Therapeutically, an antagonist that possesses both kinase selectivity for protein kinase C (PKC) and PKC isozyme selectivity is a potentially useful pharmacological agent. Hartenstein, J. H. et al. , "Perspectives in Medicinal Chemistry, " 99-118 (1993), VCH Publishers, New York. Such an antagonist of protein kinase C would be useful in treating disease states in which PKC has been implicated. Lester, D.S., et al., "Protein Kinase C: Current concepts and Future Perspectives", Ellis Horwood New York (1992) . Specific isozymes of protein kinase C have been implicated in cancer (Ahmed, et al. , ol. Pharma. , l, 858-86 (1993), CNS diseases such as Alzheimer's (Demaerschalck, et al . , Biochem. Biophvs. Acta. 1181. 214-218 (1993)), cardiovascular disease (Natarajan et al. Mol. Cell. Endo.. 1___L, 59-66 (1994)) and diabetic complications (King, et al., Proc. Nat. Acad. Sciences (USA) , -22, 11059-63 (1992)) .

Recently, a class of compounds, referred to herein as bis-indolylmaleimides, have been identified as potent and effective inhibitors of PKC. Compounds within this class are described, for example, in Davis et al., U.S. patent 5,057,614 (1991), Barth et al., European patent Application 397 060 (1992), Schultz et al., in PCT application WO 91/13070, Barth et al., U.S. patent 5,380,746, U.S. patent application serial number 08/163,060 (EP patent publication 0 657 458) , U.S. patent application serial number 08/324,948 (PCT patent publication WO 95/171,82), and U.S. patent application serial number 08/316,973 (EP patent publication 0 657 458) . This class of compound is generally represented by Formula I:

wherein X, Y and R represent optional substitutions.

The present invention provides a novel process for preparing compounds of the Formula I. More specifically, the invention provides an efficient process for reacting a alpha- keto indolyl acid of the Formula II:

wherein R ¹ is a hydrogen, C3 _. -C4 alkyl or benzyl, and R, X, and Y are optional substitutions; to produce a novel bis- indolylmaleic acid of the Formula III:

Compounds of the Formula III are readily converted to the bis- indolylmaleimide of Formula I .

Reductive dimerization with ketones and aldehydes to yield olefins on treatment with low-valent titanium reagents is

known in the art and generally described in J.E. McMurry, Chem. Rev. 89: 1513-24 (1989) . The reaction is also described in J.E. McMurry et al. , J. Am. Chem. Soc. 105: 1660-61 (1982), which demonstrates keto ester cyclization under similar conditions. However, before the present invention, it was unknown that low valent titanium effectively couples alpha keto indolyl acids of the Formula II. Thus, under the conditions described herein, the compounds of Formula I may be produced in an efficient process at high yield.

The invention provides a process of preparing a bis-indolylmaleic acid or ester thereof, which comprises:

Reacting indolyl acid of the Formula II:

wherein R ¹ is a hydrogen, C1-C4 alkyl or benzyl; and R, X, and Y are optional substitutions; in the presence of a low valent titanium reagent to form a bis-indolylmaleic acid or ester thereof the Formula III:

HI.

The invention further provides converting the bis- indolylmaleic acid to a bis-indolylmaleimide, which comprises:

Hydrolizing the acid of Formula III to form an anhydride of the Formula IV:

1ΛJ ( ) :iV) ; and

Converting the anhydride (IV) to a bis-indolyl maleimide of the Formula I.

For purposes of the present invention, as disclosed or claimed herein, the following terms are defined as follows.

The term "halo", as used herein, represents fluorine, chlorine, bromine, or iodine.

The term "C1-C4 alkyl" represents a cyclo, straight or branched chain alkyl group having from one to four carbon atoms such as methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, t-butyl and the like. A haloalkyl is one such alkyl substituted with one or more halo atoms, preferably one to three halo atoms. An example of a haloalkyl is trifluoromethyl . A C1-C4 alkoxy is a C1-C4 alkyl group covalently bonded by an -0- linkage. The term "aryl" represents a substituted or unsubstituted phenyl or naphthyl. Aryl may be optionally substituted with one or two groups independently selected from hydroxy, carboxy, C1-C4 alkoxy, C1-C4 alkyl, haloalkyl, nitro, -NR ⁴ R ⁵ , -NHCO(Cι-C4 alkyl) , -NHCO(benzyl) , -NHCO(phenyl) , SH, S(Cι*-C4 alkyl) , -OCO(Cι-C4 alkyl) , -S02(NR ⁴ R ⁵ ), -S02(Cι-C4 alkyl), -SO2 (phenyl) , or halo. The

term aryloxy is one such aryl covalently bonded by an -0- linkage. The term (CH2)π _\ aryl is preferably benzyl or phenyl.

The notation " " indicates an optional bond, i.e., X and Y are optionally bond together. (X) , (Y) , and R are optional subsitutions recognized in the art as being acceptable on pharmacologically active biε-indolylmaleimides. For example, in U.S. patent 5,057,614 herein incorporated by reference, (X) and (Y) independently signify hydrogen, alkyl, aryl, aralkyl, alkoxyalkyl, hydroxyalkyl, haloalkyl, aminoalkyl, monoalkylaminoalkyl, dialkylaminoalkyl, trialkylaminoalkyl, aminoalkylaminoalkyl, azidoalkyl, acylaminoalkyl, acylthioalkyl, alkylsulphonylaminoalkyl, arylsulphonylaminoalkyl, mercaptoalkyl, alkylthioalkyl, alkylsulphinylalkyl, alkylsulphonylalkyl, alkylsulphonyloxyalkyl, alkylcarbonyloxyalkyl, cyanoalkyl, amidinoalkyl, isothiocyanatoalkyl, glucopyranosyl, carboxyalkyl, alkoxycarbonylalkyl, aminocarbonylalkyl, hydroxyalkylthioalkyl, mercaptoalkylthioalkyl, arylthioalkyl or carboxyalkylithioalkyl. Similarly, R is hydrogen, halogen, alkyl, hydroxy, alkoxy, aryloxy, haloalkyl, nitro, amino, acylamino, monoalkylamino, dialkylamino, alkylthio, alkylsulphinyl or alkylsulphonyl. Other substituents accepted in the art for these positions may be found in U.S. patent 5,380,746, herein incorporated by reference.

