WANG YAPING (CN)
SPINDLER FELIX (CH)
PUGIN BENOIT (CH)
FENG XIANGDONG (CH)
WEISSENSTEINER WALTER (AT)
WANG YAPING (CN)
SPINDLER FELIX (CH)
PUGIN BENOIT (CH)
FENG XIANGDONG (CH)
| WO2001038336A1 | 2001-05-31 |
Claims
1. Compounds of the formula I in the form of racemates, mixtures of stereoisomers or optically pure stereoisomers
Xi and X 2 are each, independently of one another, a secondary phosphino group;
Ri is a halogen atom or a substituent bound via a C atom, N atom, S atom, Si atom, a P(O) group or a P(S) group to the cyclopentadienyl ring, with the radicals Ri in the case of m > 1 being identical or different;
R 2 is CrC 4 -alkyl or phenyl; m is from 1 to 3 and n is 0 or from 1 to 5.
2. Compounds according to Claim 1 , characterized in that the secondary phosphino groups Xi and X 2 contain two identical or two different hydrocarbon radicals and in that the secondary phosphino groups Xi and X 2 are identical or different.
3. Compounds according to Claim 1, characterized in that Xi and X 2 are identical or different noncyclic sec-phosphino groups selected from the group consisting of -P(Ci-C 6 -alkyl) 2 , -P(C 5 -C 8 -cycloal kyl) 2 , -P(C 7 -Ci 2 -bicycloalkyl) 2 , -P(o-furyl) 2 , -P(C 6 H 5 ) 2 ,
-PP-(Ci-Cβ-alkyl)CβH4]2, -P[3-(Ci-Cβ-alkyl)CβH4]2, -P[4-(Ci-Cβ-alkyl)CβH 4 ]2, -P[2-(Ci-C 6 -alkoxy)C 6 H4] 2j -P[3-(Ci-C 6 -alkoxy)C 6 H4] 2j -P[4-(Ci-C 6 -alkoxy)C 6 H 4 ] 2j -P[2-(trifluoromethyl)C 6 H4] 2j -P[3-(trifluoromethyl)C 6 H4] 2j -P[4-(trifluoromethyl)C 6 H 4 ] 2j -P[3,5-bis(trifluoromethyl)C 6 H 3 ] 2 , -P[3,5-bis(Ci-C 6 -alkyl) 2 C 6 H 3 ] 2 , -P[3,5-bis(Ci-C 6 -alkoxy) 2 C 6 H 3 ] 2 , -P[3,4,5-tris(Ci-C 6 -alkoxy) 2 C 6 H 3 ] 2 and -P[3,5-bis(Ci-C 6 -alkyl) 2 -4-(Ci-C 6 -alkoxy)C 6 H 2 ] 2 , or cyclic phosphine selected from the group consisting of
which are unsubstituted or substituted by one or more substituents selected from among CrC 4 -alkyl, CrC 4 -alkoxy, CiC 4 -alkoxy-CrC 2 -alkyl, phenyl, benzyl, benzyloxy, CrC 4 - alkylidenedioxyl and unsubstituted or phenyl-substituted methylenedioxyl.
4. Compounds according to Claim 1, characterized in that Xi and X 2 are each -P(CH 3 ) 2 , -P(i-C 3 H 7 ) 2> -P(n-C 4 H 9 ) 2j -P(i-C 4 H 9 ) 2j -P(C 6 Hn) 2 , -P(norbomyl) 2j -P(o-furyl) 2j -P(C 6 H 5 ) 2j P[2-(methyl)C 6 H 4 ] 2j P[3-(methyl)C 6 H 4 ] 2j -P[4-(methyl)C 6 H 4 ] 2j -P[2-(methoxy)C 6 H 4 ] 2j -P[3-(methoxy)C 6 H 4 ] 2 , -P[4-(methoxy)C 6 H 4 ] 2 , -P[3-(trifluoromethyl)C 6 H 4 ] 2j -P[4-(trifluoromethyl)C 6 H 4 ] 2j -P[3 J 5-bis(trifluoromethyl)C 6 H 3 ] 2j -P[3,5-bis(methyl)C 6 H 3 ] 2j -P[3,5-bis(methoxy)C 6 H 3 ] 2 , -P[3 J 4 J 5-tri(methoxy)C 6 H 2 ] 2j -P[3,5-bis(methyl) 2 -4-(methoxy)C 6 H 2 ] 2 or a group having one of the formulae
R' is methyl, ethyl, methoxy, ethoxy, phenoxy, benzyloxy, methoxymethyl, ethoxymethyl or benzyloxymethyl and R" has one of the meanings of R'.
5. Compounds according to Claim 1, characterized in that n in formula I is 0.
6. Compounds according to Claim 1, characterized in that a substituent Ri is bound in the 5 position and the substituent is a bulky substituent.
7. Compounds according to Claim 1 , characterized in that the substituents Ri are selected from among Ci-C 4 -alkyl, substituted or unsubstituted phenyl, tri(CrC 4 -alkyl)Si, triphenylsilyl, halogen, -SR 06 , -CH 2 OH, -CHR 06 OH, -CR 06 RO 6 OH, -CH 2 O-R 06 , -CH(O), -CO 2 H, -CO 2 R 06 , where R 06 is a hydrocarbon radical having from 1 to 10 carbon atoms and R' 06 O independently has one of the meanings of R' o6 , and -P(O)(R 03 ) 2 , where R 03 is hydrogen, Ci-C 8 -alkyl, C 5 -C 6 -cycloalkyl, phenyl or benzyl.
8. Compounds according to Claim 1 , characterized in that the compounds of the formula I correspond to racemates, mixtures of stereoisomers or optically pure stereoisomers of the formula Ia
Xi and X 2 are each, independently of one another, a secondary phosphino group; Ri is a halogen atom or a substituent bound via a carbon atom or Si atom to the cyclopentadienyl ring.
