, guanidino-Cl- C6-alkyl, in particular guanidinopropyl, Cl-C4-alkoxycarbonylamino-Cl-C6-alkyl, in particular tert-butoxycarbonylaminopropyl, tert-butoxycarbonylaminobutyl, 9- fluorenylmethoxycarbonyl(Fmoc)amino-Cl-C6-alkyl, in particular 9- fluorenylmethoxycarbonyl(Fmoc)aminopropyl, 9-fluorenylmethoxycarbonyl(Fmoc)aminobutyl, C2-C8-alkenyl, in particular vinyl, allyl, butenyl, C3-C7-cycloalkyl, in particular cyclopentyl, cyclohexyl, cycloheptyl, C3-C7-cycloalkyl-Cl-C4-alkyl, in particular cyclopentylmethyl, cyclohexylmethyl, cycloheptylmethyl, benzyl, substituted benzyl, phenyl, phenyl-Cl-C4-alkyl, in particular phenylmethyl which may optionally be substituted by radicals from the group consisting of halogen, in particular fluorine, chlorine, bromine or iodine.

The term "slow" especially means and/or includes that the solution of coupling agent is added at a rate of < 2 (mol)-% per minute, preferably < 1 (mol)-% per minute more preferred < 0,5 (mol)-% per minute.

In the method according to the invention it has surprisingly been found that cyclic depsipeptides (I), in particular emodepside and closely related structures, can be synthesized in high overall yields. Without being bound to any theory, the inventors believe that this is due to the poor solubility of the cyclic depsipeptide (I) in the solvent in contrast to the open form (lib).

The term "E _T (30)-value" refers to the E _T (30) according Reichardt, Angew. Chem. 1979,119-131, where both a method to determine such values as well as measured values for many standard solvents are listed.

According to one embodiment of the present invention, the Ei(30)-value of the solvent is > 34 and < 39.

The term "solvent" in the sense of the present invention shall also include a mixture of solvents. According to one embodiment of the present invention, the solvent comprises ethyl acetate, according to one embodiment of the present invention, the solvent is ethyl acetate.

Suitable coupling agents which are embodiments of the present invention are given above. According to one embodiment of the present invention, the coupling agent comprises T3P, according to one embodiment of the present invention, the coupling agent is T3P. According to one embodiment, the ratio of coupling agent to compound (lie) prior to the reaction (in mol:mole) is > 1 :1 to < 5:1, preferrably > 2: 1 to < 3: 1.

According to one embodiment, the ratio of base to compound (lib) prior to the reaction (in mol:mole) is > 2:1 to < 10: 1, preferrably > 4: 1 to < 6: 1.

Suitable bases which insofar are embodiments of the present invention comprise NN- diisopropylethylamine (DIEA), Triethylamine, Dimethylaminopyridine (DMAP), Ν- methylmorpholine, pyridine, l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5- diazabicyclo[4.3.0]non-5-ene (DBN)or mixtures thereof. Most preferred is NN- diisopropylethylamine.

According to one embodiment, the temperature during the addition of the coupling agent is < 25°C. In one embodiment of the method according to the invention x is 1, y is 1, Rl, R4, R7 and RIO are methyl, R6 and R12 are methyl, R5 and Rl l are, independent of each other, straight-chain or branched Cl-C4-alkyl or straight-chain or branched halogenated Cl-C4-alkyl and R3 and R9 are, independent of each other, benzyl or substituted benzyl. According to one embodiment of the preferred invention, R3 and/or R9 are p-morpholino substituted benzyl. In one embodiment of the method according to the invention R3 and R9 are identical, Rl and R7 are identical, R2 and R8 are identical, R4 and R10 are identical, R5 and Rl l are identical and R6 and R12 are identical.

According to a preferred embodiment of the present invention, the compound lib is synthesized from compound II or Ila by deprotecting the protective groups A and B or X and Y respectively. Compound lib can be isolated or used in situ to synthesize the depsipeptide (I).

The present invention is also directed towards a linear or cyclic depsipeptide selected from one of the general formulas (II- 1) to (II- 14b) or (1-1) to (1-9) as depicted below or a pharmaceutically or veterinarily acceptable salt thereof:

TAG

(II- 4b)

TAG

(II-9)

(II-llb)

(11-12)

(1-8)

wherein in formulas (II- 11) to (11-14) and (I-l) to (1-9), respectively:

A, B, X and Y are defined as above,

-LINK- is selected from: and R13 is selected from S0 ₂ NH(CH ₃ ), S0 ₂ NH ₂ , OC(0)CH ₃ , CF ₃ or one the following lactone structures:

The terms "veterinarily acceptable salt" and "pharmaceutically acceptable salt" are used throughout the specification to describe any salts of the compounds that are acceptable for administration for pharmaceutical or veterinary applications, and which provides the active compound upon administration.

Veterinarily acceptable salts include those derived from veterinarily acceptable inorganic or organic bases and acids. Suitable salts include those comprising alkali metals such as lithium, sodium or potassium, alkaline earth metals such as calcium, magnesium and barium. Salts comprising transition metals including, but not limited to, manganese, copper, zinc and iron are also suitable. In addition, salts comprising ammonium cations as well as substituted ammonium cations, in which one or more of the hydrogen atoms are replaced by alkyl or aryl groups are encompassed by the invention. Salts derived from inorganic acids including, but not limited to, hydrohalide acids (HQ, HBr, HF, HI), sulfuric acid, nitric acid, phosphoric acid, and the like are particularly suitable. Suitable inorganic salts also include, but not limited to, bicarbonate, and carbonate salts. In some embodiments, examples of veterinarily and agriculturally acceptable salts are organic acid addition salts formed with organic acids including, but not limited to, maleate, dimaleate, fumarate, tosylate, methanesulfonate, acetate, citrate, malonate, tartarate, succinate, benzoate, ascorbate, a- ketoglutarate, and a-glycerophosphate. Of course, other acceptable organic acids may be used.

Alkali metal (for example, sodium, potassium or lithium) or alkaline earth metal (for example calcium) salts of the compounds can also be made by reacting a sufficiently acidic residue on the compounds with a hydroxide of the alkali metal or alkaline earth metal. Veterinarily acceptable salts may be obtained using standard procedures well known in the art, for example by reacting a sufficiently basic compound such as an amine with a suitably acid functional group present in the compound, or by reacting a suitable acid with a suitably basic functional group on the compounds of the invention. Examples

The present invention will be further described with reference to the following examples without wishing to be limited by them.

1. General method The starting building blocks were prepared from commercial available reagents. Unless otherwise noted, reagents and solvents were purchased at highest commercial quality and used without further purification. Methanol and dry toluene, CH2CI2 were purchased from Kanto Chemical Co., Inc. All reactions were monitored by thin-layer chromatography (TLC) using Merck silica gel 60 F254 pre- coated plates (0.25 mm). Flash chromatography was carried out with Kanto Chemical silica gel (Kanto Chemical, silica gel 60N, spherical neutral, 0.040-0.050 mm, Cat. -No. 37563-84). ¾ and ¹³ C NMR spectra were recorded on JEOL JNM-ECA-500 (500 MHz for ¾-NMR and 125 MHz for ¹³ C-NMR). Chemical shifts are expressed in ppm downfield from the internal solvent peaks for CDCI3 (¾ δ = 7.26 ppm, ¹³ C; δ = 77.0 ppm), CD ₃ OD (¾ δ = 3.31 ppm, ¹³ C; δ = 49.0 ppm) and J values are given in Hertz. The following abbreviations were used to explain the multiplicities: s = singlet, d = doublet, t = triplet, q = quartet, dd = double doublet, ddd = double double doublet, dt = double triplet, dq = double quartet, m = multiplet, br = broad. All infrared spectra were measured on a Horiba FT-210 spectrometer. High- and Low-resolution mass spectra were measured on a JEOL JMS-AX505 HA, JEOL JMS-700 MStation and JEOL JMS-T100LP. Optical rotations were measured by using JASCO P-1010 polarimeter. Melting points were measured on a YANACO MP- 500P or OptiMelt (Stanford Research Systems) apparatus.

General method for Fmoc deprotection

Fmoc protected substrate was dissolved into 5% piperidine/CH2Cl2 (generally 0.05 M for substrate) at room temperature and solution was stirred for 3 h. The reaction mixture was subsequently cooled to -5 °C and MeOH was added (five times excess of reaction solution). The resulting heterogeneous solution was stirred for further 30 min at -5 °C, and the colorless precipitate was filtered and washed with additional MeOH to afford corresponding amine as a colorless powder.

General method for the cleavage of TAGa function

Tagged substrates with TAGa dissolved into 50% TFA/CH2C12 (0.05 M for substrate) at room temperature and solution was stirred for generally 1 h. The reaction mixture was subsequently concentrated with toluene (x 3) to remove TFA. To a flask was then added CH2C12 at -5 oC, followed MeOH was added (five times excess of CH2C12). The resulting heterogeneous solution was stirred for further 30 min at -5 oC, and the colorless precipitate was filtered off and washed with additional MeOH. The combined filtrates were concentrated in vacuo. To the resulting product was added 4 M HCl/Dioxane (0.05 M for product) and concentrated with toluene (x 3) to afford corresponding carboxylic acid as a generally brown oil. The crude was used next reaction without further purification. product) and concentrated with toluene (x 3) to afford corresponding carboxylic acid as a generally brown oil. The crude was used next reaction without further purification.

2. Synthesis of Emodepside

In the following the synthesis of emodepside is described, using the compound Benzyl (R)-2- hydroxy-3-(4-morpholinophenyl)propanoate (named EMD-8) which is synthesized from p-fluroro benzaldehyd according to the scheme of Fig. 1. Using this compound, emodepside is synthesized according to the scheme of Fig. 2.

4-Morpholinobenzaldehyde (EMD-22): Into a 100 L reactor, was placed a solution of 4- fluorobenzaldehyde (EMD-21 , 3.6kg, 29.0 mol, 1.0 eq) in 1 -methyl-2-pyrrolidine (36 L, 10.0V), morphline (7.6 kg, 87 mol, 3.0 eq), K2CO3 (10.0 kg, 72.5 mol, 2.5 eq). The resulting mixture was stirred at least for 6 h at 125-130 °C. The reaction was monitored by TLC until no EMD-21. The reaction mixture was diluted with ethyl acetate (18 L, 5 V), H2O (72 L, 20 V), and separated. The water phase was extracted with ethyl acetate (18 L x 2) and combined the organic phase, and washed with H2O (36.0 L x 3). The organic extracts were concentrated under vacuum at below 45 °C until no distillate drops out. The residue was eluted with heptane/ethyl acetate (5: 1 , v/v, 7.2 L) and concentrated under vacuum at below 45 °C. Then, to the above residue was added

heptane/ethyl acetate (5: 1 , v/v, 21.6 L) at 20-25 °C. The solution was stirred at 20-25 °C for 16 h. The mixture was filtered, and the filter cake was washed with heptane (7.3 L). The solids were dried under vacuum at 40-45 °C. This resulted in 4.67 kg (84.8%) of 4-Morpholinobenzaldehyde (EMD-22) as a yellow solid. MS (ES, m/z): 192 (M+H); ¾ NMR (DMSO-de, 300 MHz) 9.74 (s, 1H), 7.74 (d, J= 8.1 Hz, 2H), 7.07(d, J= 8.4 Hz, 2H), 3.75-3.74 (m, 4H), 3.35-3.33 (m,4H).