In a preferred embodiment, X and Y are bonded together as disclosed in U.S. patent application serial number 08/316,973 (published as EP patent 0 657 458) . Most preferably, X and Y combine to form a six through nine atom macrocycle of the Formula la:

wherein:

Z is -0-, -S-, -NR3-, -CONH-, or -NHCO-; R is independently hydrogen, halo, C1-C4 alkyl, hydroxy, C1-C4 alkoxy, haloalkyl, nitro, NR ⁴ R ⁵ , or -NHCO(Cι- C4 alkyl) ;

R ² is hydrogen, C1-C4 alkyl, -(CH2)n l-C4 alkoxy, (CH2)na ^r ylf (C ^H 2)--aryloxy, - (CH2)n ^h ydroxy■ - (CH2) _n carboxy, -(CH2) _n COO(Cι-C4 alkyl), - (CH2) _n COO( (CH2) _n aryl) , -(CH2) _n CO(Cι-C4 alkyl), - (CH2) _n NR R ⁵ , - {CH2)NH (CF3) ,

-(CH2)N(CF3) (CH3) , (CH2) _n (NR R ⁵ ) (OR ⁴ ) , - (CH2) _n NH(CH2) _n aryl, -(CH2) _n H(CH2)nPyridyl, -(CH2) _n CONH( (CH2) _m aryl) , -(CH2) _n CONH(Cι-C4 alkyl), - (CH2) _n NHCO(C1 _. -C4 alkyl), - (CH2) _n NHCO(CH2) _n a yl - (CH2) _n OCONH(C1-C4 alkyl), -(CH2) _n OCONH(CH2) _n aryl, - (CH2) _n NHCOO(alkyl) ,

- (CH2) _n NHCOO(benzyl) , - (CH2) _1. HSO2 (C1-C4 alkyl), -(CH2) _n NHS02(CH2) _m aryl, -(CH2) _n CN, -(CH2) _n SH, - (CH2 ) _n S (C1-C4 alkyl), - (CH2) _n S (aryl) , - (CH2) _n Sθ2 ( R ⁴ R ⁵ ) , - (CH2) _n Sθ2 (C1 _. -C4 alkyl), or - (CH2) _n SO(C1-C4 alkyl) ; R3 is hydrogen, (CH2)na ^r yl or C1-C4 alkyl;

R ⁴ and R^ are independently hydrogen, methyl, phenyl, benzyl, or combine to the nitrogen to which they are bonded to form a saturated or unsaturated 5 or 6 membered ring,* and n is independently 1, 2 or 3.

The most preferred compounds of the Formula la are those wherein R is hydrogen; R ² is -CH2NR ⁴ R ⁵ ; n is 1; and R ⁴ and R5 are methyl.

Compounds of the Formula la are disclosed in U.S. patent application serial number 08/316,973 (published as EP patent 0 657 458) .

As noted above, the invention provides a process of preparing a bis-indolylmaleic acid, which comprises:

Reacting indolyl acid of the Formula II:

wherein R-*- is a hydrogen, C1-C alkyl or benzyl; and R, X, and Y are optional substitutions; in the presence of a low valent titanium reagent to form a bis-indolylmaleic acid of the Formula III:

The invention further provides converting the bis- indolylmaleic acid to a bis-mdolylmaleimide, which comprises: Hydrolizing the compound of Formula III to form an anhydride of the Formula IV:

Converting the anhydride (IV) to a bis-indolyl maleimide of the Formula I.

The preparation of a bis-indolyl acid of the Formula II is carried out as follows:

Scheme 1

(V) ιι:

In the above Scheme 1, R ¹ , R, X and Y are the same as previously defined. Preferably, R ¹ is a C1-C4 alkyl. Formation of the indolyl acid of the Formula II is carried out under conditions recognized in the art and described in G.W. Gibble et al . , J. Orα. Chem. 57: 3636-42 (1992); M. Giua et al . , Chim. Ital . 54. 593 (1924) ; M.E. Speeter et al., J. Am. Chem. Soc. 76: 6208 (1954) ; and A.G. Gudmundson et al., J. Orα. Chem. 23: 1171 (1958) .

Preferably, a compound of the Formula V is reacted dropwise with about two to twenty equivelents of oxalyl chloride at -30° C to ambient temperature in an inert solvent, such as ether or THF, to form 3-indolylglyoxylyl chloride. The reaction is quenched with methanol . The product is precipated by the addition of acid, collected, resuspended and neutralized by the addition of base to form the compound of Formula II .

The compound of Formula II is then reacted in a novel process in accordance with Scheme 2.

S heme 2

(ID (III)

Scheme 2 describes the reaction of a compound of the Formula II with a low-valent titanium reagent to form a compound of the Formula III. The reaction is carried out in one or more inert solvents recognized to one skilled in the art. For example, the reaction may be carried out in one or more of the following solvents: ether, THF, methylene chloride, DMF, DME, or pyridine. Preferably, the solvent is DME, methylene chloride and THF.