9. Compounds according to Claim 8, characterized in that Ri is substituted or unsubstituted linear or branched CrCi 2 -alkyl, substituted or unsubstituted C 3 -Ci 2 -cycloalkyl, substituted or unsubstituted C 3 -C 8 -cycloalkyl-CrC 4 -alkyl, substituted or unsubstituted C 6 -Ci 8 -aryl, substituted or unsubstituted C 7 -Ci 8 -aralkyl, tri(CrC 4 -alkyl)Si-, triphenylsilyl or F, Cl and Br.
10. Complexes of metals selected from the group of transition metals of the Periodic Table of the Elements, preferably from the group Cu, Ag, Au, Ni, Co, Rh, Pd, Ir, Ru and Pt, with compounds of the formula I as ligands.
11. Metal complexes according to Claim 10 which correspond to the formulae III and IV,
A 3 MeL r (III), (A 3 MeL r ) (z+) (E ) z (IV),
where A 3 is one of the compounds of the formula I,
L represents identical or different monodentate, anionic or nonionic ligands, or L represents identical or different bidentate, anionic or nonionic ligands; r is 2, 3 or 4 when L is a monodentate ligand or n is 1 or 2 when L is a bidentate ligand; z is 1, 2 or 3;
Me is a metal selected from the group consisting of Rh, Ir and Ru; with the metal having the oxidation state 0, 1 , 2, 3 or 4;
E " is the anion of an oxo acid or complex acid; and the anionic ligands balance the charge of the oxidation state 1, 2, 3 or 4 of the metal.
12. Metal complexes according to Claim 10 which correspond to the formula VII
[Ru a H b Z c (A 3 ) d L θ ]KE k ) g (S) h (VII) 1
where
Z is Cl, Br or I; A 3 is a compound of the formula I; L represents identical or different ligands; E " is the anion of an oxo acid, mineral acid or complex acid; S is a solvent capable of coordination as ligand; and a is from 1 to 3, b is from 0 to 4, c is from 0 to 6, d is from 1 to 3, e is from 0 to 4, f is from 1 to 3, g is from 1 to 4, h is from 0 to 6 and k is from 1 to 4, with the total charge on the complex being zero.
13. Process for preparing chiral organic compounds by asymmetric addition of hydrogen onto a carbon-carbon or carbon-heteroatom double bond in prochiral organic compounds in the presence of a catalyst, characterized in that the addition reaction is carried out in the presence of catalytic amounts of at least one metal complex according to Claim 10.
14. Use of the metal complexes according to Claim 10 as homogeneous catalysts for the preparation of chiral organic compounds, preferably for the asymmetric addition of hydrogen onto a carbon-carbon or carbon-heteroatom double bond in prochiral organic compounds. |
Ferrocene-diphosphine ligands
The present invention relates to i-sec-phosphinomethyl^-sec-phosphinoferrocenes which are substituted in the cyclopentadienyl ring; processes for preparing them; metal complexes of transition metals with these diphosphines as ligands; and the use of the metal complexes as homogeneous catalysts in asymmetric or symmetric addition reactions and also a process for the preferably asymmetric hydrogenation of prochiral unsaturated organic compounds.
Ferrocene-diphosphines of the formula
It has now surprisingly been found that both the conversion and/or the stereoselectivity and also the configuration of the adduct formed can be influenced when substituents are introduced into the cyclopentadienyl ring. An increase in the conversion, an increase in the optical yields or both effects or else the formation of desired optical isomers is observed. These substituted ligands are highly suitable for optimization if suitable unsubstituted ligands have been identified for a particular reaction. The ligands can be obtained via a novel preparative process.
The invention provides, firstly, compounds of the formula I in the form of racemates, mixtures of stereoisomers or optically pure stereoisomers,
Xi and X 2 are each, independently of one another, a secondary phosphino group; Ri is a halogen atom or a substituent bound via a C atom, N atom, S atom, Si atom, a P(O) group or a P(S) group to the cyclopentadienyl ring, with the radicals Ri in the case of m > 1 being identical or different; R 2 is C r C 4 -alkyl or phenyl; m is from 1 to 3 and n is 0 or from 1 to 5.
For the purposes of illustration, the representational formula of the other enantiomer, which also applies analogously to formulae indicated later, is shown below:
The secondary phosphino groups Xi and X 2 can contain two identical or two different hydrocarbon radicals. In the latter case, the secondary phosphino groups are P-chiral. The secondary phosphino groups Xi and X 2 preferably each contain two identical hydrocarbon radicals. Furthermore, the secondary phosphino groups Xi and X 2 can be identical or different.
The hydrocarbon radicals can be unsubstituted or substituted and/or contain heteroatoms selected from the group consisting of O, S and N. They can contain from 1 to 22, preferably from 1 to 18 and particularly preferably from 1 to 14, carbon atoms. A preferred secondary phosphino group is one which contains two identical or different radicals selected from the group consisting of linear or branched C r Ci 2 -alkyl; unsubstituted or C r C 6 -alkyl- or C r C 6 -
alkoxy-substituted C 5 -Ci 2 -cycloalkyl or C 5 -Ci 2 -cycloalkyl-CH 2 -; phenyl, naphthyl, furyl and benzyl; and phenyl and benzyl substituted by halogen (for example F, Cl and Br), Ci-C 6 -alkyl, CrC 6 -haloalkyl (for example trifluoromethyl), d-C 6 -alkoxy, CrC 6 -haloalkoxy (for example trifluoromethoxy), (C 6 Hs) 3 Si, (Ci-Ci 2 -alkyl) 3 Si, secondary amino or -CO 2 -Ci -C 6 -alkyl (for example -CO 2 CH 3 ).