(Z)-2-methyl-4-(4-morpholinobenzylidene)oxazol-5(4H)-one (EMD-22B): Into a 100 L reactor, was placed a solution of N-acetylglycine (1.22 kg, 10.46 mol, 1.0 eq) in tetrahydrofuran (20 L, 10 V), acetic anhydride (3.2 kg, 31.38 mol, 3.0 eq), zinc(II) chloride (1.48 kg, 10.46 mol, 1.0 eq). The resulting mixture was stirred at 70 °C for 1 h and EMD-22 (2.0 kg, 10.46 mol, 1.0 eq) waa added. Then, the mixture was stirred at 70 °C for another 16 h and monitored by LCMS. After cooling to 20-25 °C, H ₂ 0 (40 L) was added. Then, the mixture was stirred at 0-5 °C for 3 h and filtered. The filter cake was washed with ¾0 (10 L), and dried under vacuum at 40-45 °C. This resulted in 2.29 kg (80.4%) of (Z)-2-methyl-4-(4-morpholinobenzylidene)oxazol-5(4H)-one (EMD-22B) as a brown solid. MS (ES, m/z): 273 (M+H); ^l H NMR (DMSO-de, 300 MHz) 7.84 (s, 1H), 7.47(d, J = 9.0 Hz, 2H), 7.02(d, J= 9.1 Hz, 2H), 3.74-3.71 (m, 4H), 3.32-3.27 (m, 4H).

EMD-22B EMD-23

(ij)-2-hydroxy-3-(4-morpholinophenyl)acrylic acid (EMD-23): Into a 50 L reactor, was placed a solution of EMD-22B (2.2 kg, 8.08 mol, 1.0 eq) in 1,4-dioxane (8.8 L, 4.0 V), HC1 (8.8 L, 4.0 V) at 20-25 °C. The resulting mixture was stirred at 80 °C for 3 h and monitored by LCMS. After cooling to 0-10 °C, the mixture was stirred at 0-10 °C for 16 h and filtered. The fiter cake was dried under vacuum at 40-45 °C, The crude product was eluted with H2O (4.4 L) and stirred at 0-10 °C for 2 h. The mixture was fitered, and the filter cake was dried under vacuum at 40-45 °C. This resulted in 1.17 kg (56.0%) of (£ ^' )-2-hydroxy-3-(4-morpholinophenyl)acrylic acid (EMD-23) as a slater solid. MS (ES, m/z): 250 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.66 (d, J= 8.5 Hz, 2H), 6.97(d, J= 8.6 Hz, 2H), 6.35 (s, 1H), 4.05 (s, 1H, -OH), 3.77-3.74 (m, 4H), 3.19-3.16 (m, 4H).

(R)-2-hydroxy-3-(4-morpholinophenyl)propanoic acid (EMD-24): Into a 2L round-bottom flask purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-23 (66.0 g, 0.26 mol, 1.0 eq) in NN-dimethylformamide (660 mL, 10.0 V), Et ₃ N (107.2g, 1.06 mol, 4.0 eq), RuCl(R,R)-TsDPEN (1.69 g, 0.0026 mol, 0.01 eq) at 20-25 °C. To the above mixture was added formic acid (36.59 g, 0.79 mol, 3.0 eq) dropwise for 2 h at 20-25 °C under N2 atmosphere. Then, the mixture was stirred at 20-25 °C and monitored by LCMS. The reaction was noted for Ml, which was used for next step without further purification.

EMD-8 Benzyl (R)-2-hydroxy-3-(4-morpholinophenyl)propanoate (EMD-8): To a mixture (Ml) was added K2CO3 (109.0 g, 0.78 mol, 3.0 eq) and dropwise benzyl bromide (54.0g, 0.32 mol, 1.2 eq) at 20-25 °C for 1 h. Then, the mixture was stirred at 55-60 °C for another 16 h. The reaction mixture was diluted with ethyl acetate (330 niL, 5 V), H2O (1.2 L, 20 V), and separated. The water phase was extracted with ethyl acetate (330 mL x 2) and combined the organic phase, and washed with H2O (660 mL x 3). The organic extracts were concentrated under vacuum at below 45 °C until no distillate drops out. The residue was eluted with heptane/ethyl acetate (3: 1, v/v, 132 mL) and concentrated under vacuum at below 45 °C. Then, to the above residue was added heptane/ethyl acetate (3: 1, v/v, 264 mL) at 20-25 °C. The mixture was filtered, and the filter cake was washed with heptane (132 mL). The solids were dried under vacuum at 40-45 °C. This resulted in 52 g (58%) of benzyl (R)-2-hydroxy-3-(4-morpholinophenyl)propanoate (EMD-8) as a yellow solid. MS

(ES, m/z): 342 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.40-7.27 (m, 5H), 7.05 (d, J= 8.1 Hz, 2H), 6.82 (d, J= 8.1 Hz, 2H), 5.17 (s, 2H), 4.24 (t, J= 7.5 Hz, 1H), 3.74-3.71 (m, 4H), 3.06-3.03 (m, 4H), 2.90-2.73 (m, 2H).

(R)-l-(benzyloxy)-3-(4-morpholinophenyl)-l-oxopropan-2-yl-A ^r -(tert-butoxycarbonyl)-A ^r - methyl-L-leucinate (EMD-9B): Into a 50 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-8 (1.96 kg, 5.75 mol, 1.0 eq) in

dichloromethane (14.1 L, 10.V), N-(tert-butoxycarbonyl)-N-methyl-L-leucine (1.41 kg, 5.75 mol, 1.0 eq), DMAP (0.77 kg, 6.32 mol, 1.1 eq), EDCI (1.21 kg, 6.32 mol, 1.1 eq) at 20-25 °C. The mixture was stirred at this temperature for at least 3 h and monitored by LCMS. The mixture was concentrated at below 40 °C until no distillate drops out. The residue was dissolved in MTBE (14.1 L) and HC1 (aq, IN, 14.1 L) and filtered. The organic was washed with HC1 (aq, IN, 14.1 L), NaHC03 (sat, 14.1L x 2), and concentrated at below 40 °C until no distillate drops out. Then the residue was resolved in heptane/MTBE (28.2 L, 8: 1, v/v), and concentrated at below 40 °C until no distillate drops out. To the above residue was added heptane/MTBE (15.5 L, 8: 1, v/v) at 20-25 °C and seed crystal (0.2%>, w/w), and kept stirring for overnight at 20-25 °C. The mixture was filtered; the filter cake was washed with heptane (7.0 L). The solids were dried under vacuum at 40-45 °C. This resulted in 2.56 kg (78.3%) of(R)-l -(benzyloxy)-3-(4-morpholinophenyl)-l-oxopropan-2-yl- N-(tertbutoxycarbonyl)-N-methyl-L-leucinate (EMD-9B) as a light yellow solid. MS (ES, m/z): 569 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.38-7.26 (m, 5H), 7.10 (d, J= 8.2 Hz, 2H), 6.96 (d, J = 8.1 Hz, 2H), 5.25-5.22 (m, 1H), 5.12-5.10 (m, 2H), 4.07-3.99 (m, 1 H), 3.79-3.76 (m„ 4H), 3.19- 2.97 (m, 6H), 2.57 (s, 3H), 1.42-1.34 (m, 11H), 1.24-1.15 (m, 1H), 0.88-0.82 (m, 6H).

EM D-9B EM D-10B

(R)-2-((A ^r -(tert-butoxycarbonyl)-A ^r -methyl-L-leucyl)oxy)-3-(4-morpholinophenyl)propanoic acid (EMD-10B): Into a 50 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-9B (400g, 0.7 mol, 1.0 eq) in EtOH (4.0 L, 10.0V) at 20-25 °C, The reactor was evacuated and flushed with nitrogen for three times and Pd/C (28.0 g, 7% w/w) was added. Then the reactor was evacuated and flushed with nitrogen for three times again, and kept hydrogen bubbling underneath the reaction mixture surface. The mixture was stirring for at least for 4 h at 20-25 °C and monitored by HPLC. After the reaction completing, the hydrogen bubbling was cut off. The mixture was filtered through celite (2.0 kg) and filter cake was rinsed with EA (0.8 L), and the filtrate was concentrated at below 40 °C until no distillate drops out. This resulted in 317.7 g (94.4%) of (R)-2-((N-(tert-butoxycarbonyl)-N-methyl-L-leucyl)oxy)-3-(4- morpho- linophenyl)propanoic acid (EMD-10B) as a dark yellow oil; MS (ES, m/z): 479 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.10 (d, J = 8.4 Hz, 2H), 6.85 (d, J= 8.7 Hz, 2H), 5.03-5.02 (m, 1H), 4.81 - 4.53 (m, 1H), 3.73 (t, J = 7.2 Hz, 4H), 3.05 (t, J = 7.2 Hz, 4H), 2.96-2.90 (m, 1H), 2.63 (s, 3H), 1.42-1.16 (m, 12 H), 0.89-0.84 (m, 6H).

Boc-L-MeLeu-OH H-L-Lac-OBn

EMD-12B

(R)-l-(benzyloxy)-l-oxopropan-2-yl methyl-L-leucinate (EMD-12B): Into a 10 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of N-(tert- butoxycarbonyl)-N-methyl-L-leucine (240.3 g, 0.98 mol, 1.0 eq) in THF (3.9 L, 16 v), benzyl (S)- 2-hydroxypropanoate (176.5 g, 0.98 mol, 1.0 eq), triphenylphosphine (385.1 g, 1.47 mol, 1.5 eq) at 20-25 °C. After cooling to below 10 °C, diisopropyl azodiformate (297 g, 1.47 mol, 1.5 eq) was added dropwise with stirring at below 10 °C. Then, warming up to 20-25 °C and stirring for at least 2 h. The reaction was monitored by HPLC until benzyl (S)-2-hydroxypropanoate less than or equal to 0.5%. The resulting mixture was diluted with ethyl acetate (3.9 L) and washed with NaHC03 (sat, 3.9 L x 2), brine (3.9 L x 2). The organic phase was concentrated at below 40 °C until no distillate drops out. The residue was exchanged with tert-Butyl methyl ether (240 mL x 2), concentrated below 40 °C until no distillate drops out, and slurryed with tert-butyl methyl ether (960 mL) for at least 3 h. The mixture was filtered and the filter cake was washed with tert-butyl methyl ether (240 mL). The filtrate was concentrated at below 40 °C until no distillate drops out. This resulted in crude product of (R)-l-(benzyloxy)-l-oxopropan-2-yl N-(tert-butoxycarbonyl)-N- methyl-L-leucinate (EMD-IB) as a yellow oil, which was used for next step without further purification. Into a 10 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-IB in HC1/EA (1.2 L, 5.0 eq) below 25 °C. The mixture was stirred for at least 1 h at 20-25 °C and monitored by HPLC until EMD-IB less than or equal to 0.5%. The solution was concentrated at below 40 °C until no distillate drops out. The residue was exchanged with tert- Butyl methyl ether (240 mL x 2), concentrated below 40 °C until no distillate drops out, and resolved with tert-butyl methyl ether (1.92 L). Then, the seed crystal (0.1%, w/w) was added and stirred for at least 5 h at 20-25 °C. The mixture was filtered and the filter cake was washed with tert-butyl methyl ether (0.24 L). The solid was dried under vacuum at 40 + 5 °C and 270 g of crude product was obtained as a white solid. The solid was dissolved in ethyl acetate (810 mL) by warming up to 40 + 5 °C and tert-butyl methyl ether (4.05 L) was added. Subsequently, cooling down to 20-25 °C and the seed crystal (0.1%. w/w) was added. The mixture was stirred for at least 5 h at 20-25 °C, filtered, the filter cake was washed with tert-butyl methyl ether (0.24 L). The solid was dried under vacuum at 40 + 5 °C. This resulted in 226.7 g (67.3%, two steps) of (R)-l- (benzyloxy)-l-oxopropan-2-yl methyl-L-leucinate (EMD-12B) as a white solid. MS (ES, m/z): 308 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.41-7.35 (m, 5 H), 5.28 (q, J= 7.1 Hz, 1H), 5.20 (s, 2H), 2.51 (s, 3H), 1.77-1.71 (m, 3H), 1.50-1.48 (m, 3H), 0.90-0.87 (m, 6H).