The reaction of Scheme 2 is carried out with from about 2 to about 40 equivalents of the low-valent titanium reagent per mole of Compound II. Preferably, the reaction is carried out with 2 to 20 equivalents of the low-valent titanium reagent per mole of Compound II. The reaction is operable from -20°C to the reflux temperature of the reaction mixture. Preferably, the reaction is carried out from 0°C to the reflux temperature. The reaction is generally complete from about 10 minutes to about 48 hours. A low- valent titanium reagent is titanium in its

Ti(O), Ti(I), Ti(II) oxidation state or a mixture of these oxidation states. The reagent is prepared in si tu by reacting TiCl3 or TiCl4 with a second reducing agent capable of reducing titanium to its Ti(O), Till) , Ti(II) oxidation state or a mixture of these oxidation states. Thus, acceptable second reducing agents include LiAlH4, Li, Zn-Cu, Zn, and the like. Preferred reducing agents include Zn and

Zn-Cu. Zn-Fe is also operable when added subsequent to the addition of TiCl3. The preferred reducing agents are Zn and Zn-Cu. The amount of reducing agent necessary is dependent on the reducing agent selected and the reaction conditions. Generally, 15 mg to 1500 mg reducing agent per mmol TiCl3, preferably 75 mg to 500 mg reducing agent per mole TiCl3 are operable.

Table 1 demonstrates the reaction with various reducing agents . Table 1

Reductive Coupling usinσ

In the above Table 1, all reactions were carried out at room temperature. Reactions 1, 2, 3, 6, and 7 were run in DME.

Reaction 4 and 5 were run in 25% CH2CI2 in DME. In Reaction 4 and 5, Compound II in DME/CH2CI2 (4:1) was added to a stirred slurry of TiCl3 and Zn over 10 hours. In reaction 6 and 7, TiCl3, Compound II and Zn were suspended in DME and stirred. Table 1 demonstrates that the reducing agent employed is not critical to the present invention. One skilled in the art would recognize, by varying the reaction parameters, such as the order of addition and time of reaction, any reducing agent capable of reducing titanium to its low-valent oxidation states is operable.

Surprisingly, it has been discovered that the novel reaction described herein proceeds without the addition of

- li ¬ the second reducing agent. That is, the reaction of scheme 2 may be carried out with TiCl3 using 2 to 500 equivalents of TiCl3 without the addition of a second reducing agent such as Zn, Zn-Cu, and Zn-Fe. The reaction is carried out in an inert solvent at temperatures ranging from -40°C to the reflux temperature of the reaction mixture. Most preferably, the reaction is carried out from -30°C to room temperature using 2 to 10 equivalents of TiCl3. Carrying out the reaction in the absence of the second reducing agent is preferred to further minimize any over reduction of the 3- indolyl-α keto ester to the 3-indolyl acetic acid ester.

The novel intermediate (III) may be isolated and purified by standard techniques including chromatography, trituration, crystallization, filtration, or a combination of these or other techniques recognized in the art.

The compound of Formula III is readily converted to the bis-indolylmaleimide of Formula I in accordance with in Scheme 3.

Scheme 3

(III) (I)

In the above scheme R-*-, R, X and Y are the same as previously defined. The compound of the Formula III is hydrolized under strongly acidic or basic conditions to form an anhydride of the Formula IV:

:ιv)

The conditions necessary to hydrolize the compound of Formula III to form the anhydride are appreciated in the art for hydrolyzing an ester. Preferably, the anhydride is formed using a base, such as sodium hydroxide, in an aqueous solvent followed by acidic work-up conditions.

The anhydride of Formula IV is converted to the bis-indolyl maleimide of the Formula I by techniques appreciated in the art and described in P.D. Davis et al. , Tetrahedron Lett. 31: 5201-04 (1990) and U.S. patent 5,057,614. For example, the anhydride is reacted with an excess of hexamethyldisilazane or an ammonium salt (ammonium acetate, bromide, or chloride) and C1-C4 alcohol (preferably methanol) in an polar aprotic solvent such as DMF at room temperature. Preferably, the hexamethyldisilazane or an ammonium salt is reacted at a ratio greater than about 5:1 equivalents of anhydride.

As previously stated, the reaction of ketones and aldehydes to undergo a reductive dimerization to yield olefins in the presence of low-valent titanium reagents is known in the art and generally described in J.E. McMurry et al., Chem. Rev. 89: 1513-24 (1989) . however, before the present invention, it was unknown that low valent titanium effectively couples alpha keto indolyl acids of the Formula

II in high yield. Under the conditions described herein, the reaction proceeds in a chemoselective manner. The chemoselectivity of the reaction is quite surprising in view of J.E. McMurry et al . , J. Am. Chem. Soc. 105: 1660-61 (1982), which demonstrates keto ester cyclization under similar conditions to form a cycloalkanone. Furthermore,

except when X and Y are bonded together and comprise five or fewer atoms, over reduction of the 3-indolyl-α keto ester to the 3-indolyl acetic acid ester is not observed.

Thus, the present process is useful in preparing compounds of the Formula I. The compounds of the Formula I are PKC inhibitors and useful in treating diseases implicated by PKC, particularly diabetes mellitus and, more specifically, diabetic complications. The amount of compound of Formula I administered is an amount that is capable of inhibiting PKC activity in mammals. The particular dose of the compound administered according to this invention will, of course, be determined by the particular circumstances surrounding the case, including the compound administered, the route of administration, the particular condition being treated, and similar considerations.

The following examples and preparations are provided merely to further illustrate the invention. The scope of the invention is not construed as merely consisting of the following examples. In the following examples and preparations, melting point, nuclear magnetic resonance spectra, mass spectra, high pressure liquid chromatography over silica gel, N,N-dimethylformamide, palladium on charcoal, tetrahydrofuran, and ethyl acetate are abbreviated M.Pt., NMR, MS, HPLC, DMF, Pd/C, THF, and EtOAc respectively. The terms "NMR" and "MS" indicate that the spectrum was consistent with the desired structure.