Examples of alkyl substituents on P, which preferably contain from 1 to 6 carbon atoms, are methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl and the isomers of pentyl and hexyl. Examples of unsubstituted or alkyl-substituted cycloalkyl substituents on P are cyclopentyl, cyclohexyl, methylcyclopentyl and ethylcyclopentyl, dimethylcyclopentyl, methylcyclohexyl and ethylcyclohexyl and dimethylcyclohexyl. Examples of alkyl-, alkoxy-, haloalkyl-, haloalkoxy- and halogen-substituted phenyl and benzyl substituents on P are o-, m- or p- fluorophenyl, o-, m- or p-chlorophenyl, difluorophenyl or dichlorophenyl, pentafluorophenyl, methylphenyl, dimethyl phenyl, trimethylphenyl, ethylphenyl, methylbenzyl, methoxyphenyl, dimethoxyphenyl, trifluoromethylphenyl, bistrifluoromethylphenyl, tristrifluoromethylphenyl, trifluoromethoxyphenyl, bistrifluoromethoxyphenyl and 3,5-dimethyl-4-methoxyphenyl.
Preferred secondary phosphino groups are ones which contain identical radicals selected from the group consisting of CrC 6 -alkyl, unsubstituted cyclopentyl or cyclohexyl and cyclopentyl or cyclohexyl substituted by from 1 to 3 CrC 4 -alkyl or Ci-C 4 -alkoxy groups, benzyl and in particular phenyl which may each be unsubstituted or substituted by from 1 to 3 CrC 4 -alkyl, CrC 4 -alkoxy, F, Cl, Ci-C 4 -fluoroalkyl or Ci-C 4 -fluoroalkoxy groups. The substituent F can also be present four or five times.
The secondary phosphino groups Xi and X 2 preferably correspond, independently of one another, to the formula -PR 3 R 4 , where R 3 and R 4 are each, independently of one another, a hydrocarbon radical having from 1 to 18 carbon atoms which is unsubstituted or substituted by halogen, CrC 6 -alkyl, CrC 6 -haloalkyl, CrC 6 -alkoxy, CrC 6 -haloalkoxy, (C r C 4 -alkyl) 2 - amino, (C 6 H 5 ) 3 Si, (Ci-Ci 2 -alkyl) 3 Si or -CO 2 -Ci -C 6 -alkyl and/or contains heteroatoms O.
R 3 and R 4 are preferably identical radicals selected from the group consisting of linear or branched CrC 6 -alkyl, unsubstituted cyclopentyl or cyclohexyl and cyclopentyl or cyclohexyl substituted by from one to three Ci-C 4 -alkyl or Ci-C 4 -alkoxy groups, furyl, norbomyl, adamantyl, unsubstituted benzyl and benzyl substituted by from one to three C r C 4 -alkyl or Ci-C 4 -alkoxy groups and in particular unsubstituted phenyl and phenyl substituted by from
one to three Ci-C 4 -alkyl, CrC 4 -alkoxy, -NH 2 , -N(Ci-C 6 -alkyl) 2 , OH, F, Cl, C r C 4 -fluoroalkyl or Ci-C 4 -fluoroalkoxy groups.
R 3 and R 4 are particularly preferably identical radicals selected from the group consisting of CrC 6 -alkyl, cyclopentyl, cyclohexyl, furyl and unsubstituted phenyl and phenyl substituted by from one to three d-C 4 -alkyl, C r C 4 -alkoxy and/or C r C 4 -fluoroalkyl groups.
The secondary phosphino groups Xi and X 2 can be cyclic sec-phosphino groups, for example groups of the formulae
which are unsubstituted or substituted by one or more substituents selected from among -OH, Ci-C 8 -alkyl, C 4 -C 8 -cycloalkyl, CrC 6 -alkoxy, Ci-C 4 -alkoxy-CrC 4 -alkyl, phenyl, C r C 4 - alkylphenyl, CrC 4 -alkoxyphenyl, benzyl, CrC 4 -alkylbenzyl, CrC 4 -alkoxybenzyl, benzyloxy, CrC 4 -alkylbenzyloxy, C r C 4 -alkoxybenzyloxy and C r C 4 -alkylidenedioxyl.
The substituents can be bound in one or both α positions relative to the P atom in order to introduce chiral carbon atoms. The substituents in one or both α positions are preferably Ci-C 4 -alkyl or benzyl, for example methyl, ethyl, n- or i-propyl, benzyl or -CH 2 -O-Ci -C 4 -alkyl or -CH 2 -O-C 6 -Ci o-aryl.
Substituents in the β,γ positions can be, for example, C r C 4 -alkyl, C r C 4 -alkoxy, benzyloxy or -0-CH 2 -O-, -0-CH(CrC 4 -alkyl)-0-, -O-C(Ci-C 4 -alkyl) 2 -O- and -O-CH(C 6 -Ci 0 -aryl)-O-. Some examples are methyl, ethyl, methoxy, ethoxy, -O-CH(phenyl)-O-, -O-CH(methyl)-O- and -O-C(methyl) 2 -O-.
An aliphatic 5- or 6-membered ring or benzene can be fused onto two adjacent carbon atoms in the radicals of the above formulae.
Other known and suitable secondary phosphino radicals are those of cyclic and chiral phospholanes having seven carbon atoms in the ring, for example those of the formulae
where the aromatic rings may be substituted by CrC 4 -alkyl, CrC 4 -alkoxy, Ci-C 4 -alkoxy- Ci-C 2 -alkyl, phenyl, benzyl, benzyloxy or Ci-C 4 -alkylidenedioxyl or C r C 4 -alkylenedioxyl (see US 2003/0073868 A1 and WO 02/048161).
Depending on the type of substitution and the number of substituents, the cyclic phosphino radicals can be C-chiral, P-chiral or C- and P-chiral.