(R)-l-(benzyloxy)-l-oxopropan-2-yl N-((R)-2-((N-(tert-butoxycarbonyl)-N-methyl-L-leuc yl)oxy)-3-(4-morpholinophenyl)propanoyl)-N-methyl-L-leucinat e (EMD-13B): Into a 10 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-10B (275.0 g, 0.57 mol, 1.0 eq) in ethyl acetate (2.2 L, 8.0 V), EMD-12B ( 197.7 g, 0.57 mol, 1.0 eq), NN-diisopropylethylamine (372.2 g, 2.88 mol, 5.0 eq) at 20-25 °C. After cooling to 10 -20 oC, propylphosphonic anhydride (916.4 g, 1.44 mol, 2.5 eq) was added dropwise with stiring at below 25 °C. Then, the mixture was stirred at 20-25 °C for at least 2.5 h and monitored by HPLC until EMD-12B less than or equal to 1.0%. The solution was diluted with heptane (2.75 L) at 0—10 °C and quenched slowly with HC1 (aq, 1.0Ν, 2.75 L). The organic phase was washed HC1 (aq, 1.0Ν, 2.75 L), NaHCOs (sat, 2.75 L x 2), and concentrated at below 40 °C until no distillate drops out. This resulted in 429.8 g (97.4%) of (R)-l-(benzyloxy)-l-oxopropan-2-yl N- ((R)-2-((N-(tert-butoxycarbonyl)-N-methyl-L-leucyl)oxy)-3-(4 -morpholinophenyl)propanoyl)-N- methyl-L-leucinate (EMD-13B) as a yellow thick oil. MS (ES, m/z): 768 (M+H);

EM D-14B

(R)-l-(benzyloxy)-l-oxopropan-2-yl-N-methyl-N-((R)-2-((me thyl-L-leucyl)oxy)-3-(4-morphol- inophenyl)propanoyl)-L-leucinate (EMD-14B): Into a 5 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-13B (245 g, 0.32 mol, 1.0 eq) in HC1/EA (735, 3.0 V) below 25 °C. The mixture was stirred for at least 1 h at 20 -25 °C and monitored by HPLC until EMD-13B was less than or equal to 0.5%. The resulting solution was concentrated at below 40 °C until no distillate drops out and exchanged with ethyl acetate (245 mL x 2) at below 40 °C. The residue was dissolved in ethyl acetate (735 mL) and NN- diisopropylethylamine (245 g) was added at 20 -25 °C. The mixture was washed with NaHC03 (sat, 735 mL x 2). The organic was concentrated at below 40 °C until no distillate drops out. This resulted in 186.9 g (89.9%) of (R)-l-(benzyloxy)-l-oxopropan-2-yl-N-methyl-N-((R)-2-((methy l- L-leucyl)oxy)-3-(4-morphol-inophenyl)propanoyl)-L-leucinate (EMD-14B) as a yellow oil. MS (ES, m/z): 668 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.41-7.32 (m, 5 H), 7.17 (d, J= 8.5 Hz, 2H), 6.86 (d, J= 8.6 Hz, 2H), 5.50-5.47 (m, 1H), 5.20-5.04 (m, 4H), 4.23-3.99 (m, 1H), 3.74-3.72 (m, 4H), 3.09-2.76 (m, 10H), 2.22-1.99 (m, 3H), 1.63-1.35 (m, 5H), 1.29-1.16 (m, 4H), 0.97-0.70 (m, 12H).

E D-13B EMD-15B

(6S,9R,12S,15R)-6,12-diisobutyl-2,2,5,ll,15-pentamethyl-9 -(4-morpholinobenzyl)-4,7,10,13- tetraoxo-3,8,14-trioxa-5,ll-diazahexadecan-16-oic acid (EMD-15B): Into a 10 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-13B (274.2g, 0.36 mol, 1.0 eq) in EtOH (2.8 L, 10.0V) at 20-25 °C, The reactor was evacuated and flushed with nitrogen for three times and Pd/C (19.2 g, 7% w/w) was added. Then the reactor was evacuated and flushed with nitrogen for three times again, and kept hydrogen bubbling underneath the reaction mixture surface. The mixture was stirring for at least for 4 h at 20-25 °C and monitored by HPLC. After the reaction completing, the hydrogen bubbling was cut off. The mixture was filtered through celite (2.0 kg) and filter cake was rinsed with ethyl acetate (0.56 L), and the filtrate was concentrated at below 40 °C until no distillate drops out. This resulted in 237.4 g (98.0%) of(6S,9R, 12S, 15R)-6, 12-diisobutyl-2,2,5, 11,15-pentamethyl-9-(4-morpholinobenzyl)-4,7, 10,13- tetraoxo-3,8,14-trioxa-5,l l-diazahexadecan-16-oic acid (EMD-15B) as a yellow oil; MS (ES, m/z): 678 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.15 (d, J= 8.4 Hz, 2H), 6.85 (d, J= 8.3 Hz, 2H), 5.52-5.40 (m, 1H), 5.09-5.02 (m, 1H), 4.91-4.53 (m, 2 H), 3.74-3.72 (m, 4H), 3.15-3.04 (m, 5H), 2.94-2.86 (m, 4H), 2.65-2.64 (m, 3H), 1.43-1.28 (m, 16H), 0.93-0.77 (m, 12H).

EM D-15B EMD-14B

EMD-16B

(R)-l-(benzyloxy)-l-oxopropan-2-yl N-methyl-N-((6S,9R,12S,15R,18S,21R)-6,12,18-triiso butyl-2,2,5,ll,15,17-hexamethyl-9,21-bis(4-morpholinobenzyl) -4,7,10,13,16,19-hexaoxo -3,8,14,20-tetraoxa-5,ll,17-triazadocosan-22-oyl)-L-leucinat e (EMD-16B): Into a 10 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-15B (147.6 g, 0.22 mol, 1.0 eq) in ethyl acetate (2.2 L, 8.0 V), EMD-14B (145.5 g, 0.22 mol, 1.0 eq), NN-diisopropylethylamine (139.6 g, 1.08 mol, 5.0 eq) at 20-25 °C. After cooling to 10 -20 °C, propylphosphonic anhydride (346.4 g, 0.54 mol, 2.5 eq) was added dropwise with stiring at below 25 °C. Then, the mixture was stirred at 20-25 °C for at least 2.5 h and monitored by HPLC until EMD-12B less than or equal to 0.5 %>. The solution was diluted with heptane (2.2 L) at 0-10 °C and quenched slowly with HCl (aq, 1.0 N, 2.2 L). The organic phase was washed HCl (aq, 1.0N, 2.2 L), NaHCC (sat, 2.2 L x 2), concentrated at below 40 °C until no distillate drops out, and exchanged with heptane/MTBE (0.44 L, 1.5: 1, v/v) at below 40 °C.The residue was dissolved in heptane/MTBE (1.65 L, 1.5:1, v/v) and seed crystal (0.1%, w/w) was added at 20-25 °C. The mixture was stirred for at least 16h at 20-25 °C and filtered. The filter cake was washed with heptane (0.66 L), dried under vacuum at 40-45 .This resulted in 242.4 g (83.4%) of (R)-l- (benzyloxy)-l-oxopropan-2-yl N-methyl-N-((6S,9R,12S,15R,18S,21R)-6,12,18-triiso-butyl- 2,2,5,11,15,17-hexamethyl-9,21 -bis(4-morpholinobenzyl)-4,7, 10,13,16,19-hexaoxo-3 , 8, 14,20- tetraoxa-5,l l,17-triazadocosan-22-oyl)-L-leucinate (EMD-16B) as a white solid: MS (ES, m/z): 1328 (M+H);

EMD-20B

(R)-l-(benzyloxy)-l-oxopropan-2-yl N-((2R,5S,8R,llS,14R,17S)-5,ll-diisobutyl-6,8,12,19 -tetramethyl-17-(methylamino)-2,14-bis(4-morpholinobenzyl)-4 ,7,10,13,16-pentaoxo-3,9,15- trioxa-6,12-diazaicosanoyl)-N-methyl-L-leucinate (EMD-20B): Into a 5 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-16B (376.4 g, 0.28 mol, 1.0 eq) in HC1/EA (1128 mL, 3.0 V) below 25 °C. The mixture was stirred for at least 1 h at

20-25 °C and monitored by HPLC until EMD-16B was less than or equal to 0.5%. The resulting solution was concentrated at below 40 °C until no distillate drops out and exchanged with ethyl acetate (376.4 mL x 2) at below 40 °C. The residue was dissolved in ethyl acetate (1128 mL) and NN-diisopropylethylamine (376.4 g) was added at 20-25 °C. The mixture was washed with NaHC03 (sat, 1128 mL x 2). The organic was concentrated at below 40 °C until no distillate drops out. This resulted in 313.56 g (90.1%) of (R)-l-(benzyloxy)-l-oxopropan-2-yl N- ((2R,5 S, 8R, 11 S, 14R, 17S)-5, 11 -diisobutyl-6, 8, 12,19-tetramethyl- 17-(methylamino)-2, 14-bis(4- morpholinobenzyl)-4,7, 10,13,16-pentaoxo-3,9, 15-trioxa-6, 12-diazaicosanoyl)-N-methyl-L- leucinate (EMD-20B) as a yellow oil; MS (ES, m/z): 1228 (M+H);

EMD-18B

(3S,6R,9S,12R,15S,18R,21S,24R)-3,9,15,21-tetraisobutyl-8, 12,14,20,24-pentamethyl-6,18- bis(4-morpholinobenzyl)-4,7,10,13,16,19,22-heptaoxo-5,ll,17, 23-tetraoxa-2,8,14,20- tetraazapentacosan-25-oic acid (EMD-18B): Into a 10 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-20B (313.56 g, 0.26 mol, 1.0 eq) in EtOH (3.2 L, 10.0V) at 20-25 °C, The reactor was evacuated and flushed with nitrogen for three times and Pd/C (21.95 g, 7% w/w) was added. Then the reactor was evacuated and flushed with nitrogen for three times again, and kept hydrogen bubbling underneath the reaction mixture surface. The mixture was stirring for at least for 4 h at 20-25 °C and monitored by HPLC until EMD-20B was less than or equal to 1.0%. After the reaction completing, the hydrogen bubbling was cut off. The mixture was filtered through celite (2.0 kg) and filter cake was rinsed with ethyl acetate (0.64 L x 3), and the filtrate was concentrated at below 40 °C until no distillate drops out. The residue was slurred with ethyl acetate (0.7 L) for at least 3h and filtered; the filter cake was rinsed with ethyl acetate (0.32L x 2). The solid was dried under vacuum at 40-45 °C. This resulted in 234.2 g (80.6%) of (3S,6R,9S,12R, 15S, 18R,21 S,24R)-3,9,15,21 -tetraisobutyl-8, 12,14,20,24- pentamethyl-6, 18-bis(4-morpholinobenzyl)-4,7, 10, 13,16, 19,22-heptaoxo-5, 11 , 17,23-tetraoxa- 2,8,14,20-tetraazapentacosan-25-oic acid (EMD-18B) as an off white solid; MS (ES, m/z): 1138 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.34-7.16 (m, 8H), 5.68-5.28 (m, 3H), 5.11 -5.04 (m, 3H), 4.93-4.86 (m, 1H), 4.03-3.99 (m, 1H), 3.85-3.82 (m, 8H), 3.23-3.22 (m, 8H), 3.23-2.76 (m, 13H), 2.49 (s, 2H), 2.07 (s, 2H), 1.66-1.45 (m, 8H), 1.43-1.16 (m, 10H), 0.99-0.64 (m, 24H).