Preparation 1 l-S BisindQie hexane

A dry 3 necked flask equipped with reflux condenser was charged with NaH (2.70 g, 68 mmol, 60% dispersion in oil)

that was washed with hexane to remove oil. Washed NaH was then suspended in DMF (40 mL) and stirred vigorously at 0° C . To this suspension was added indole (5.3 g, 45 mmol) in DMF (40 mL) over a period of 5 minutes. The resulting mixture was stirred for 1 hour at 0° C followed by dropwise addition of 1,6 dibromide hexane (3.5 mL, 22.5 mmol) in DMF (40 mL) over a period of 30 minutes. This mixture was then allowed to warm to room temperature and stirred overnight. Excess NaH was destroyed by the addition of excess MeOH. The mixture was then extracted with ether (250 mL x ) . The combined organic phase was washed with brine (20 mL) followed by drying over MgSθ4 and concentrated to provide crude product that was passed through a short silica column (eluted with 5% ethyl acetate in hexane) to afford pure 1-6-Bis- indole hexane (6.84 g, 96%) . MS. ---H NMR (CDI3) δ 7.66 (d,J = 10Hz, 2H, C-2 indole) , 7.56-7.03

(m, 6H, indole), 6.50 (d, 2H, C-3 indole) , 4.06 (t,J = 7 Hz 4H, NCH2(CH2)4CH2N) , 1.90-1.73 9m, 4H, NCH2CH2 (CH2) 2CH2CH2N) , 1.36-1.26 (m, 4H, N(CH2)CH2CH2 (CH2 ) 2N) .

Preparation 2 1.6 bis(3-Methvlαlvoxate indole) hexane

To a stirred solution of 1, 6-bis (3-Methylglydxate indole) hexane (2.00 g, 6.31 mmol) in THF (65 mL) at 0°C was added oxalyl chloride (1.4 mL, 15.79 mmol) dropwise over a period of 5 minutes. The resulting solution was then stirred for 3 hours when TLC analysis of the reaction mixture

indicated consumption of starting material. It was necessary to quench an aliquot of the reaction mixture with MeOH and analyze by TLC (25% ethyl acetate in hexane) to make sure the intermediate mono methoxylated starting material was converted to final product. The mixture was acidified with HCl to pH 3 when the HCl salt of the product precipitated. These precipitate were filtered and washed with hexane. These washed precipitate were then suspended in THF and 1M NaOH was added until pH was -7 when the suspension turned clear. The resulting solution was extracted with ethyl acetate (50 mL x 3), dried over MgSO ^" 4 and concentrated under reduced pressure to yield crude product that was purified by passing through a short silica column eluted with 50% ethyl acetate in hexane to yield pure 1, 6-bis (3-Methylglyoxate indole) hexane (3.12 g, 80%) . MS. - ^• H NMR (CDCI3) 5 8.50-8.43 (m, 2H, C-7 indole) , 7.40-7.30 (m,

6H, indole), 4.16 (t,J = 7 Hz, 4H, NCH2 (CH2) 4CH2N) , 3.96 (s, 6H, COOCH3), 1.96-1.83 (m, 4H, NCH2CH2 (CH2)2 H2N) , 1.43-1.30 (m, 4H, (CH2)2 H2CH2 (CH2)2N) .

Preparation 3 1, 7-Bisindole heptane

A dry 250 mL round bottom flask with a magnetic stirrer was charged with a 60% dispersion of NaH in oil (4.02 g, 100.60 mmol) . Excess oil was then washed using dry hexane (-10 mL) followed by addition of dry DMF (150 mL) . The resulting slurry was cooled to 0° C using icebath followed by dropwise addition of indole (9.06 g, 77.42 mmol) in DMF (50 mL) . The reaction mixture was allowed to warm up to the room temperature and stirred for 1 hour. To this mixture was

added 1-7 dibromoheptane (10 g, 38.71 mmol) over 5 minutes. The resulting mixture was stirred for additional 24 hours followed by dropwise addition of water (-20 mL) and extraction with ether (50 mL x 3) . The combined organic phases were washed with brine (50 mL) , dried over MgS04 and concentration under reduced pressure to yield crude product. This crude product was cleaned by passing through a short silica column that was eluted with 10% ethyl acetate in hexane to afford pure 1, 7-bisindole heptane (11.5 g, 90%) . MS. ---H NMR (CDCI3, 250 MHz) δ 7.83 (d, J = 7.50 Hz, 2H, Ar) ,

7.52-7.14 (m, 8H, Ar) , 6.68 (d, J = 5.00 Hz, 2H, Ar) , 4.18 (t, J = 6.87 Hz, 4H, NCH2 (CH2)5CH2N) , 2.00-1.82 (m, 4H, NCH2CH2 (CH2)3CH2CH2 ) , 1.44-1.33 (m, 4H, N(CH2)2 H2CH2CH2 (CH2)2N) , 1.18-1.00 (m, 2H, N ⁽ CH2 ⁾ 3CH2(CH2)3N) *

Preparation 4 1.7-bis(3-Methvlαlvoxate indole) heptane

To a stirred solution of bisindole heptane (2 g, 6.31 mmol) in THF (65 mL) was added at 0° C oxalylchloride (1.4 mL, 15.79 mmol) dropwise over a period of 5 minutes. The mixture was stirred for 3 hours at 0° C when TLC indicated the complete consumption of starting material. The reaction was then quenched with MeOH (766 μL, 18.93 mmol) and stirred for additional 1 hour. This mixture was acidified to pH 1 with 0.2 N aqueous HCl when the product precipitated out of the solution. These precipitates were filtered and washed with water to completely remove HCl followed by air drying to give pure product (3.12 g, 80%) . MS.