The cyclic sec-phosphino group can correspond, for example, to the formulae (only one of the possible diastereomers shown),
In a preferred embodiment, Xi and X 2 in the compounds of the formula I are particularly preferably identical or different noncyclic sec-phosphino selected from the group consisting of -P(Ci-C 6 -alkyl) 2 , -P(C 5 -C 8 -cycloalkyl) 2 , -P(C 7 -Ci 2 -bicycloalkyl) 2 , -P(o-furyl) 2 , -P(C 6 H 5 J 2 , -P[2-(Ci-C 6 -alkyl)C 6 H4] 2j -P[3-(Ci-C 6 -alkyl)C 6 H4] 2j -P[4-(Ci-C 6 -alkyl)C 6 H 4 ] 2j -P[2-(Ci-C 6 -alkoxy)C 6 H 4 ] 2j -P[3-(Ci-C 6 -alkoxy)C 6 H4] 2j -P[4-(Ci-C 6 -alkoxy)C 6 H 4 ] 2j
-P[2-(trifluoromethyl)C 6 H4]2 J -P[3-(trifluoromethyl)C 6 H4]2 J -P[4-(trifluoromethyl)C 6 H4]2 J -P[3 J 5-bis(trifluoromethyl)C 6 H3]2 J -P[3 J 5-bis(Ci-C 6 -alkyl)2C 6 H3]2 J -P[3 J 5-bis(Ci-C 6 -alkoxy)2- C 6 H 3 J 2 , -P[3 J 4 J 5-tris(Ci-C 6 -alkoxy)2C 6 H 3 ]2 J and -P[3 J 5-bis(Ci-C 6 -alkyl)2-4-(Ci-C 6 -alkoxy)C 6 H 2 ]2 or cyclic phosphino selected from the group consisting of
which are unsubstituted or substituted by one or more radicals selected from among C r C 4 - alkyl, d-C 4 -alkoxy, Ci-C 4 -alkoxy-Ci-C 2 -alkyl, phenyl, benzyl, benzyloxy, Ci-C 4 -alkylidene- dioxyl and unsubstituted or phenyl-substituted methylenedioxyl.
Specific examples are -P(CH 3 ) 2 , -P(i-C 3 H 7 ) 2j -P(n-C 4 H 9 ) 2j -P(i-C 4 H 9 ) 2j -P(C 6 Hn) 2 , -P(norbomyl) 2j -P(o-furyl) 2j -P(C 6 H 5 J 2 , P[2-(methyl)C 6 H 4 ] 2j P[3-(methyl)C 6 H 4 ] 2j -P[4-(methyl)C 6 H 4 ] 2j -P[2-(methoxy)C 6 H 4 ] 2j -P[3-(methoxy)C 6 H 4 ] 2j -P[4-(methoxy)C 6 H 4 ] 2j -P[3-(trifluoromethyl)C 6 H 4 ] 2 , -P[4-(trifluoromethyl)C 6 H 4 ] 2 , -P[3,5-bis(trifluoromethyl)C 6 H 3 ] 2 , -P[3 J 5-bis(methyl)C 6 H 3 ] 2j -P[3 J 5-bis(methoxy)C 6 H 3 ] 2j -P[3 J 4 J 5-tri(methoxy)C 6 H 2 ] 2j -P[3,5-bis(methyl) 2 -4-(methoxy)C 6 H 2 ] 2 and radicals of the formulae
R' is methyl, ethyl, methoxy, ethoxy, phenoxy, benzyloxy, methoxy methyl, ethoxymethyl or benzyloxymethyl and R" independently has one of the meanings of R'.
In a preferred embodiment of the compounds of the formula I, R 2 is preferably methyl, n in formula I is particularly preferably 0, or in other words, R 2 is then a hydrogen atom.
The substituent Ri can be present from one to three times, particularly preferably once or twice, in the cyclopentadienyl ring. Preferred positions for a substituent Ri are the 3, 4 and 5 positions. Preferred substitution patterns are the 3 position, the 5 position and the 3 and 5 positions in the case of double substitution.
In a particularly preferred embodiment of the compounds of the formula I, a substituent is bound in the 5 position and this substituent is a bulky substituent such as branched alkyl, substituted linear or branched alkyl, trimethylsilyl or a substituted or unsubstituted cyclic substituent [(hetero)cycloalkyl or (hetero)aryl)].
The substituents Ri can be achiral or contain at least one asymmetric carbon atom. An asymmetric carbon atom is preferably located in the α, β or Y position relative to the carbon atom in the cyclopentadienyl ring to which R 1 is bound.
The substituents Ri can in turn be substituted by one or more substituents, for example from one to three substituents, preferably one or two substituents, for example by halogen (F, Cl or Br, in particular F), -OH, -SH, -CH(O) 1 -CN, -NR OI R O2J -C(O)-O-R 03 , -S(O)-O-R 03 , -S(O) 2 -O-R 03 , -P(OR 03 J 2 , -P(O)(OR 03 J 2 , -C(O)-NR 01 R 02 , -S(O)-NR 01 R 02 , -S(O) 2 -NR 01 R 02 , -0-(O)C-R 04 , -R 01 N-(O)C-R 04 , -R 01 N-S(O)-R 04 , -R 01 N-S(O) 2 -R 04 , C r C 4 -alkyl, C r C 4 -alkoxy, C r C 4 -alkylthio, C 5 -C 6 -cycloalkyl, phenyl, benzyl, phenoxy or benzyloxy, where R 01 and R 02 are each, independently of one another, hydrogen, CrC 4 -alkyl, cyclopentyl, cyclohexyl, phenyl, benzyl or R 01 and R 02 together form tetramethylene, pentamethylene or 3-oxa- pentane-1 ,5-diyl, R 03 is hydrogen, CrC 8 -alkyl, C 5 -C 6 -cycloalkyl, phenyl or benzyl and R 04 is Crds-alkyl, preferably CrC 12 -alkyl, CrC 4 -haloalkyl, CrC 4 -hydroxyalkyl, C 5 -C 8 -cycloalkyl (for example cyclopentyl, cyclohexyl), C 6 -C 10 -aryl (for example phenyl or naphthyl) or C 7 -C 12 - aralkyl (for example benzyl). Two substituents together with the carbon atoms to which they are bound in cyclic substituents also form a saturated or unsaturated, aliphatic or aromatic hydrocarbon ring or heterocyclic ring (fused-on rings and/or bridging rings).