Emodepside

(3S,6R,9S,12R,15S,18R,21S,24R)-3,9,15,21-tetraisobutyl-4, 6,10,16,18,22-hexamethyl-12,24- bis(4-morpholinobenzyl)-l,7,13,19-tetraoxa-4,10,16,22-tetraa zacyclotetracosan- 2,5,8,11,14,17,20,23-octaone (Emodepside): Into a 10 L reactor purged and maintained with an inert atmosphere of nitrogen, was placed a solution of EMD-18B (234.2 g, 0.21 mol, 1.0 eq) in ethyl acetate (3.8 L, 16.0 V), NN-diisopropylethylamine (131.84 g, 1.02 mol, 5.0 eq) at 20-25 °C. After cooling to 10 -20 °C, propylphosphonic anhydride (324.5 g, 0.51 mol, 2.5 eq) was added dropwise with stiring at below 25 °C. Then, the mixture was stirred at 20-25 °C for at least 2.5 h and monitored by HPLC until EMD-18B less than or equal to 0.5 %. The mixture was diluted with heptane (2.38L) at 0-10 °C and quenched slowly with HC1 (aq, 1.0 N, 2.38 L). The organic phase was washed HC1 (aq, 1.0N, 2.38 L), NaHCOs (sat, 2.38 L x 2), concentrated at below 40 °C until no distillate drops out, and exchanged with EtOH (0.48 L x 2) at below 40 °C.The residue was dissolved in EtOH (0.72 L) at 45-55 °C and seed crystal (0.1%, w/w) was added at 20-25 °C. The mixture was stirred for at least 16h at 20-25 °C and filtered. The filter cake was rinse with EtOH (0.24L). The solid was dried under vacuum at 40 + 5 °C. The crude product was recrystallized with ethyl acetate. This resulted in 118.24 g (51.3%) of (3S,6R,9S,12R,15S,18R,21 S,24R)-3,9,15,21- tetraisobutyl-4,6, 10,16,18,22-hexamethyl- 12,24-bis(4-morpholinobenzyl)- 1 ,7,13,19-tetraoxa- 4,10,16,22-tetraazacyclotetracosan 2,5,8,11,14,17,20,23 -octaone (Emodepside) as a white solid; MS (ES, m/z): 1120 (M+H); ¾ NMR (DMSO-de, 300 MHz) 7.16 (d, J= 8.7 Hz, 4H), 6.87 (d, J= 8.2 Hz, 4H), 5.68 (q, J= 8.0 Hz, 1H), 5.51-4.04 (m, 7H), 3.74-3.71 (m, 8H), 3.08-3.04 (m, 8H), 2.99-2.96 (m, 4H), 2.90-2.88 (m, 4H), 2.83-2.82 (m, 4H), 2.78 (s, 2H), 2.70 (s, 2H), 1.78-1.38 (m, 8H), 1.31-1.14 (m, 6H), 0.97-0.69 (m, 28H).

3. Preparation of PF1022A (Method 1 ; cf. reaction scheme in FIG. 3 and NMR spectra in FIG. 4) 3-1. Synthetic procedure -Fmoc-jY-MeLeu-D-Lac-O-TAGa

C1

C ₁

HO-TAGa

To a stirred solution of HO-TAGa (1.69 g, 1.85 mmol) in CH2CI2 (37 mL) was added 0.2 M toluene solution of unit 1 (12.0 mL, 2.40 mmol), 4-dimethylaminopyridine (12 mg, 93.0 μιηοΐ), and NiV-dicyclohexylcarbodiimide (1.30 g, 2.78 mmol) at room temperature under N2 atmosphere. After stirring for 2 h, the reaction mixture was then cooled to -5 °C, and MeOH (185 mL) was added. The resulting heterogeneous solution was stirred for further 15 min at -5 °C, and the colorless precipitate was filtered and washed with additional MeOH (500 mL) to afford A'-Fmoc- A-MeLeu-D-Lac-O-TAGa (2.46 g, 100%) as a colorless powder. mp: 44 - 45 °C

[a] _D ²⁴ : -10.2 (c 1.0, CHCI3)

¾-NMR (500 MHz, CDCI3) δ : 7.78-7.74 (complex m, 2H), 7.60-7.56 (complex m, 2H), 7.39 (m, 2H), 7.29 (m, 2H), 6.50 (s, 4/3H), 6.48 (s, 2/3H), 5.12-5.00 (complex-m, 4H), 4.67 (dd, J= 6.3, 9.7 Hz, 3/10H), 4.58 (dd, J = 6.3 Hz, 10.9 Hz, 4/10H), 4.50 (dd, J = 6.9 Hz, 10.3 Hz, 6/10H), 4.38- 4.34 (complex m, 9/10H), 4.30 (m, 5/10H), 4.23 (t, J = 6.3 Hz, 3/10H), 3.93 (m, 6H), 2.86 (s, 2H), 2.83 (s 1H), 1.76 (m, 6H), 1.64-1.42 (complex m, 9H), 1.31-1.14 (complex m, 87H), 0.96-0.87 (complex m, 14H), 0.78 (d, J= 6.9 Hz, 1H). HRMS (FAB, NBA matrix) m/z : 1334.0748 (M ⁺ , calcd for C86H143NO9 : 1334.0763)

^-MeLeu-D-Lac-O-TAGa (1)

1 Following the procedure described for general procedure of Fmoc deprotection, A-Fmoc-A- MeLeu-D-Lac-O-TAGa (1.00 g, 0.749 mmol) was converted to 1 (816 mg, 98%) as a colorless powder.

¾-NMR (500 MHz, CDCI3) δ : 6.50 (s, 2H), 5.16 (q, J = 6.9 Hz, 1H), 5.08 (d, J = 12.0 Hz, 1H), 5.04 (d, J = 12.0 Hz, 1H), 3.93 (m, 6H), 3.30 (t, J = 7.5 Hz, 1H), 2.37 (s, 3H), 1.75 (m, 6H), 1.53- 1.42 (complex m, 10H), 1.32-1.25 (complex m, 86H), 0.93-0.86 (complex m, 15H).

¹³ C-NMR (125 MHz, CDCI3) δ : 170.6, 153.3, 138.4, 130.2, 106.4, 73.5, 69.2, 68.9, 67.6, 61.4, 42.2, 34.5, 32.0, 30.4, 29.8 (x2), 29.5 (x2), 26.2, 25.0, 22.8, 22.6, 22.5, 17.1, 14.2.

HRMS (FAB, NBA matrix) m/z : 1113.0151 [(M+H) ⁺ , calcd for C71H134NO7 : 1113.0160]

A-Fmoc-A-MeLeu-D-PhLac-A-MeLeu-D-LacO-TAGa (2)

2 To a stirred solution of 1 (800 mg, 0.719 mmol) in CH ₂ C1 ₂ (25 mL) was added unit 2 (426 mg, 0.827 mmol), NN-diisopropylethylamine (0.429 mL, 2.52 mmol), and PyBroP (496 mg, 1.222 mmol) at room temperature. After stirring for 88 h, the reaction mixture was crystallized by the procedure described in synthesis of A^Fmoc-A^MeLeu-D-Lac-O-TAGa to afford 2 (1.11 g, 96%) as a colorless powder.

'H-NMR (500 MHz, CDCls) δ : 7.76-7.72 (complex m, 2H), 7.62-7.40 (complex m, 2H), 7.39- 7.17 (complex m, 9H), 6.47 (m, 2H), 5.47-5.27 (complex m, 2H), 5.15-4.97 (complex m, 4H), 4.69-4.13 (complex m, 3H), 3.92 (complex m, 6H), 3.07 (m, 2H), 2.85 (complex, 6H), 1.80-1.25 (complex m, 105H), 1.02-0.72 (complex m, 21H). HRMS (FAB, NBA matrix) m/z : 1632.2163 [(M+Na) ⁺ , calcd for Cio ₂ Hi6 ₄ N ₂ Oi ₂ Na: 1632.2182] -MeLeu-D-PhLac- -MeLeu-D-Lac-OH (3)

Following the procedure described for general procedure of TAGa cleavage, 2 (614 mg, 0.381 mmol) was converted to 3 (261 mg, 95%) as an yellow oil, which was used next reaction without further purification.

A ^r -MeLeu-D-PhLac-A ^r -MeLeu-D-Lac-0-TAGa (4)

4

2

Following the procedure described for general procedure of Fmoc deprotection, 2 (472 mg, 0.293 mmol) was converted to 4 (404 mg, 100%) as a colorless powder.

'H-NMR (500 MHz, CDCI3) δ : 7.27 (m, 5H), 6.49 (s, 2H), 5.50 (dd, J= 5.7, 8.6 Hz, 1H), 5.32 (dd, J = 4.6, 10.9 Hz, 1H), 5.09-5.00 (complex m, 3H), 3.93 (m, 6H), 3.28 (t, J = 6.9 Hz, 1H), 3.09 (m, 2H), 2.92 (s, 3H), 2.27 (s, 3H), 1.82-1.25 (complex m, 105H), 0.89-0.77 (complex m, 21H).

¹³ C-NMR (125 MHz, CDCI3) δ : 175.6, 175.1, 175.0, 174.8, 170.9, 170.5 (x2), 170.4, 169.8, 169.7, 166.7, 165.1, 153.3, 138.5, 138.3, 135.8 (x2), 130.2, 129.5, 129.3, 128.7, 128.6, 128.5 (x2), 127.2, 107.0, 106.9, 105.4, 78.1, 73.5, 71.9, 71.6, 69.4, 69.2, 68.9, 67.7, 67.5, 66.9, 65.6, 61.3, 61.2, 59.7, 57.7, 54.7, 42.3, 42.2, 42.1, 40.0, 38.8, 37.5, 36.9, 34.4, 34.3, 32.8, 32.0, 31.3, 30.4, 29.8 (x2), 29.6, 29.5 (x2), 26.2, 25.0, 24.8, 24.7, 24.6, 23.4, 22.9, 22.8, 22.5 (x2), 22.4 (x2), 21.9, 21.4, 20.5, 17.0, 16.9, 16.8, 14.2.

HRMS (FAB, NBA matrix) m/z : 1388.1664 [(M+H) ⁺ , calcd for C87H155N2O10 : 1388.1682]

A^Fmoc-^-MeLeu-D-PhLac-^-MeLeu-D-Lac-^-MeLeu-D-PhLac-^-Me Leu-D-Lac-O-TAGa (5)

To a stirred solution of 2 (330 mg, 0.238 mmol) in CH ₂ C1 ₂ (4.8 mL) was added 3 (221 mg, 0.309 mmol), NN-diisopropylethylamine (0.150 mL, 0.881 mmol), and PyBroP (197 mg, 0.428 mmol) at room temperature. After stirring for 42 h, the reaction mixture was crystallized by the procedure described in synthesis of N-Fmoc-N-MeLeu-D-Lac-O-TAGa to afford 5 (477 mg, 96%) as a colorless powder.

'H-NMR (500 MHz, CDCls) δ : 7.74 (m, 2H), 7.53 (m, 2H), 7.38 (m, 2H), 7.32-7.15 (complex m, 12H), 6.48 (m, 2H), 5.51-4.96 (complex m, 10H), 4.70-4.12 (complex m, 3H), 3.93 (m, 6H), 3.23 (dd, J = 6.9, 13.7 Hz, 1H), 3.08-2.70 (complex m, 15H), 1.80-1.25 (complex m, 114H), 0.95-0.78 (complex m, 33H).

HRMS (FAB, NBA matrix) m/z : 2106.4949 [(M+Na) ⁺ , calcd for Ci28H ₂ 02N ₄ Oi8Nai : 2106.4912] A^MeLeu-D-PhLac-^-MeLeu-D-Lac-^-MeLeu-D-PhLac-^-MeLeu-D-Lac- O-TAGa

Following the procedure described for general procedure of Fmoc deprotection, 5 (450 mg, 0.206 mmol) was converted to the corresponding amine (398 mg, 98%) as a colorless powder. 'H-NMR (500 MHz, CDC1 ₃ ) δ : 7.25 (m, 10H), 6.48 (s, 2H), 5.57-4.99 (complex m, 9H), 3.93 (m, 6H), 3.26-2.78 (complex m, 14H), 2.24 (s, 3H), 1.80-1.25 (complex m, 114H), 0.90-0.78 (complex m, 33H).