^• LH NMR (CDCI ₃ , 250 MHz) δ. 8.48-8.39 ( , 2H, Ar) , 8.32 (s, 2H,

Ar) , 7.36-7.27 (m, 6H, Ar) , 4.10 (t, J = 8.25 Hz, 4H, NCH ₂ (CH ₂ )5CH ₂ N) , 3.92 (s, 6H, COOCH3 ) , 1.93-1.78 (m, 4H, NCH ₂ CH ₂ (CH ₂ )3CH ₂ CH2N) , 1.38-1.22 (m, 6H, NCH ₂ CH ₂ (CH ₂ ) ₃ CH ₂ CH ₃ N

Preparation 5

Pislnflple-tri-.yl ether

To a stirred slurry of NaH (6.08g, 0.15 mol, 60% dispersion) in dry DMF (100 mL) at 0° C was added a solution of indole (8.92 g, 0.07 mol) in DMF (200 mL) over 5 min via cannula. The resulting mixture was stirred for lh at room temperature at which time a solution of bismesylate (10.40 g, 0.02 mol) in CH ₂ CI ₂ (200 mL) was added over a period of 10 min via cannula. This mixture was then stirred overnight at which time the TLC analysis indicated the complete consumption of the starting material. The reaction was quenched with saturated aqueous NH ₄ CI (100 mL) followed by dilution with ether (500 mL) . The organic phase was separated and the aqueous phase was further extracted with ether (100 mL x 3) . The combine organic phase was then washed once with brine (100 mL) , dried over MgS0 ₄ , filtered and concentrated under reduced pressure to yield crude product that was purified by HPLC to give pure bisindole (10.02g, 85%) . MS. ¹ H NMR (CDCI ₃ ) 67.72-6.92 (m, 23H, Ar) , 6.56 (d, J = 4.9 Hz,

1H, Ar) , 6.48 (d, J = 4.9 Hz, 1H, Ar) , 6.31 (d, J = 4.9 Hz, 1H, Ar) , 4.36-4.26 (m, 2H, NCH2CH ₂ O) , 3.98-3.76 (m, 3H, CH CH ₂ CH and NCH CH ₂ 0) , 3.63-3.33 (m, 1H, NCH ₂ CH ₂ 0) , 3.16-

SUBSTΓΓUTE SHEET (RULE 26)

3.03 ( , 3H, OCHCtf_-OTr and OCHCH ₂ OTr) , 2.03-1.89 !m, 2H,

CH ₂ CH2CH(CH ₂ -)0) .

Preparation 6

Bis (3-methylαlvoxalate-indole) -trityl ether

To a stirred solution of bisindole (70 mg, 0.11 mmol) in dry THF (5 mL) at 0 °C was added TEA (100 μL, 0.70 mmol) followed by addition of (COCl) ₂ (30 μL, 0.35 mmol) . The resulting mixture was stirred for 4 h at which time the TLC analysis (1:1 ethyl acetate/hexane) indicated the complete consumption of the starting material. The reaction was then quenched with MeOH (5 mL) . The resulting mixture was stirred over night at room temperature after which it was concentrated under reduced pressure. The residue was re dissolved in ethyl acetate (10 mL) and washed with water (5 mL) followed by brine (5 mL) . This organic phase was then dried over MgS0 ₄ , filtered and concentrated under reduced pressure to yield crude product that was cleaned by silica gel chromatography to afford pure product (21 mg, 30%) . MS. ⁱ H NMR (CDC1 ₃ ) δ8.53 (s, IH, Ar), 8.49-8.36 (m, 2H, Ar) , 8.15

(s, IH, Ar) , 7.49-7.06 (m, 20H, Ar) , 7.00-6.93 (m, IH, Ar) , 4.36-4.26 (m, 2H, NCH ₂ CH ₂ O) , 4.16-3.76 (m, 9H, COOCH ₃ , COOCH ₃ , NCH ₂ CH ₂ CH, NCH ₂ CH ₂ 0) , 3.69-3.56 (m, IH, NCH ₂ CH ₂ O) , 3.16-3.00 (m, 3H, OCH(CH ₂ OTr)CH ₂ , OCH (CH ₂ OTr) CH ₂ , 2.06-1.93 (m, 2H, CHCH ₂ CH ₂ N) .

Preparation 7 Bisindole alcohol

To a stirred solution of bisindole (6.82 g, 0.01 mol) in CH ₂ CI ₂ (50 mL) and MeOH (50 mL) at room temperature was added a few drops of cone. HCl. The resulting solution, which turned purple red, was stirred until TLC analysis (50% ethyl acetate in hexane) indicated complete consumption of starting material. The reaction was quenched by addition of saturated aqueous NaHC0 ₃ followed by concentration under reduced pressure to give oily residue that was dissolved in ethyl acetate (100 mL) and washed with water (50 mL x 3 ) and brine (50 mL) . The organic phase was then dried over MgS0 ₄ , filtered and concentrated to give crude bisindole alcohol that was passed through a short silica pat (10% ethyl acetate in hexane to ethyl acetate) to give pure alcohol (3.50, 87%) . MS. --H NMR (CDCI ₃ ) δ7.73-7.56 (m, 2H, Ar) , 7.46-7.00 (m, 7H, Ar) ,

6.61 (d, J = 4.9 Hz, IH, Ar) , 6.58 (d, J = 4.9 Hz, IH, Ar) , 6.38 ( (d, J = 4.9 Hz, IH, Ar) , 4.63 (t, J = 7.4 Hz, 2H, NCi-2CH ₂ 0) , 4.09-3.08 (m, 3H, NCH_-CH ₂ CH and NCH ₂ Ci__>0) , 3.74- 3.66 (m, IH, NCH2CH2O) , 3.54 - 3.44 (m, IH, OCH (CH2OH) CH ₂ ) , 3.37-3.24 (m, IH, OCH (CH ₂ OH ) CH ₂ ) , 3.13-3.03 (m, IH, OCH(CH ₂ OH)CH ₂ ) , 2.06-1.86 (m, 2H, NCH2CH2CH) .