The substituted or unsubstituted substituents R 1 can be, for example, CrC 12 -alkyl, preferably d-Cs-alkyl and particularly preferably C r C 4 -alkyl, C 2 -C 12 -alkenyl, preferably C 2 -C 8 -alkenyl and particularly preferably C 2 -C 4 -alkenyl. Examples are methyl, ethyl, n- or i-propyl, n-, i- or t-butyl and the isomers of pentyl, hexyl, heptyl, octyl, decyl and dodecyl and also vinyl and propenyl.
The substituted or unsubstituted substituents Ri can be, for example, C 3 -Ci 2 -cycloalkyl, preferably C 5 -C 8 -cycloalkyl. Examples are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl and cyclododecyl.
The substituted or unsubstituted substituents Ri can be, for example, C 3 -C 8 -cycloalkyl-C r C 4 - alkyl, preferably Cs-Ce-cycloalkylalkyl. Examples are cyclopentylmethyl, cyclohexylmethyl or cyclohexylethyl and cyclooctyl methyl.
The substituted or unsubstituted substituents Ri can be, for example, C 6 -Ci 8 -aryl and preferably C 6 -Ci 0 -aryl. Examples are phenyl, naphthyl, anthracenyl and phenanthryl.
The substituted or unsubstituted substituents Ri can be, for example, C 7 -Ci 8 -aralkyl and preferably C 7 -Ci 2 -aralkyl, (for example benzyl or 1-phenyleth-2-yl).
The substituted or unsubstituted substituents Ri can be, for example, tri(Ci-C 4 -alkyl)Si or triphenylsilyl. Examples of trialkylsilyl are trimethylsilyl, triethylsilyl-, tri-n-propylsilyl-, tri-n- butylsilyl and dimethyl-t-butylsilyl.
The substituents Ri can be, for example, halogen. Examples are F, Cl and Br.
The substituted or unsubstituted substituents Ri can be, for example, a thio radical or a sulphoxide or sulphone radical of the formulae -SR 05 , -S(O)R 05 and -S(O) 2 R 05 , where R 05 is CrCi 2 -alkyl, preferably CrC 8 -alkyl and particularly preferably Ci-C 4 -alkyl; C 5 -C 8 -cycloalkyl, preferably C 5 -C 6 -cycloalkyl; C 6 -Ci 8 -aryl and preferably C 6 -Ci 0 -aryl; or C 7 -Ci 2 -aralkyl. Examples of these hydrocarbon radicals have been mentioned above.
The substituents Ri can be, for example, -CH(O), -C(O)-Ci -C 4 -alkyl or -C(O)-C 6 -Ci o-aryl.
The substituted or unsubstituted substituents Ri can be, for example, -CO 2 R 03 or -C(O)-NR 0I R 02 radicals, where R θ i, R 02 and R 03 have the meanings given above, including the preferences.
The substituted or unsubstituted substituents Ri can be, for example, -S(O)-O-R 03 , -S(O) 2 -O-R 03 , -S(O)-NR 0I R 02 and -S(O) 2 -N R oi R 02 radicals, where R θ i, R 02 and R 03 have the
meanings given above, including the preferences.
The substituted or unsubstituted substituents Ri can be, for example, -P(ORo 3 ) 2 or -P(0)(ORo 3 ) 2 radicals, where R 03 has the meanings given above, including the preferences.
The substituted or unsubstituted substituents Ri can be, for example, -P(0)(Ro 3 ) 2 or -P(S)(OR 03 ) 2 radicals, where R 03 has the meanings given above, including the preferences.
In a preferred group of substituents R 1 , these are selected from among substituted or unsubstituted CrC 6 -alkyl, substituted or unsubstituted phenyl or naphthyl, tri(Ci-C 4 -alkyl)Si, triphenylsilyl, halogen (in particular F, Cl and Br), -SR 06 , -CH 2 OH, -CHR 06 OH, -CR 06 R' 06 OH, -CH 2 O-R 06 , -CH(O), -CO 2 H, -CO 2 R 06 , where R 06 is a hydrocarbon radical having from 1 to 10 carbon atoms, and -P(O)(R 03 ) 2 , where R 03 is as defined above.
Examples of substituted or unsubstituted substituents Ri are methyl, ethyl, n- and i-propyl, n-, i- and t-butyl, pentyl, hexyl, cyclohexyl, cyclohexyl methyl, dicyclohexylmethyl, phenyl, naphthyl, benzyl, naphthylmethyl, diphenylmethyl, trimethylsilyl, F, Cl, Br, methylthio, methylsulphonyl, methylsulphoxyl, phenylthio, phenylsulphonyl, phenylsulphoxyl, -CH(O), -C(O)OH, -C(O)-OCH 3 , -C(O)-OC 2 H 5 , -C(O)-NH 2 , -C(O)-NHCH 3 , -C(O)-N(CH 3 J 2 , -SO 3 H, -S(O)-OCH 3 ,