¹³ C-NMR (125 MHz, CDCI3) δ : 175.6, 175.2 (x2), 171.5, 171.1, 170.8 (x2), 170.6, 170.5 (x2), 170.3, 153.3, 138.5 (x2), 138.3, 136.1, 135.9, 135.5, 130.2, 130.1, 130.0, 129.8, 129.7, 129.6, 129.4 (x2), 128.8, 128.7, 128.6, 128.5, 127.4 (x2), 127.2, 127.1, 126.9, 126.8, 107.0 (x2), 106.9, 73.5, 72.5, 72.2, 71.7, 71.6, 69.8, 69.4, 69.2, 68.1, 68.0, 67.8, 67.5 (x2), 66.9, 61.4, 57.4, 55.2, 54.8, 54.6 (x2), 38.8, 37.7, 37.6, 37.4 (x2), 37.1 (x2), 37.0, 36.9, 34.7, 34.6, 32.2, 32.0, 31.9, 31.7, 31.6, 31.4, 31.3, 31.2, 30.4, 29.8 (x2), 29.6, 29.5 (x2), 26.2, 24.9, 24.8 (x2), 24.7, 24.6, 24.5, 23.5, 23.4, 23.3, 23.1 (x2), 23.0, 22.8, 22.7, 22.5, 22.4, 22.3, 22.0, 21.5, 21.4, 21.3 (x2), 20.5, 16.9, 16.8, 16.6, 14.2. HRMS (FAB, NBA matrix) m/z : 1862.4425 [(M+H) ⁺ , calcd for C113H193N4O16 : 1862.4412] A^MeLeu-D-PhLac-^-MeLeu-D-Lac-^-MeLeu-D-PhLac-^-MeLeu-D-Lac- OH

Following the procedure described for general procedure of TAGa cleavage, A-MeLeu-D-PhLac- A-MeLeu-D-Lac-A-MeLeu-D-PhLac-A-MeLeu-D-LacO-TAGa (380 mg, 0.204 mmol) was converted to the corresponding carboxylic acid (198 mg, 98%) as a yellow oil, which was used next reaction without further purification.

PF1022A

Reaction for 0.005M concentration of substrate

A crude of previous reaction (90 mg, 0.0895 mmol) was dissolved in CH2CI2 (18 mL, 0.005 M). The reaction mixture was added NN-diisopropylethylamine (76 μ∑, 4.48 mmol) and PyBOP (93 mg, 0.179 mmol) at room temperature. After being stirred for 48 h, the reaction mixture was quenched with saturated aqueous NaHC03 (18 mL) at 0 °C and this mixture was extracted with CHCI3 (20 mL x 2). The combined organic layers were washed with 10% aqueous NaHS04 (60 mL) and brine (60 mL), dried over Na2SO i, filtered and concentrated in vacuo. The crude was purified by column chromatography on silica gel (CHCI3 : MeOH = 400 : 1 to 40 : 1) to provide PF1022A (55 mg, 65%) as a colorless solid.

Reaction for 0.05M concentration of substrate

According to the procedure for cyclization mentioned above, a crude of previous reaction (90 mg, 0.0895 mmol) was cyclized in CH2CI2 (1.8 ml, 0.05 M) with NN-diisopropylethylamine (76 uL, 4.48 mmol) and PyBOP (93 mg, 0.179 mmol) at room temperature for 48 h to provide PF1022A (40 mg, 49%) as a colorless solid. mp: 100-103 °C

[a] ²² _D : -99.4 °C (c 0.06, MeOH)

IR (KBr) v: 1743, 1666, 1466, 1412, 1265, 1188, 1126, 1080, 1026, 748, 701 ¾-NMR (500 MHz, CD ₃ OD) δ : 7.29 (m, 10H), 5.82 (t, J = 7.5 Hz, 1H), 5.72 (m, 2H, rotamer), 5.54 (q, J = 6.9 Hz, 1H), 5.44 (dd, J = 4.6, 11.7 Hz, 1H), 5.40 (dd, J = 4.6, 11.7 Hz, 1H, rotamer), 5.23 (dd, J = 4.6, 11.7 Hz, 1H), 5.18 (q, J = 6.9 Hz, 1H, rotamer), 4.77 (dd, J = 3.4, 11.2 Hz, 1H), 3.14 (m, 4H), 3.00 (s, 5/2H, rotamer), 2.91 (m, 7H, rotamer), 2.82 (s, 5/2H, rotamer), 1.84 (m, 1H), 1.77-1.47 (complex m, 11H), 1.39 (d, J = 6.3 Hz, 3H), 1.05 (d, J = 6.3 Hz, 3H), 0.98 (d, J = 6.9 Hz, 3H), 0.80 (d, J= 6.3 Hz, 3H), 0.95-0.82 (complex m, 18H).

¹³ C-NMR (125 MHz, CD3OD) δ : 174.4, 173.5, 173.1, 173.1, 172.3, 172.0, 171.0, 170.7, 136.4, 136.2, 130.8, 130.7, 130.7, 129.8, 129.7, 129.7, 128.4, 128.3, 72.5, 72.3, 69.9, 68.5, 58.6, 55.7, 55.5, 55.4, 39.0, 38.9, 38.6, 38.6, 37.8, 37.3, 32.0, 31.3, 31.1, 30.0, 26.2, 26.1, 25.5, 25.2, 23.9, 23.7, 23.7, 23.6, 21.7, 21.6, 21.4, 21.1, 17.5, 17.2. HRMS (FAB, NBA matrix) m/z : 971.5353 [(M+Na) ⁺ , calcd for C ₅ 2H ₇ 6N ₄ Oi2Nai : 971.5357]

*Literature (J Antibiot, 1992, 45, 692-697) mp: 104-106 °C

[a] ²² _D : -102 °C (c 0.1, MeOH)

¾-NMR (400 MHz, CD3OD) δ : 7.30 - 7.20 (PhH, 10H), 5.80 and 5.75 (C _a H-PhLac, 1Ηχ2), 5.54 and 5.16 (C _a H-Lac, 1Ηχ2), 5.43, 5.42, 5.22 and 4.78 (C _a H-Leu, 1Ηχ4), 3.22-3.15 (C _P H ₂ -PhLac, 2Hx2), 3.00, 2.90, 2.88 and 2.80 (N-Me-Leu, 3Hx4), 1.87-1.50 (C _P H ₂ -Leu, 2Hx4), 1.40 (C _Y H-Leu, 1HX4), 1.38 (C _P H ₃ -Lac, 3H), 1.02-0.75 (C ₈ H ₃ -Leu, 6Hx4), 0.88 (C _P H ₃ -Lac, 3H).

¹³ C-NMR (100 MHz, CD3OD) δ : 174.4, 173.4, 172.4, 172.4, 172.1, 172.1, 171.0, 170.8, 136.5, 136.2, 130.7, 130.7, 130.7, 130.7, 129.7, 129.7, 129.7, 129.7, 128.3, 128.2, 72.5, 72.3, 69.9, 68.4, 58.6, 55.7, 55.5, 55.4, 39.0, 38.9, 38.6, 38.6, 37.9, 37.4, 32.0, 31.3, 31.1, 29.9, 26.2, 26.1, 25.6, 25.2, 23.6, 23.6, 23.5, 23.5, 21.7, 21.6, 21.4, 21.0, 17.5, 17.2.

4. Preparation of PF1022A (Method 2; cf. reaction scheme in FIG. 5) 4-1. Synthetic procedure -Fmoc-jY-MeLeu-D-PhLac-O-TAGa

To a stirred solution of HO-TAGa (170 mg, 0.186 mmol) in CH ₂ C1 ₂ (3.7 mL) was added 0.1 M toluene solution of unit 2 (2.42 mL, 0.242 mmol), 4-dimethylaminopyridine (1.1 mg, 9.30 μηιοΐ), and NiV-dicyclohexylcarbodiimide (58 mg, 0.279 mmol) at room temperature under N2 atmosphere. After stirring for 1 h, the reaction mixture was crystallized by the procedure described in synthesis of N-Fmoc-N-MeLeu-D-Lac-O-TAGa to afford N-Fmoc-N-MeLeu-D-PhLac-O- TAGa (266 mg, 100%) as a colorless powder. mp _: 44 _ 45 °c

[a] _D ²⁷ : -6.1 (c 1.74, CHCI3)

'H-NMR (500 MHz, CDCI3) δ : 7.76 (complex m, 2H), 7.54 (m, 2H), 7.39 (m, 2H), 7.30 (m, 1H), 7.26-7.14 (complex m, 4H), 7.08 (m, 2H) 6.44 (m, 2H), 5.20 (m, 1H), 5.04-4.94 (complex m, 3H), 4.61-4.15 (complex m, 3H), 3.92 (m, 6H), 3.10 (m, 2H), 2.72 (s, 3H), 1.76 (m, 6H), 1.60-1.25 (complex m, 93H), 0.90-0.71 (complex m, 15H).

¹³ C-NMR (125 MHz, CDCI3) δ : 177.2, 175.2, 169.5, 153.3, 138.4, 135.9, 130.0, 129.6, 129.3, 128.6, 128.4, 127.1, 107.5, 107.2, 73.5, 73.1, 69.2, 67.8, 61.6, 42.5, 37.4, 34.5, 32.0, 30.4, 29.8 (x2), 29.6, 29.5, 26.2, 24.8, 22.8, 22.6, 22.5, 14.2. HRMS (FAB, NBA matrix) m/z : 1410.1063 [(M+H) ⁺ , calcd for C92H147NO9 : 1410.1076] TV-MeLeu-D-PhLac-O-TAGa (6)

6 Following the procedure described for general procedure of Fmoc deprotection, A^Fmoc-A^ MeLeu-D-PhLac-O-TAGa (457 mg, 0.324 mmol) was converted to 6 (378 mg, 99%) as a colorless powder. mp _: 48 - 49 °C

[a] _D ²⁶ : +4.2 (cl .10, CHCI3) 'H-NMR (500 MHz, CDCI3) δ : 7.22 (m, 5H), 6.48 (s, 2H), 5.28 (dd, J= 4.0, 10.3 Hz, 1H), 5.08 (d, J = 12.0 Hz, 1H), 5.04 (d, J= 12.0 Hz, 1H), 3.93 (m, 6H), 3.24 (dd, J = 4.0 Hz, 14.3 Hz, 1H), 3.17 (t, J= 6.9 Hz, 1H), 3.07 (dd, J = 9.7, 14.3 Hz, 1H), 2.18 (s, 3H), 1.76 (m, 6H), 1.48-1.25 (complex m, 93H), 0.90-0.76 (complex m, 15H).

HRMS (FAB, NBA matrix) m/z : 1189.0458 [(M+H) ⁺ , calcd for C77H138NO7 : 1189.0473] A^-Fmoc-^-MeLeu-D-Lac-^-MeLeu-D-PhLacO-TAGa (7)

To a stirred solution of 6 (358 mg, 0.301 mmol) in CH2CI2 (6.0 ml) was added 0.1 M toluene solution of unit 1 (3.31 mL, 0.331 mmol), N.N-diisopropylethylamine (0.15 mL, 0.903 mmol), and PyBroP (211 mg, 0.452 mm) at room temperature. After stirring for 13 h, reaction mixture was crystallized by the procedure described in synthesis of A^Fmoc-A^MeLeu-D-Lac-O-TAGa to afford 7 (468 mg, 97%) as a colorless powder. mp _: 47 _ 48 °C

[a] _D ²⁶ : -13.9 (c 1.10, CHCI3)

'H-NMR (500 MHz, CDCI3) δ : 7.75 (m, 2H), 7.59 (m, 2H), 7.39 (m, 2H), 7.30-7.09 (complex m, 7H), 6.44 (m, 2H), 5.36-4.96 (complex m, 6H), 4.71^1.24 (complex m, 3H), 3.93 (t, J = 6.5 Hz, 6H), 3.14 (m, 2H), 2.90-2.81 (complex s, 6H), 1.80-1.25 (complex m, 105H), 0.96-0.76 (complex m, 21H).