Preparation 8 Bisindole-dimethvlamin

To a stirred solution of alcohol (1 g, 2.87 mmol) in CH ₂ C1 ₂ (20 mL) at 0° C was added pyridine (2 mL) followed by solid methane sulfonic anhydride (650 mg, 3.73 mmol) . The resulting mixture was slowly allowed to warm to room temperature over 30 min at which time the TLC analysis (50% ethyl acetate in hexane) indicated the formation of a new less polar product at the expense of starting material. After another 30 min, the starting material was completely consumed as indicated by TLC analysis. The reaction was stopped by addition of saturated aqueous NH ₄ CI solution (10 mL) followed by separation of the organic phase. The resulting organic phase was extracted with CH ₂ C1 ₂ (5 mL x 3) . The combine organic phase was dried over MgSθ ₄ , filtered and concentrated under reduced pressure to give crude product that was purified by passing through a short silica pat to give clean bisindole methylsulfone (968 mg, 79%) .

A stirred suspension of bisindole methylsulfonate (968 mg, 2.27 mmol) in 40% aqueous dimethylamine (10 mL) in a sealed flask was heated to 50° C for 16 h. The reaction mixture was then concentrated in vacou to give oily residue that was dissolved in dissolved in CH ₂ CI ₂ (25 mL) . The solution was washed with water (10 mL x 2 ) , dried over MgS0 , filtered and concentrated under reduced pressure to yield crude product that was purified by column chromatography on silica gel using ethyl acetate as initial elutant followed by

10% methanol in CH ₂ CI ₂ to give clean bisindole dimethylamine

(773 mg, 90%) . MS.

-•H NMR (CDCI ₃ ) δ7.66-7.55 (m, 2H, Ar) , 7.40-7.33 (m, IH, Ar) ,

7.26-7.03 (m, 6H, Ar) , 7.22 (d, J = 4.9 Hz, IH, Ar) , 6.51 (d, J = 4.9 Hz, IH, Ar), 6.38 (d, J = 4.9 Hz, IH, Ar) , 4.34-4.26 (m, 2H, NCH2CH2O) , 3.96-3.80 (m, 3H, NCH-.CH ₂ CH and NCH2CH2O) , 3.73-3.63 (m, IH, nCH ₂ Ctf2θ) , 3.58-3.49 (m, IH, OCfiCH ₂ ) , 2.76 (s, 3H, NCHj), 2.68, (s, 3H, NCH3) , 2.40-2.33 (m, 2H, CHCF ^* T2N(CH ₃ ) , 2.09-1.83 (m, 2H, NCH2CH2CH) .

Preparation 9 Bis (3 -methvlσlvoxalate- indole) -dimethvlamine

To a stirred solution of bisindole dimethylamine (1.37 g, 3.69 mmol) in THF (25 mL) at 0° C was added (COCU ₂ ,(1.6 mL, 18.45 mmol) over 3 min. The resulting solution was stirred at 0 °C for 4 h at which time the TLC analysis (30% MeOH in CHCI ₃ ) showed the complete consumption of the starting material. The reaction was quenched by addition of MeOH (25 mL) followed by stirring of the resulting reaction mixture over night at room temperature. The reaction was concentrated under reduced pressure to dryness. The residue was re dissolved in MeOH (5 mL) and water (20 mL) and pH of this solution was adjusted to 8 by addition of 0.02N NaOH. The resulting mixture was quickly extracted with CH ₂ C1 ₂ (20 mL x 4) . The combined organic phase was dried over MgS0 ₄ , concentrated and purified by column chromatography to yield pure product (3.17 g, 86%) . MS.

¹ H NMR (CDCI3) δ8.54 (s, IH, Indole C-2) , 8.49-8.40 (m, 2H, Ar) , 8.28 (s, IH, Indole C-2) , 7.46-7.26 (m, 4H, Ar) , 7.20

(t, J = 7.5 Hz, IH, Ar) , 7.09 (d, J = 9.9 Hz, IH, Ar) , 4.43- 4.36 (m, 2H, NCH2CH2O) , 4.16-3.99 (m, 3H, NCH CH2CH and NCK ₂ CH ₂ 0) , 3.96 (s, 3H, OOCH3) , 3.92 (s, 3H, OOCH ₃ ) , 3.69-3.23

(m, IH, OCH(CH ₂ -)CH ₂ ) .

Preparation 10 Bisindole-tert-butvldiphenvlsilvl ether

To a stirred solution alcohol (500 mg, 1.43 mmol) in CH ₂ CI ₂ (10 mL) was added solid imidazole (195 mg, 2.86 mmol) followed by addition of TPSCl (510 mg, 1.85 mmol) in CH ₂ CI ₂ (2 mL) . The resulting solution was stirred over night after which the imidazole hydrochloride was filtered off. The filtrate was diluted ether (20 mL) and washed with water (10 mL x 2) and brine (10 mL) . The resulting organic phase was dried over MgS0 ₄ , filtered and concentrated under reduced pressure to provide crude product that was purified by silica gel chromatography to yield pure silyl ether (789 mg, 94%) .

MS.