-S(O)-OC 2 H 5 , -S(O) 2 -OCH 3 , -S(O) 2 -OC 2 H 5 , -S(O)-NH 2 , -S(O)-NHCH 3 , -S(O)-N(CH 3 J 2 , -S(O)-NH 2 , -S(O) 2 -NHCH 3 , -S(O) 2 -N(CH 3 J 2 , -P(OH) 2 , -PO(OH) 2 , -P(OCH 3 J 2 , -P(OC 2 H 5 ) 2 , -PO(OCH 3 ) 2 , -PO(OC 2 H 5 ) 2 , trifluoromethyl, methylcyclohexyl, methylcyclohexylmethyl, methyl phenyl, dimethylphenyl, methoxyphenyl, dimethoxyphenyl, hydroxymethyl, β-hydroxy- ethyl, γ-hydroxypropyl, C 6 H 5 CH(OH)-, C 6 H 5 CH(OCH 3 )-, CH 3 CH(OH)-, CH 3 CH(OCH 3 )-, C 2 H 5 CH(OH)-, C 2 H 5 CH(OCH 3 )-, (CH 3 J 2 C(OH)-, (CH 3 J 2 C(OCH 3 J-, -CH 2 NH 2 , -CH 2 N(CH 3 J 2 , -CH 2 CH 2 NH 2 , -CH 2 CH 2 N(CH 3 J 2 , methoxymethyl, ethoxymethyl, methoxyethyl, ethoxyethyl, HS-CH 2 -, HS-CH 2 CH 2 -, CH 3 S-CH 2 -, CH 3 S-CH 2 CH 2 -, -CH 2 -C(O)OH, -CH 2 CH 2 -C(O)OH, -CH 2 -C(O)OCH 3 , -CH 2 CH 2 -C(O)OCH 3 , -CH 2 -C(O)NH 2 , -CH 2 CH 2 -C(O)NH 2 , -CH 2 -C(O)- N(CH 3 J 2 , -CH 2 CH 2 -C(O)N(CH 3 J 2 , -CH 2 -SO 3 H, -CH 2 CH 2 -SO 3 H, -CH 2 -SO 3 CH 3 , -CH 2 CH 2 - SO 3 CH 3 , -CH 2 -SO 2 NH 2 , -CH 2 -SO 2 N(CH 3 ) 2 , -CH 2 -PO 3 H 2 , -CH 2 CH 2 -PO 3 H 2 , -CH 2 -PO(OCH 3 ), -CH 2 CH 2 -PO(OCH 3 ) 2 , -C 6 H 4 -C(O)OH, -C 6 H 4 -C(O)OCH 3 , -C 6 H 4 -S(O) 2 OH, -C 6 H 4 -S(O) 2 OCH 3 , -CH 2 -O-C(O)CH 3 , -CH 2 CH 2 -O-C(O)CH 3 , -CH 2 -NH-C(O)CH 3 , -CH 2 CH 2 -NH-C(O)CH 3 , -CH 2 -O-S(O) 2 CH 3 , -CH 2 CH 2 -O-S(O) 2 CH 3 , -CH 2 -NH-S(O) 2 CH 3 , -CH 2 CH 2 -NH-S(O) 2 CH 3 , -P(O)(CrC 8 -alkyl) 2 , -P(S)(CrC 8 -alkyl) 2 , -P(O)(C 6 -C 10 -aryl) 2 , -P(S)(C 6 -C 10 -aryl) 2 , -C(O)-C 1 -C 8 -
alkyl and -C(O)-C 6 -Ci o-aryl.
Preferred compounds of the formula I correspond to racemates, mixtures of stereoisomers or optically pure stereoisomers of the formula Ia
Xi and X 2 are each, independently of one another, a secondary phosphino group; Ri is a halogen atom or a substituent bound via a carbon atom or Si atom to the cyclopentadienyl ring.
For the purposes of illustration, the formula Ib of the other enantiomer will be given:
In the compounds of the formula Ia, Ri is preferably substituted or unsubstituted, linear or branched
The compounds of the formula I can be prepared by various methods, depending on the position in which substituents are to be introduced. The ortho position relative to the group Xi in the cyclopentadienyl group (hereinafter referred to as cp for short) is the 3 position. The ortho position relative to the group -CH 2 X 2 in the cp group is the 5 position. The 4 position is located between the 3 and 5 positions.
Central precursors are compounds of the formula Il which can be selectively metallated in one of the ortho positions and then be modified further,
A 1 is an open-chain or cyclic, achiral sec-amino or a chiral sec-amino in which at least one carbon atom is substituted by di(Ci-C 4 -alkyl)amino or CrC 4 -alkoxy, preferably in the α, β or Y positions relative to the N atom. Some of the compounds of the formula Il are known [see I. Fleischer et al. in Coll. Czech. Chem. Comm., 69(2), (2004), pages 330 to 338 and W. Weissensteiner et al. In J. Org. Chem., 66, (2001), pages 8912 to 8919] or can be prepared by methods analogous to known methods.
An open-chain or cyclic sec-amino group A 1 can correspond to the formula R 5 R 6 N-, where R 5 and R 6 are each, independently of one another, CrC 12 -alkyl and preferably CrC 6 -alkyl, C 3 -C 8 -CyClOaI kyl and preferably C 5 -C 6 -cycloalkyl, or together with the N atom form a 3- to 8- membered and preferably 5- to 8-membered N-heterocyclic ring, and at least one of R 5 and R 6 and/or the heterocyclic ring contain an O- or N-containing substituent when A 1 is chiral sec-amino.
Examples of alkyl, which is preferably linear, are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl. Examples of cycloalkyl are cyclopentyl, cyclohexyl and cyclooctyl. Examples of cycloalkyl are in particular cyclopentyl and cyclohexyl. R 5 and R 6 together are preferably tetramethylene, pentamethylene, 3-oxapentylene or 3-(C r C 4 -alkyl)-N-pentylene when the sec-amino forms an N-heterocylic ring. Suitable substituents are, for example, CrC 4 -alkoxy, C 1 -C 4 -alkoxy methyl, C r C 4 -alkoxyethyl, (CrC 4 -alkyl) 2 N-, (CrC 4 -alkyl) 2 N-methyl and (C 1 -C 4 - alkyl) 2 N-ethyl. The substituents are located, for example, in the Y position and preferably the α or β positions relative to the N atom of the sec-amino group. R 5 and R 6 can additionally be substituted by CrC 4 -alkyl, C 5 -C 6 -cycloalkyl, phenyl or benzyl.
In a preferred embodiment, R 5 and R 6 are each methyl, ethyl, cyclohexyl or R 5 and R 6
together are tetramethylene, pentamethylene or 3-oxapentylene, which are each substituted by Ci-C 4 -alkoxy, CrC 4 -alkoxymethyl, CrC 4 -alkoxyethyl, (Ci-C 4 -alkyl) 2 N-, (Ci-C 4 -alkyl) 2 N-methyl and (CrC 4 -alkyl) 2 N-ethyl and, if desired, additionally by CrC 4 -alkyl, C 5 -C 6 -cycloalkyl, phenyl or benzyl.