¹³ C-NMR (125 MHz, CDCI3) δ : 171.6, 171.2, 171.1, 170.9, 169.3, 157.0, 153.3, 144.3, 143.9, 141.4 (x2), 138.4, 135.9, 130.0, 129.9, 129.8, 129.7, 129.6, 129.5, 129.3, 128.7, 128.5, 128.4, 127.7, 127.6, 127.0, 125.3, 125.1, 125.0, 124.9, 120.0, 107.5, 107.2, 74.1, 74.0, 73.9, 73.8, 73.5, 71.3, 69.2, 67.9, 67.7, 57.4, 57.2, 56.7, 56.6 (x2), 54.5 (x2), 47.4 (x2), 47.3, 37.6, 37.3, 37.2, 37.1, 37.0, 32.0, 31.1, 30.7, 30.6 (x2), 30.5, 30.4, 30.3, 30.2, 29.8 (x2), 29.6, 29.5 (x2), 26.2, 24.9, 24.8, 24.7, 24.6, 24.4, 23.4, 23.2, 22.9, 22.8, 22.1, 21.4, 21.2, 16.8, 14.2.

HRMS (FAB, NBA matrix) m/z : 1609.2274 (M ⁺ , calcd for C102H168N2O12 : 1609.2284) -MeLeu-D-Lac- -MeLeu-D-PhLacOH (8)

Following the procedure described for general procedure of TAGa cleavage, 7 (244 mg, 0.152 mmol) was converted to 8 (106 mg, 97%) as a yellow oil, which was used next reaction without further purification.

-MeLeu-D-Lac- -MeLeu-D-PhLacO-TAGa (9)

Following the procedure described for general procedure of Fmoc deprotection, 7 (204 mg, 0.127 mmol) was converted to 9 (176 mg, 100%) as a colorless powder. mp _: 47 _ 48 °C [a] _D ²⁶ : -2.1 (c l .l, CHCl ₃ ) 'H-NMR (500 MHz, CDC1 ₃ ) δ : 7.19 (m, 5H), 6.45 (s, 2H), 5.45 (q, J= 6.9 Hz, 1H), 5.31 (ddd, J = 4.6, 11.2, 19.6 Hz, 1H), 5.22 (dd, J = 5.2, 6.9 Hz, 1H), 5.03 (m, 2H), 3.94 (m, 6H), 3.33-2.95 (complex m, 3H), 2.80 (s, 3H), 2.38 (s, 3H), 1.82-1.25 (complex m, 105H), 0.96-0.75 (complex m, 21H). ¹³ C-NMR (125 MHz, CDC1 ₃ ) δ : 175.0, 171.1, 171.0, 169.2, 153.3, 130.0, 129.8, 129.7, 129.3, 128.7, 128.6, 128.5, 127.4, 127.1, 126.9, 107.5, 107.2, 73.8, 73.5, 71.3, 69.2, 67.9, 67.7, 67.4, 67.3, 61.2, 57.5, 54.6, 42.3, 42.2, 37.3, 37.2, 37.0, 34.6, 32.0, 31.1, 30.4, 29.8 (x2), 29.6, 29.5 (x2), 26.2, 25.0, 24.8, 23.4, 23.0, 22.8, 22.7, 22.4, 22.1, 21.3, 16.9, 16.8, 14.2. HRMS (FAB, NBA matrix) m/z: 1388.1676 [(M+H) ⁺ , calcd for C87H155N2O10: 1388.1682]

A^Fmoc-^-MeLeu-D-Lac-^-MeLeu-D-PhLac-^-MeLeu-D-Lac-^-MeLe u-D-PhLac-O-TAGa (10)

To a stirred solution of 9 (155 mg, 96.2 μτηοΐ) in CH ₂ C1 ₂ (1.9 mL) was added 8 (103 mg, 0.144 mmol), NN-diisopropylethylamine (73 μ∑, 0.434 mmol), and PyBroP (112 mg, 0.241 mmol) at room temperature. After stirring for 66 h, the reaction mixture was crystallized by the procedure described in synthesis of -Fmoc- -MeLeu-D-Lac-O-TAGa to afford 10 (201 mg, 100%) as a colorless powder. mp _: 47 _ 48 °C

[a] _D ²⁷ : -27.2 (c 1.1, CHC1 ₃ )

'H-NMR (500 MHz, CDCI3) δ : 7.75 (m, 2H), 7.59 (m, 2H), 7.38 (m, 2H), 7.30-7.12 (complex m, 12H), 6.44 (m, 2H), 5.43-4.96 (complex m, 10H), 4.69-4.22 (complex m, 3H), 3.93 (m, 6H), 3.24- 2.69 (complex m, 16H), 1.80-1.25 (complex m, 114H), 0.95-0.75 (complex m, 33H).

¹³ C-NMR (125 MHz, CDCI3) δ : 174.1, 171.5, 171.4, 171.3, 171.2, 171.1 (x2), 170.9, 170.8, 170.7, 170.6, 170.5, 170.4, 170.0, 169.2, 157.0, 156.5, 153.3, 144.3, 144.2, 144.0 (x2), 141.4 (x2), 138.6, 138.4, 136.1, 136.0, 135.9 (x2), 135.7, 135.6, 135.3, 130.0, 129.8, 129.7, 129.6, 129.5, 129.3, 128.8, 128.7, 128.6, 128.4, 127.7, 127.4, 127.1 (x2), 127.0. 125.3, 125.2, 125.1, 125.0, 120.0,

107.5, 107.2, 107.1, 73.9, 73.5, 72.5, 71.3, 69.2, 68.0, 67.7, 57.5, 56.6 (x2), 55.1, 55.0, 54.9, 54.7, 54.4, 47.4, 47.3, 40.9, 40.6, 38.7, 37.6, 37.3, 37.2, 37.1, 32.0, 31.9, 31.7, 31.5, 31.3, 31.2, 31.0, 30.7, 30.6, 30.4, 30.3, 29.8 (x2), 29.6, 29.5 (x2), 25.0, 24.9, 24.8, 24.7, 24.5, 24.4 (x2), 23.4, 23.3, 23.1, 23.0, 22.9, 22.8, 22.3, 22.1, 22.0, 21.3, 21.2, 16.8, 16.6, 16.5, 14.2.

HRMS (FAB, NBA matrix) m/z : 2106.4910 [(M+Na) ⁺ , calcd for Ci ₂ 8H ₂ 02N ₄ Oi8Na: 2106.4912] A^MeLeu-D-Lac-^-MeLeu-D-PhLac-^-MeLeu-D-Lac-^-MeLeu-D-PhLac- O-TAGa

Following the procedure described for general procedure of Fmoc deprotection, 10 (181 mg, 86.8 μιηοΐ) was converted to the corresponding amine (163 mg, 100%) as a colorless powder. mp _: 47 _ 48 °C

[a] _D ²⁷ : -18.7 (c 1.3, CHCI3)

'H-NMR (500 MHz, CDCI3) δ : 7.20 (m, 10H), 6.44 (s, 2H), 5.50-4.95 (complex m, 9H), 3.93 (m, 6H), 3.31-2.72 (complex m, 14H), 2.36 (m, 3H), 1.80-1.25 (complex m, 114H), 0.99-0.81 (complex m, 33H).

¹³ C-NMR (125 MHz, CDC1 ₃ ) δ : 171.4, 171.2, 171.0, 170.9, 170.6, 170.4, 153.3, 138.3, 136.1, 136.0, 135.9, 135.8, 130.0, 129.8 (x2), 129.7, 129.6 (x3), 129.5, 129.4, 129.2, 129.2 (x2), 128.8, 128.7, 128.6, 128.4, 127.4, 127.3, 127.2 (x2), 127.1, 127.0, 107.5, 107.2, 107.1, 73.9, 73.5, 72.3, 72.2, 71.3, 69.2, 68.0 (x2), 67.7, 67.4, 61.3, 55.2, 55.0, 54.8, 54.5, 54.4, 42.4, 40.6, 38.7, 37.7, 37.2, 37.1, 34.7 (x2), 32.0, 31.7, 31.5, 31.0, 30.4, 29.8 (x2), 29.6, 29.5 (x2), 26.2, 25.0, 24.9 (x2), 24.7, 23.5, 23.4 (x2), 23.3, 23.2, 23.0, 22.8, 22.4, 22.1, 21.9, 21.3 (x2), 16.9, 16.8 (x3), 16.7, 16.6, 16.5, 14.2.

HRMS (FAB, NBA matrix) m/z : 1862.4462 [(M+H) ⁺ , calcd for C113H193N4O16: 1862.4412] A^MeLeu-D-Lac-^-MeLeu-D-PhLac-^-MeLeu-D-Lac-^-MeLeu-D-PhLac- OH

Following the procedure described for general procedure of TAGa cleavage, A^MeLeu-D-Lac-A^ MeLeu-D-PhLac-^-MeLeu-D-Lac-^-MeLeu-D-PhLac-O-TAGa (143 mg, 0.768 mmol) was converted to the corresponding carboxylic acid (78 mg, 100%) as a yellow oil, which was used next reaction without further purification. PF1022A

A crude of previous reaction (78 mg, 0.0777 mmol) was dissolved in CH2CI2 (16 mL, 0.005 M). The reaction mixture was added NN-diisopropylethylamine (66 μ∑, 0.389 mmol) and PyBOP (81 mg, 0.155 mmol) at room temperature. After stirring for 48 h, the reaction mixture was quenched with saturated aqueous NaHCC (16 mL) at 0 °C and this mixture was extracted with CHCI3 (20 mL x 2). The combined organic layers were washed with 10% aqueous NaHS04 (60 mL) and brine (60 mL), dried over Na2S04, filtered and concentrated in vacuo. The crude was purified by column chromatography on silica gel (CHCI3 : MeOH = 400 : 1 to 40 : 1) to provide PF1022A (48mg, 65%) as a colorless solid.

All physical data for synthetic PF 1022 A matched with the data of authentic PF1022A. 5. Preparation of Emodepside (Method 1 ; cf. reaction schemes in FIG. 6, NMR spectra in FIG. 7 and LC-UV spectra in FIG. 8)

5-1. Synthetic procedure

A^Fmoc-A^MeLeu-D-morphPhLac-A^MeLeu-D-Lac-O-TAGa (11)

11

To a stirred solution of 1 (259 mg, 0.233 mmol) in CH ₂ C1 ₂ (4.7 mL) was added 0.2 M toluene solution of unit 3 (0.122 mL, 0.244 mmol), NN-diisopropylethylamine (0.12 mL, 0.698 mmol), and PyBroP (163 mg, 0.349 mmol) at room temperature. After being stirred at 40 h, reaction mixture was crystallized by the procedure described in synthesis of A'-Fmoc-A'-MeLeu-D-Lac-O- TAGa to afford 11 (395 mg, 100%) as a colorless powder.

¾-NMR (500 MHz, CDC1 ₃ ) δ : 7.74 (m, 2H), 7.57 (m, 2H), 7.42-7.27 (complex m, 4H), 7.05 (m, 2H), 6.70 (d, J = 8.6 Hz, 2H), 6.48 (s, 2H), 5.40 (dd, J = 6.9, 8.4 Hz, 3/1 OH, rotamer), 5.35-5.27 (complex m, 17/1 OH), 5.10^1.97 (complex m, 4H), 4.72-4.12 (complex m, 3H), 3.93 (m, 6H), 3.75 (m, 4H), 3.00-2.79 (complex m, 12H), 1.80-1.60 (complex m, 9H), 1.49-1.42 (complex m, 9H), 1.27 (complex m, 87H), 0.93-0.80 (complex m, 21H).