-H NMR {CDCI ₃ ) δ 7.76-6.93 (m, 19 H, Ar) , 6.51 (d, 4.9 Hz , IH, Ar) , 6.43 (d, 4.9 Hz, IH, Ar) , 6.29 (d, 4.9 Hz, IH, Ar) ,

4.26-4.20 (m, 2H, NCH2CH2O) , 3.97-3.69 (m, 3H, NCH2CH2CH and NCH2CH2O) , 3.56-3.41 (m, 3H, CH2CH2O and CH2OTPS , 3.03-2.93 (m, IH, OCH(CH ₂ -)CH ₂ ) , 2.09-1.94 (m, IH, NCH2CH2CH) , 1.89-1.76 (m, IH, NCH2CH2CH) , 0.96 (s, 9H, OSiC (CH3) 3 ) *

Preparation 11 Bis (3-methvJσlvoxalate-indole) -tert-butvldiphenvlsilvl ether

To a stirred solution of TPS ether (621 mg, 1.05 mmol) in THF (20 mL) was added TEA (1.5 mL, 10.5 mmol) followed by addition of (COCD ₂ (275 mL, 3.15 mmol) over -2 min. The resulting mixture was stirred for 4 h at 0 °C at which time the TLC analysis (1:1 ethyl acetate/hexane) indicated the complete consumption of the starting material. The reaction was quenched by addition of MeOH (10 mL) and the resulting mixture was stirred over night at room temperature. The reaction mixture was concentrated to dryness and the residue was re dissolved in ethyl acetate (20 mL) . This solution was washed with water (10 mL x 3) and brine (10 mL) . The resulting organic phase was dried over MgSθ ₄ , filtered and concentrated under reduced pressure to yield crude product that was purified by column chromatography to yield clean product (527 mg, 66%) . MS. -•H NMR (CDCI ₃ ) 68.50 (s, IH, Indole C-2), 8.48-8.38 (m, 2H, Ar) , 8.20 (s, IH, Indole C-2), 7.56-7.44 (m, 4H, Ar) , 7.43-

7.24 (m, 10H, Ar) , 7.11 (t, 7.5 Hz, IH, Ar) , 6.96 (d, J = 9.9 Hz, IH, Ar) , 4.31-4.24 (m, 2H, NCH ₂ CH ₂ 0) , 4.06-3.08 (m, 9H, COOCJ-/3, COOHj, NCH2CH2CH and NCH ₂ CH ₂ 0) , 3.60-1.88 (m, 2H, NCH ₂ CH) , 0.96 (s, 9H, OSiC (CH ₃ ) ₃ ) .

Example 1 Macrocvclic Diester

To a stirred slurry of Zn-Cu couple (60 mg) in DME (15 mL) was added TiCl3 (400 mL, 0.4 mmol, 1M solution in 2:1 CH2/CI2 :THF) . The resulting mixture was stirred for 10 minutes followed by addition of diketone (53 mg, 0.1 mmol) in DME (10 mL) . The mixture was stirred at room temperature for 1 hour when tic analysis of the reaction mixture indicated the complete consumption of starting material. The mixture was stirred for another 1 hour followed by quenching the mixture with aqueous NaHCθ3 (2 mL) and aqueous EDTA. The mixture was then diluted with ethyl acetate, organic phase separated and aqueous phase extracted with ethyl acetate (10 mL x 3) . The combine organic phase was dried over MgSθ4, concentrated under reduced pressure to afford crude product (48 mg material balance) that was purified by column chromatography using 10% ethyl acetate in hexane to yield pure product (21.8 mg, 48%) . MS. - ^• -H NMR (300 MHz, CDI3) δ 7.56-7.50 (m, 2H,C-7 indole), 7.36-

7.33 (m, 6H, indole), 6.70 (s, 2H, C-3 indole), 4.03-3.96 (m, 4H, NCH2 (CH2UCH2N) , 3.86 (s, 6H, COOH3 ) , 1.90-1.80 (m, 4H, NCH2CH2 (CH2>2CH2 ) , 1.03-0.96 (m, 4H, N(CH2) 2CH2CH2 (CH2)2N) . IF. ^v max 1716 α-βunsa . COOMe str.)

Example 2 Macrocvclic Anhydride

To a stirred solution of bismethyl ester (105 mg, 0.22 mmol) in dioxane (10 mL) and MeOH (lOmL) was added aqueous 5N NaOH solution (4 mL) . The reaction mixture was stirred overnight at 50° C followed by acifying with concentrated HCl to pH 1. This resulting mixture was then extracted with ethyl acetate (10 mL x 4) . The combined organic phase, that was deep red in colour, was dried over MgS0 ₄ and concentrated under reduced pressure to yield crude anhydride. This crude anhydride was cleaned by passing through a short silica column that was eluted with ethyl acetate to obtained pure macrocyclic anhydride (66 mg, 73%) .

MS. ^λ K NMR (CDCI ₃ , 300 MHz) δ 8.01-8.00 (m, 2H, Ar) , 7.38-7.25 (m,

8H, Ar) , 4.12-4.08 (m, 4H, NCH (CH ) 4CH2N) , 1.95-1.92 (m, 4H, NCH ₂ CH2(CH2)2CH ₂ CH2N) , 1.19-1.18 (m, N (CH ₂ ) 2CH ₂ CH ₂ (CH ₂ ) N) .

Example 3 Macrocvclic maleimide

To a stirred solution of Macrocyclic anhydride (66 mg, 0.16 mmol) in dry DMF (15 mL) was added hexamethyldisilazane (340 mL, 1.60 mmol) followed by addition of MeOH (32 mL, 0.8 mmol) . The resulting reaction mixture was stirred for 48 hours at 50° C when the tic (25% ethyl acetate in hexane) analysis of reaction mixture indicated the complete comsumption of starting material. The reaction mixture was then concentrated under reduced pressure, the residue redissolved in EtOAc (20 mL) that was washed once with water (10 mL) and brine (10 mL) . The resulting organic phase was dried over MgS0 ₄ followed by concentration under reduced pressure to yield crude macrocyclic maleimide that was cleaned by passing through a short silica column eluting with ethyl acetate to afford pure maleimide (47 mg, 73%) . MS. NMR.

¹ H NMR (CDC1 ₃ , 300 MHz) δ 8.00-7.97 (m, 2H, Ar) , 7.35-7.10 (m, 8H, Ar) , 4.13-3.96 (m, 4H, NCH ₂ (CH ₂ ) ₄ CH ₂ N) , 2.00-1.86 (m, 2H, NCH ₂ CH ₂ (CH ₂ ) ₂ H ₂ CH ₂ N) , 1.23-1.06 (m, 2H, (CH ₂ ) ₂ CH ₂ CH ₂ (CH ₂ ) ₂ N) .