Particularly preferred examples Of A 1 are sec-amino radicals of the formulae
where S is CrC 4 -alkoxy, d-C 4 -alkoxy methyl, CrC 4 -alkoxyethyl, (Ci-C 4 -alkyl) 2 N-, (C r C 4 - alkyl) 2 N-methyl or (CrC 4 -alkyl) 2 N-ethyl, where the "*"s represent asymmetric centres.
The possible methods of preparation including all substitution patterns for the compounds of the formula I are indicated in the two reaction schemes 1 and 2 below.
Scheme 1 : Introduction of radicals in 4 and 5 positions <&r — A i
Fe
V \ d)
Scheme 2: Introduction of radicals in 3, 4 and 5 positions
Instead of the bromides, it is also possible to use the iodides.
Ri' and Ri" in the above formulae have, independently of one another, the same meanings
Step a): Introduction of substituents in the ortho position relative to the A 1 CH 2 - group Metallation is firstly carried out by means of a metallating reagent such as alkyllithium and the metallated product is subsequently reacted with an electrophilic compound.
Step b): Replacement of Br or I by H or a substituent
After metallation by means of, for example, alkyllithium, the metallated product is reacted either with water (introduction of H) or an electrophilic compound. Catalytic methods of introducing radicals Ri, for example Suzuki coupling and Heck reactions, are also known.
Step c): Introduction of a substituent in the ortho position relative to a halogen (F, Cl, Br) In a further process step, the ortho position relative to the halogen is selectively lithiated by
means of Li amides and the desired substituents are then introduced in a second process step by reaction with appropriate electrophiles.
Step d): Introduction of Xi in the ortho position relative to the A 1 CH 2 - group
Metallation is firstly carried out by means of metallation reagents such as alkyllithium and the lithiated product is subsequently reacted with a halogen X 1 .
Step e): Replacement Of A 1 by X 2
The group A 1 is replaced in a manner known per se using a secondary phosphine (preferably of the formula R 3 R 4 PH).
Step f): Replacement of Br or I by X 1
After metallation by means of, for example, alkyllithium, the metallated product is reacted with a halogen X 1 .
Depending on the reaction sequence, the substituent introduced has to be inert towards metallation reagents and/or under the reaction conditions in the replacement of A 1 by a secondary phosphino group. Another possibility is the known use of protective groups which can be split off for radicals which are sensitive to reaction conditions selected.
The individual process steps with the exception of step c) are known and are widely described in the literature.
The metallation of ferrocenes involves known reactions which have been described, for example, by W. Weissensteiner et al., J. Org. Chem., 66 (2001) 8912-9, W. Weissensteiner et al., Synthesis 8 (1999), pages 1354-1362, T. Hayashi et al., Bull. Chem. Soc. Jpn. 53 (1980), pages 1138 to 1151 or in Jonathan Clayden Organolithiums: Selectivity for Synthesis (Tetrahedron Organic Chemistry Series), Pergamon Press (2002). The alkyl in the alkyllithium can, for example, contain from 1 to 4 carbon atoms. Use is frequently made of methyllithium and butyllithium. Magnesium Grignard compounds are preferably ones of the formula (CrC 4 -alkyl)MgX 0 , where X 0 is Cl, Br or I.
The reaction is advantageously carried out at low temperatures, for example from 20 to -100 0 C, preferably from 0 to -80 0 C. The reaction time is from about 2 to 20 hours. The reaction is advantageously carried out under an inert protective gas, for example nitrogen or
noble gases such as argon.
The reaction is advantageously carried out in the presence of inert solvents. Such solvents can be used either alone or as a combination of at least two solvents. Examples of solvents are aliphatic, cycloaliphatic and aromatic hydrocarbons and also open-chain or cyclic ethers. Specific examples are petroleum ether, pentane, hexane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, diethyl ether, dibutyl ether, tert-butyl methyl ether, ethylene glycol dimethyl or diethyl ether, tetrahydrofuran and dioxane.
The introduction of halogens is generally carried out directly after the metallation in the same reaction mixture, with similar reaction conditions as in the metallation being maintained. From 1 to 1.4 equivalents of a halogenated reagent can preferably be used. Halogenated reagents are, for example, halogens (Cl 2 , Br 2 , I 2 ), interhalogens (Cl-Br, Cl-I) and aliphatic, per- halogenated hydrocarbons (CI 3 C-CCI 3 or BrF 2 C-CF 2 Br) for introducing Cl, Br or I; or N-fluorobis(phenyl)sulphonylamine for introducing fluorine.
The metallation in the ortho position relative to the A 1 CH 2 - group and the introduction of electrophiles proceed regioselectively and the intermediates are obtained in high yields. The reaction is also stereoselective in the presence of a chiral group A 1 CH 2 -. Furthermore, if necessary at all, it is possible for optical isomers to be separated at this stage, for example by chromatography using chiral columns.
In process stage c), the ferrocene skeleton is once again metallated regioselectively in the ortho position relative to the halogen atom in the same cyclopentadienyl ring, with metal amides being sufficient to replace the acidic H atom in the ortho position relative to the halogen atom. At least from 1 to 5 equivalents of an aliphatic lithium sec-amide or a CIMg, BrMg or IMg sec-amide are used per CH group in the cyclopentadienyl ring of the ferrocene.
Aliphatic lithium sec-amide or halogenMg sec-amide can be derived from secondary amines containing from 2 to 18, preferably from 2 to 12 and particularly preferably from 2 to 10, carbon atoms. The aliphatic radicals bound to the N atom can be alkyl, cycloalkyl or cycloalkylalkyl, or can be N-heterocyclic rings having from 4 to 12, preferably from 5 to 7, carbon atoms. Examples of radicals bound to the N atom are methyl, ethyl, n- and i-propyl, n-butyl, pentyl, hexyl, cyclopentyl, cyclohexyl and cyclohexyl methyl. Examples of N-heterocyclic rings are pyrrolidine, piperidine, morpholine, M-methylpiperazine, 2,2,6,6-tetramethyl-
piperidine and azanorbornane. In a preferred embodiment, the amides correspond to the formulae Li-N(C 3 -C 4 -alkyl) 2 or X 2 Mg-N(C 3 -C 4 -alkyl) 2j where alkyl is, in particular, i-propyl. In another preferred embodiment, the amides correspond to Li(2,2,6,6-tetramethylpiperidine).