HRMS (FAB, NBA matrix) m/z: 1717.2701 [(M+Na) ⁺ , calcd for CioeHmNsOisNa: 1717.2710]

Following the procedure described for general procedure of TAGa cleavage, 11 (210 mg, 0.124 mmol) was converted to 12 (100 mg, -0.124 mmol) as a brown oil. This crude was used next reaction without further purification.

A-MeLeu-D-morphPhLac-A-MeLeu-D-Lac-O-TAGa (13)

Following the procedure described for general procedure of Fmoc deprotection, 11 (158 mg, 0.0934 mmol) was converted to 13 (138 mg, 100%) as a colorless powder.

¾-NMR (500 MHz, CDCls) δ : 7.15 (m, 2H), 6.83 (d, J = 8.6 Hz, 2H), 6.49 (s, 2H), 5.47 (dd, J = 6.9, 8.0 Hz, 1H), 5.32 (dd, J = 4.9, 11.2 Hz, 1H), 5.09-5.00 (complex m, 3H), 3.94 (m, 6H), 3.85 (m, 4H), 3.27 (t, J= 6.9 Hz, 1H), 3.13-2.79 (complex m, 9H), 2.29 (s, 3H), 1.81-1.25 (complex m, 105H), 1.01-0.78 (complex m, 21H).

HRMS (FAB, NBA matrix) m/z: 1473.2214 [(M+H) ⁺ , calcd for C91H162N3O11 : 1473.2209]

A^Fmoc-A^MeLeu-D-morphPhLac-A^MeLeu-D-Lac-A^MeLeu-D-morph PhLac-A^MeLeu-D- Lac-O-TAGa (14)

To a stirred solution of 13 (138 mg, 0.934 mmol) in CH2CI2 (1.9 niL) was added 12 (100 mg, -0.124 mmol), NN-diisopropylethylamine (48 μΐ, 0.280 mmol), and PyBroP (65 mg, 0.140 mmol) at room temperature. After stirring for 18 h, the reaction mixture was crystallized by the procedure described in synthesis of -Fmoc- -MeLeu-D-Lac-O-TAGa to afford 14 (211 mg, 100%) as a colorless powder. 'H-NMR (500 MHz, CDC1 ₃ ) δ : 7.75 (m, 2H), 7.58 (m, 2H), 7.42-7.28 (complex m, 4H), 7.09 (m, 4H), 6.77 (m, 4H), 6.48 (s, 2H), 5.45-5.15 (complex m, 6H), 5.06-4.97 (complex m, 4H), 4.73- 4.12 (complex m, 3H), 3.95-3.73 (complex m, 14H), 3.15-2.73 (complex m, 24H), 1.80-1.25 (complex m, 114H), 0.96-0.77 (complex m, 33H).

HRMS (FAB, NBA matrix) m/z: 2276.5962 [(M+Na) ⁺ , calcd for CoeftieNeChoNa : 2276.5967]

A^MeLeu-D-morphPhLac-A^MeLeu-D-Lac-A^MeLeu-D-morphPhLac-^ -MeLeu-D-Lac-O- TAGa

Following the procedure described for general procedure of Fmoc deprotection, 14 (211 mg, 0.0934 mmol) was converted to the corresponding amine (178 mg, 94%) as a colorless powder. 'H-NMR (500 MHz, CDCls) δ : 7.15 (m, 4H), 6.82 (m, 4H), 6.49 (s, 2H), 5.14 (t, J= 7.45 Hz, 1H), 5.44-5.09 (complex m, 5H), 5.07-5.00 (complex m, 3H), 3.93 (m, 6H), 3.85 (m, 8H), 3.32 (m, 1H), 3.17-2.74 (complex m, 21H), 2.33 (s, 3H), 1.81-1.64 (complex m, 12H), 1.55-1.25 (complex m, 102H), 1.03-0.77 (complex m, 33H). HR-MS (FAB, NBA matrix+Nal) m/z: 2032.5488 [(M+H) ⁺ , calcd for Ci2iH ₂ 07N ₆ Oi8 : 2032.5467]

A^MeLeu-D-morphPhLac-A^MeLeu-D-Lac-A^MeLeu-D-morphPhLac-^ -MeLeu-D-Lac-OH

Following the procedure described for general procedure of TAGa cleavage, A^MeLeu-D- morphPhLac-A'-MeLeu-D-Lac-A'-MeLeu-D-morphPhLac-A'-MeLeu-D-L acO-TAGa (178 mg, 0.0876 mmol) was converted to the corresponding carboxylic acid (-0.0876 mmol) as a crude oil, which was used next reaction without further purification.

Emodepside (highly diluted condition using PyBOP)

Emodepside

(8 steps for longest linear from HO-TAGa) 42% overall yield from HO-TAGa To a crude of carboxylic acid (-0.0876 mmol) in CH ₂ C1 ₂ (18 mL, 0.005 M) was added NN- diisopropylethylamine (0.10 mL, 0.613 mmol) and PyBOP (91 mg, 0.175 mmol) at room temperature. After stirring for 19 h, the reaction mixture was quenched with saturated aqueous NaHC03 (18 mL) at 0 °C and this mixture was extracted with CHCb (20 mL x 3). The combined organic layers were washed with 10% aqueous NaHSC>4 (60 mL) and brine (60 mL), dried over Na2S04, filtered and concentrated in vacuo. The crude was purified by column chromatography on silica gel (CHCI3 : MeOH = 400 : 1 to 100 : 1) to provide Emodepside (45 mg, 46% for 2 steps) as a light yellow solid. mp: 98-103 °C [a] _D ²⁴ : -40.3 (c 0.67, CHCI3)

IR (neat) v _max : 2954, 2862, 1743, 1659, 1520, 1458, 1412, 1265, 1234, 1188, 1119, 1072, 1026, 926, 810.

¾-NMR (500 MHz, CDCI3) δ : 7.14-7.11 (complex m, 4H), 6.83-6.79 (complex m), 5.64-5.54 (complex m), 5.52-5.43, 5.43-5.39, 5.33, 5.18, 5.06 and 4.46 (5 m, 6H), 3.85 (apparently t, 8H), 3.15-3.04 (complex m, 8H), 3.04-2.92 (complex m, 4H), 3.00, 2.82, 2.79, 2.72 and 2.71 (5 s, 12H), 1.82-1.24 (complex m, 18H), 1.03-0.79 (complex m, 30H).

¹³ C-NMR (125 MHz, CDCI3) δ : 171.6, 171.2, 171.0, 170.9, 170.3, 170.2, 170.1, 169.8, 169.7, 150.2, 130.4, 130.2, 115.7, 115.6, 71.2, 70.8, 68.5, 66.8, 66.7, 57.1, 54.0, 53.9, 49.3, 49.2, 38.0, 37.5, 37.1, 36.9, 36.8, 36.7, 36.6, 36.1, 31.1, 30.6, 30.4, 29.7, 29.6, 29.3, 25.0, 24.8, 24.6, 24.5, 24.5, 24.1, 23.6, 23.5, 23.4, 23.3, 23.3, 23.1, 22.6, 21.6, 21.5, 21.1, 21.1, 21.0, 20.8, 17.1, 15.7.

HRMS (ESI) m/z: 1141.6404 [(M+Na) ⁺ , calcd for CeoHooNeOwNa: 1141.6413]

*Literature (Eur. J. Org. Chem., 2012, 1546-1553)

¾-NMR (400 MHz, CDCI3) δ : 7.17-7.09 (m, 4 H, Ar-H), 6.86-6.77 (m, 4 H, Ar-H), 5.67-5.54 (m, 2 H, CaH-Lac), 5.53-5.38, 5.34, 5.19, 5.08 and 4.47 (5 m, 6 H, CaH-Leu, CaH-morphPhLac), 3.88-3.81 (pseudo-t, 8 H, OCH ₂ morpholine), 3.15-3.08 (m, 8 H, N-CH ₂ -morpholine), 3.07-2.85 (m, 4 H, C H ₂ -morphPhLac), 3.00, 2.83, 2.80, 2.74 and 2.73 (5 s, 12 H, NCH ₃ ), 1.83-1.20 (m, 18 H, C H ₂ -Leu, CyH-Leu, CH ₃ -Lac), 1.05-0.77 (m, 30 H, C8H ₃ -Leu, C H ₃ -Lac).

¹³ C-NMR (100 MHz, CDCI3) δ : 171.7, 171.2, 171.0, 170.6, 170.4, 170.2, 169.8, 141.7, 130.6, 130.4, 116.9, 116.1, 71.3, 70.8, 68.6, 66.9, 66.6, 66.5, 57.1, 54.0, 49.9, 38.1, 37.5, 37.2, 36.7, 36.2, 31.2, 30.5, 29.4, 24.9, 24.7, 24.2, 23.6, 23.5, 23.5, 23.4, 21.2, 21.1, 20.9, 17.1, 15.8.

Emodepside (slow addition condition using T3P)

% or steps

Emodepeide

(8 steps for longest linear from HO-TAGa 85% overall yitld from HO-TAGa

Cleavage of TAGa: To a stirring solution of linear compound on TAG (179.0 mg, 0.088 mmol) in DCM (1.8 mL) was added TFA (1.8 mL) at room temperature. After stirring for 6 h at room temperature, the solution was concentrated in vacuo. The resulting mixture was dissolved into toluene (10 mL) and concentrated under reducing pressure for 3 times to remove excess TFA. The crude residue was dissolved into CH2CI2 (1.0 mL), then recrystalhzed for the cleaved TAGa materials by the addition of MeOH (8.0 mL) at room temperature. The precipitates were filtered off through Celite ^® pad and washed with MeOH (20 mL). The combined filtrates were concentrated in vacuo. To the resulting product was added 4 M HCl/Dioxane (0.05 M for product), followed by diluted with toluene (10 mL) and concentrated to afford the TFA salt free product. To remove excess HC1 from a crude product, the product was dissolved again into toluene (10 mL) and concentrated under reducing pressure for 2 times.

Cyclization: To a stirring solution of T3P ^® (50% in EtOAc, 110 uL, 0.187 mmol) in DIPEA (110\L, 0.187 mmol) was added dropwise a crude linear compound (0.088 mmol) in DCM (1.8 mL, 0.05 M including wash) over 2.5 h at room temperature. After stirring for 20 h at room temperature, the reaction mixture was quenched with sat. NaHC03 aq. (3.0 mL), extracted with CHCI3 (2.0 mL x 3). The combined organic layers were dried over sodium sulfate, filtered, and concentrated in vacuo. The crude residue was purified by silica gel column chromatography on silica gel (CHCk/MeOH = 100/1) to provide Emodepside (86.4 mg, 88%) as an amorphous. The analytical data was identified by the authentic sample.

6. Preparation of Emodepside (Method 2; cf. reaction scheme in FIG. 9) A-Fmoc-A-MeLeu-D-morphPhLac-O-TAGa

To a stirred solution of HO-TAGa (381 mg, 0.417 mmol) in CH ₂ C1 ₂ (8.4 mL) was added 0.2 M toluene solution of unit 3 (2.71 mL, 0.542 mmol), 4-dimethylaminopyridine (2.5 mg, 20.8 μιηοΐ), and NiV-dicyclohexylcarbodiimide (129 mg, 0.626 mmol) at room temperature under N2 atmosphere. After stirring for 1 h, the reaction mixture was crystallized by the procedure described in synthesis of A-Fmoc-A-MeLeu-D-Lac-O-TAGa to afford A-Fmoc-A-MeLeu-D- morphPhLac- O-TAGa (628 mg, 100%) as a colorless powder. mp : 46-47 °C

[a] _D ²⁷ = -3.1 (c l .0, CHCI3) 'H-NMR (500 MHz, CDCI3) δ : 7.78 (d, J = 7.5 Hz, 1H), 7.74 (d, J = 7.5 Hz, 1H), 7.57 (m, 2H), 7.39 (m, 2H), 7.27 (m, 2H), 6.98 (d, J = 8.6 Hz, 1H), 6.96 (d, J = 8.6 Hz, 1H), 6.67 (m, 2H), 6.49 (2 s, rotamer 4:3, 2H), 5.17 (2 dd, rotamer, J = 4.0 Hz, 8.0 Hz, 1H), 5.08-4.98 (complex m, 3H), 4.67-4.13 (complex m, 3H), 3.93 (m, 6H), 3.73 (m, 4H), 3.08 (dd, J = 4.0 Hz, 14.6 Hz, 1H), 3,07- 2.95 (complex m, 5H), 2.80 (rotamer 4:3, 3H), 1.76 (m, 6H), 1.64-1.53 (complex m, 3H), 1.45 (m, 6H), 1.28 (complex m, 84H), 0.93-0.86 (complex m, 14H), 0.76 (d, J = 6.3 Hz, 1H).