Example 4 Macrocvclic diester

To a stirred slurry to Zn-Cu couple (103 mg, 1.59 mmol) in DME (10 mL) was added 1M solution of TiCl ₃ (790 μL, 0.79 mmol) in CH ₂ CI ₂ and THF (2:1) . The resulting dark coloured solution was stirred for 10 minutes when 1,7-bis (3- Methylglyoxate indole) heptane (100 mg, 0.19 mmol) in DME (10 mL) was added to it all at once. This reaction mixture was then stirred overnight at room temperature. The reaction was

stopped by addition of water (2 mL) followed by dilution with ethyl acetate (20 mL) . To the resulting mixture was added aqueous sat. K ₂ CO ₃ (20 mL) and was extracted with ethyl acetate (20 mL x 4) . The extract was washed with water (10 mL x 2) and brine (10 mL) followed by drying over MgSθ ₄ . This dried organic phase was then concentrated under reduced pressure followed by purification by column chromatography on silica gel eluting the column with 10% ethyl acetate in hexane followed by 25% ethyl acetate in hexane to afford the pure seven carbon linked macrocycle (38 mg, 43%) . ^λ K NMR (CDCI ₃ , 250 MHz) δ 7.61-7.53 (m, 2H, Ar) , 7.32-7.02 (m,

6H, Ar) , 6.75 (s, 2H, Ar) , 3.95-3.88 (m, 4H, NCH ₂ (CH ₂ ) ₅ CH ₂ N) , 3.82 (s, 6H, COOCH ₃ ), 1.88-1.72 (m, 4H, NCH ₂ CH ₂ (CH ₂ ) ₃ CH ₂ CH ₂ N) , 1.60-1.44 (m, 6H, NCH ₂ CH ₂ (CH ₂ ) ₃ CH ₂ CH ₂ N) .

Example 5 Macrocvclization-tritvl ether

To a stirred solution of diketone (100 mg, 0.13 mmol) dry DME (5 mL) at -30 °C was added 1M THF/CH ₂ C1 ₂ (2 :1) solution of TiCl ₃ (500 μL, 0.50 mmol) all at once. The resulting reaction mixture was allowed to warm up to room temperature by itself (~2h) at which time TLC analysis indicated the complete consumption of the starting material and a new less polar product. The reaction was quenched with aqueous NaHC0 ₃ (2 mL) followed by extraction with EtOAc ( 5 mL x 3) . The combined organic phase was washed once with aqueous NaCl (5 mL) , dried over MgS0 ₄ , filtered and concentrated under reduced pressure to yield crude product

that was cleaned by column chromatography to yield clean macrocycle (< 1 mg) . FD-MS : Calcd for C47H42N2O6: 730.8, found: 730.7.

Example 6 Macrocvclization-dimethyl amine

To a stirred solution of diketone (100 mg, 0.18 mmol) dry DME (5 mL) at -30 °C was added 1M THF/CH ₂ CI ₂ (2:1) solution of TiCl ₃ (750 μL, 0.75 mmol) all at once. The resulting reaction mixture was allowed to warm up to room temperature by itself (~2h) at which time TLC analysis indicated the complete consumption of the starting material and a new less polar product. The reaction was quenched with aqueous NaHCθ ₃ (2 mL) followed by extraction with EtOAc ( 5 mL x 3 ) . The combined organic phase was washed once with aqueous NaCl (5 mL) , dried over MgSθ ₄ , filtered and concentrated under reduced pressure to yield crude product that was cleaned by column chromatography to yield clean macrocycle (23 mg, 24%) . MS. ¹ H NMR (CDCI ₃ ) δ 7.67-6.93 ( , 8H, Ar) , 6.78 (s, IH, Indole C-

3), 6.49 (s, IH, Indole C-3 ⁾ , 4.34-3.43 (m, 12H, COOCH ₃ ,

COOCH ₃ and NCH ₂ CH ₂ OCHCH ₂ CH ₂ N) 2.36-1.91 (m, 10H, NCH ₂ CH ₂ CH and CH ₂ N(CH ₃ ) ₂ ) .

Example 7 Macrocvlization-tert-butvldiphenvlsilvl ether

To a stirred solution of diketone (100 mg, 0.13 mmol) dry DME (5 mL) at -30 °C was added 1M THF/CH ₂ CI ₂ (2:1) solution of TiCl ₃ (500 μL, 0.50 mmol) all at once. The resulting reaction mixture was allowed to warm up to room temperature by itself (~2h) at which time TLC analysis indicated the complete consumption of the starting material and a new less polar product. The reaction was quenched with aqueous NaHC0 ₃ (2 mL) followed by extraction with EtOAc ( 5 mL x 3) . The combined organic phase was washed once with aqueous NaCl (5 mL) , dried over MgS0 ₄ , filtered and concentrated under reduced pressure to yield crude product that was cleaned by column chromatography to yield clean macrocycle (37 mg, 40%). MS. ¹ H NMR (CDCI ₃ ) δ7.66-7.07 (m, 18 H, Ar) , 6.69 (s, IH, Indole C-2), 6.36 (s, IH, Indole C-2) 4.03-3.36 (m, 14H, NCH ₂ CH ₂ OCH (CH ₂ OTPS)CH ₂ CH ₂ N) , COOCH ₃ , COOCH ₃ ) , 3.09-3.00 (m, IH, NCH ₂ CH ₂ CH) , 1.91-1.80 (m, IH, NCH ₂ CH ₂ CH) , 0.96 (s, 9H, OSiC(CH ₃ ) ₃ ) .