HRMS (FAB, NBA matrix) m/z: 1495.1583 (M ⁺ , calcd for C96H154N2O10 : 1495.1604) -MeLeu-D-morphPhLac-O-TAGa (15)

15 Following the procedure described for general procedure of Fmoc deprotection, -Fmoc-A ⁷ - MeLeu-D-morphPhLac-O-TAGa (628 mg, 0.417 mmol) was converted to 15 (530 mg, 100%) as a colorless powder. mp : 49-50 °C

[a] _D - +5.7 (c l .0, CHCI3) ¾-NMR (500 MHz, CDCI3) δ : 7.08 (d, J = 8.6 Hz, 2H), 6.80 (d, J = 8.6 Hz, 2H), 6.51 (s, 2H), 5.24 (dd, J = 4.0, 9.7 Hz, 1H), 5.07 (q, J = 12.0 Hz, 2H), 3.94 (m, 6H), 3.85 (m, 4H), 3.18 (m, 2H), 3.10 (m, 4H), 3.00 (d, J = 10.3, 14.3 Hz, 1H), 2.21 (s, 3H), 1.76 (m, 6H), 1.47 (m, 6H), 1.34-1.25 (complex m, 87H), 0.88 (t, J= 6.9 Hz, 9H), 0.80 (d, J= 6.9 Hz, 3H), 0.79 (d, J= 6.9 Hz, 3H).

HRMS (FAB, NBA matrix) m/z : 1274.0986 [(M+H) ⁺ , calcd for C81H145N2O8 : 1274. 1001] A^Fmoc-^-MeLeu-D-Lac-^-MeLeu-D-morphPhLac-O-TAGa (16)

To a stirred solution of 15 (530 mg, 0.417 mmol) in CH ₂ C1 ₂ (8.4 mL) was added 0.2 M toluene solution of unit 1 (0.22 mL, 0.44 mmol), NN-diisopropylethylamine (0.212 mL, 1.25 mmol), and PyBroP (291 mg, 0.62 mmol) at room temperature. After stirring for 16 h, the reaction mixture was crystallized by the procedure described in synthesis of A^Fmoc-A^MeLeu-D-Lac-O-TAGa to afford 16 (670 mg, 95%) as a colorless powder. mp ; 48-49 °C

[a] _D ²⁷ = -12.4 (c l .0, CHCls)

'H-NMR (500 MHz, CDCI3) δ : 7.76 (m, 2H), 7.61 (m, 2H), 7.38 (m, 2H), 7.30 (m, 2H), 7.02 (m, 2H), 6.74 (m, 2H), 6.49 (2 s, rotamer, 2H), 5.38-5.22 (complex m, 2H), 5.15-4.98 (complex m, 4H), 4.47 (complex m, 3H), 3.94 (m, 6H), 3.81 (m, 4H), 3.12-2.78 (complex m, 12H), 1.82-1.56 (complex m, 9H), 1.53-1.40 (complex m, 8H), 1.34-1.26 (complex m, 88H), 0.98-0.75 (complex m, 21H).

HRMS (FAB, NBA matrix) m/z: 1694.2828 (M ⁺ , calcd for C106H171N3O13 : 1694.2812) -Fmoc- -MeLeu-D-Lac- -MeLeu-D-morphPhLac-OH (17)

Following the procedure described for general procedure of TAGa cleavage, 16 (376 mg, 0.222 mmol) was converted to 17. In the case of this substrate, the reaction required longer time than that of the general condition of TAGa cleavage (ca. 1 h). The reaction of 16 in 50% TFA/CH2CI2 at room temperature was needed to stir for 8 h to consume all of starting material, and gave product 17 (178 mg, 0.222 mmol) as a crude oil, which was used next reaction without further purification. -MeLeu-D-Lac- -MeLeu-D-morphPhLac-O-TAGa (18)

Following the procedure described for general procedure of Fmoc deprotection, 16 (290 mg, 0.171 mmol) was converted to 18 (251 mg, 100%) as a colorless powder. mp : 43-45 °C [α]ϋ ²⁵ = -2.8 (c 1.0, CHCI3)

'H-NMR (500 MHz, CDCI3) δ : 7.07 (d, J = 8.6 Hz, 2H), 6.79 (d, J = 8.6 Hz, 2H), 6.49 (s, 2H), 5.46 (q, J = 6.9 Hz, 1H), 5.33 (dd, J = 5.2, 10.9 Hz, 1H), 5.17 (dd, J = 5.2, 7.5 Hz, 1H), 5.06 (m, 2H), 3.95 (m, 6H), 3.84 (m, 4H), 3.33 (t, J = 7.5 Hz, 1H), 3.11-3.06 (complex m, 6H), 2.82 (2 s, rotamer 4: 1, 3H), 2.40 (s, rotamer, 3H), 1.82-1.59 (complex m, 10H), 1.52-1.43 (complex m, 8H), 1.34-1.25 (complex m, 87H), 0.97-0.86 (complex m, 21H).

HRMS (FAB, NBA matrix + NaI) m/z: 1473.2222 [(M+H) ⁺ , calcd for C9 ₁ H ₁ 6 ₂ N3O ₁₁ : 1473.2209]

A^Fmoc-A^MeLeu-D-Lac-A^MeLeu-D-morphPhLac-A^MeLeu-D-Lac-A ^MeLeu-D- morphPhLac-O-TAGa (19)

To a stirred solution of 18 (251 mg, 0.171 mmol) in CH ₂ C1 ₂ (3.4 mL) was added 17 (178 mg, 0.222 mmol), NN-diisopropylethylamine (87 μ∑, 0.513 mmol), and PyBroP (120 mg, 0.257 mmol) at room temperature. After stirring at 46 h, the reaction mixture was crystallized by the procedure described in synthesis of A'-Fmoc-A'-MeLeu-D-Lac-O-TAGa to afford 19 (350 mg, 91%) as a colorless powder. mp : 50-52 °C

[a] _D ²⁵ = -25.5 (c 1.0, CHC1 ₃ )

'H-NMR (500 MHz, CDCI3) δ : 7.75 (m, 2H), 7.62 (m, 2H), 7.38 (m, 2H), 7.30 (m, 2H), 7.06 (m, 4H), 6.77 (m, 4H), 6.49 (2 s, rotamer, 2H), 5.42-4.98 (complex m, 10H), 4.73^1.20 (complex m, 3H), 3.94 (m, 6H), 3.84 (m, 8H), 3.17-2.66 (complex m, 24H), 1.80-1.64 (complex m, 14H), 1.46- 1.25 (complex m, 100H), 1.00-0.77 (complex m, 33H).

HRMS (FAB, NBA matrix) m/z: 2276.5940 [(M+Na) ⁺ , calcd for CoeftieNeChoNa : 2276.5967]

A^MeLeu-D-Lac-A^MeLeu-D-morphPhLac-A^MeLeu-D-Lac-A^MeLeu- D- morphPhLac-O- TAGa

Following the procedure described for general procedure of Fmoc deprotection, 19 (114 mg, 0.0505 mmol) was converted to the corresponding amine (103 mg, 100%) as a colorless powder. mp : 45-47 °C [a] _D ²⁵ = -19.6 (c 1.0, CHC1 ₃ )

'H-NMR (500 MHz, CDCI3) δ : 7.76 (m, 4H), 6.79 (m, 4H), 6.48 (s, 2H), 5.50-4.96 (complex m, 9H), 3.94 (m, 6H), 3.83 (m, 8H), 3.30 (m, 1H), 3.16-2.74 (complex m, 21H), 2.38 (m, 3H), 1.80- 1.55 (complex m, 9H), 1.47-1.24 (complex m, 105H), 1.00-0.81 (complex m, 33 H).

HRMS (FAB, NBA matrix) m/z: 2032.5468 [(M+H) ⁺ , calcd for Ci2iH ₂ 07N ₆ Oi8 : 2032.5467] A^MeLeu-D-Lac-A^MeLeu-D-morphPhLac-A^MeLeu-D-Lac-A^MeLeu-D- morphPhLac-OH

Following the procedure described for general procedure of TAGa cleavage, A^MeLeu-D-Lac-A^ MeLeu-D-morphPhLac-^-MeLeu-D-Lac-^-MeLeu-D-morph- PhLac-O-TAGa (102 mg, 0.0502 mmol) was converted to the corresponding carboxylic acid. In the case of this substrate, the reaction required longer time than that of the general condition of TAGa cleavage (ca. 1 h). The reaction in 50% TFA/CH2CI2 at room temperature was needed to stir for 5 h to consume all of starting material, and gave desired product (-0.0502 mmol) as a crude oil, which was used next reaction without further purification.

Emodepside

Emodepside

(8 steps for longest linear from HO-TAGa)

38% overall yield from HO-TAGa

To a crude of carboxylic acid (-0.0502 mmol) in CH ₂ C1 ₂ (10 ml, 0.005 M) was added NN- diisopropylethylamine (60 μ∑, 0.351 mmol) and PyBOP (52 mg, 0.175 mmol) at room temperature. After stirring for 44 h, the reaction mixture was quenched with saturated aqueous NaHC03 (10 mL) at 0 °C and this mixture was extracted with CHCI3 (20 ml x 3). The combined organic layers were washed with 10% aqueous NaHSC>4 (60 ml) and brine (60 ml), dried over Na2SC>4, filtered and concentrated in vacuo. The crude was purified by column chromatography on silica gel (CHCI3 : MeOH = 400 : 1 to 100 : 1) to provide Emodepside (25 mg, 44% for 2 steps) as a light brown solid.

All physical data for synthetic Emodepside matched with the data of authentic compound. Comparative Example 1

A tag analogous to TAGa, but with C12 instead of Cis alkyl chains (C12-TAG), was prepared and coupled with N-Fmoc-N-MeLeu-D-Lac-OH (unit 1) according to the following reaction scheme: 1 -Bromododecane (3.© eq.)

2

(Cotortes 08)

f Purified by Silica gel Chromatograhy)

C12-TAG

{White solid)

(Purified by Silica gel Chromatograhy)

3

(Cotortes oil)

(Purified by Silica gel Chromatograhy)

Purification via silica gel chromatography was necessary after each reaction step. The compounds 2, C12-TAG and 3 did not crystallize in methanol. This is in contrast to, for example, the synthetic procedure for N-Fmoc-N-MeLeu-D-Lac-O-TAGa (section 2.1 above). The C12-TAG in this comparative example was not suitable for the intended tag-assisted synthesis and the further functionalization of compound 3 was not investigated further.

Comparative example 2

The commercially available CI -TAG was coupled with N-Fmoc-N-MeLeu-D-Lac-OH (unit 1) according to the following reaction scheme:

Purification via column chromatography was necessary after the reaction step. The compounds Cl- TAG and 6 did not crystallize in methanol. The CI -TAG in this comparative example was not suitable for the intended tag-assisted synthesis and the further functionalization of compound 6 was not investigated further.