Examples of reactive electrophilic compounds for forming radicals Ri are: halogens (Cl 2 , Br 2 , 1 2 ), interhalogens (Cl-Br, Cl-I) and aliphatic, perhalogenated hydrocarbons (CI 3 C-CCI 3 or BrF 2 C-CF 2 Br, N-fluorobis(phenyl)sulphonylamine) for introducing F, Cl, Br or I; CO 2 for introducing the carboxyl group -CO 2 H; chlorocarbonates or bromocarbonates [CI-C(O)-OR] for introducing a carboxylate group, where R is a hydrocarbon radical (alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heteroarγl, heteroaralkyl) which has from 1 to 18, preferably from 1 to 12 and particularly preferably from 1 to 8, carbon atoms and is unsubstituted or substituted by inert substituents such as sec- phosphino, di(CrC 8 -alkyl) 2 N-, -C(O)-OCi -C 8 -alkyl or -OC r C 8 -alkyl (inert substituents also include reactive groups such as Cl, Br or I when groups which are more reactive towards a metal or a metal group, for example -CHO, are at the same time present in compounds of the formula I or when Cl and Br, Cl and I or Br and I are simultaneously present in bound form in a preferably aromatic hydrocarbon radical); di(Ci-C 4 -alkyl)formamides, for example dimethylformamide or diethylformamide, for introducing the group -CH(O); di(Ci-C 4 -alkyl)carboxamides for introducing a -C(O)-R group; aldehydes which may be unsubstituted or substituted by sec-phosphino in the group R for introducing a -CH(OH)-R group or paraformaldehyde for introducing the -CH 2 OH group; symmetrical or unsymmetrical ketones which may be unsubstituted or substituted by sec- phosphino in the R or R a group for introducing a -C(OH)RR 3 group, where R a independently has one of the meanings of R or R and R a together form a cycloaliphatic ring having from 3 to 8 ring members; epoxides for introducing a -C-C-OH group in which the C atoms may be substituted by H or
R;
Eschenmoser salt of the formula (CH 3 ) 2 N + =CH 2 xl ~ ; imines R-CH=N-R 3 for introducing the group -CH(R)-NHR 3 , where R 3 independently has one of the meanings of R or R and R 3 together form a cycloaliphatic ring having from 3 to 8 ring members; R and R 3 are not simultaneously hydrogen; imines R-C(R b )=N-R 3 for introducing the group -C(R)(R b )-NHR 3 , where R 3 independently has one of the meanings of R or R and R' together form a cycloaliphatic ring having from 3 to 8 ring members, R b independently has one of the meanings of R or R and R b together form a
cycloaliphatic ring having from 3 to 8 ring members; hydrocarbon monohal ides and heterohydrocarbon monohalides, in particular chlorides, bromides and iodides, for introducing hydrocarbon and heterohydrocarbon radicals (for example d-ds-alky!, C 6 -Ci 4 -aryl, C 7 -Ci 4 -aralkyl); halohydrocarbons and haloheterohydrocarbons having halogen atoms of differing reactivity, in particular combinations of chlorine with bromine or iodine, bromine with iodine or two bromine or iodine atoms, for introducing hydrocarbon and heterohydrocarbon radicals (for example CrCi 8 -alkyl, C 6 -Ci 4 -aryl, C 7 -Ci 4 -aralkyl); arylboronic acids for introducing aryl and heteroaryl radicals; alkenyl halides, in particular chlorides, bromides and iodides, for introducing alkenyl groups such as allyl and vinyl; tri(Ci-C 8 -alkyl)silyl halides (chlorides, bromides) for introducing the tri(CrC 8 -alkyl)-Si- group, triphenylsilyl halides for introducing the triphenylsilyl group; phosphoric ester monohalides (chlorides, bromides) for introducing phosphonic ester groups such as (CH 3 O) 2 (O)P-, (C 2 H 5 O)(O)P-, (cyclohexylO) 2 (O)P-, (ethylenedioxyl)(O)P-; phosphoric thioester monohalides (chlorides, bromides) for introducing phosphonic thioester groups such as (CH 3 O) 2 (S)P-, (C 2 H 5 O)(S)P-, (cyclohexylO) 2 (S)P-, (ethylenedioxyl)(S)P-; organic disulphides R-SS-R for introducing the -SR group; and sulphur (S 8 ) for introducing the -SH group.
Organic radicals in the electrophiles can be substituted as described above.
The metal complexes of the invention are homogeneous catalysts or catalyst precursors which can be activated under the reaction conditions which can be used for asymmetric addition reactions onto prochiral, unsaturated, organic compounds, see E. Jacobsen, A. Pfaltz, H. Yamamoto (Eds.), Comprehensive Asymmetric Catalysis I to III, Springer Verlag, Berlin, 1999, and B. Cornils et al., in Applied Homogeneous Catalysis with Organometallic Compounds, Volume 1 , Second Edition, Wiley VCH-Verlag (2002).
The compounds of the formula I according to the invention are ligands for complexes of metals selected from among transition metals in the Periodic Table, preferably the group of TM8 metals, particularly preferably from the group consisting of Ru, Rh and Ir, which are excellent catalysts or catalyst precursors for asymmetric syntheses, for example the asymmetric hydrogenation of prochiral, unsaturated, organic compounds. If prochiral unsaturated organic compounds are used, a very high excess of optical isomers can be induced in the synthesis of organic compounds and a high chemical conversion can be
achieved in short reaction times. The achievable enantioselectivites and catalyst activities are excellent and in an asymmetric hydrogenation are considerably higher than in the case of the known unsubstituted ligands mentioned at the outset. Furthermore, such ligands can also be used in other asymmetric addition or cyclization reactions.
The invention further provides complexes of metals selected from among the group of transition metals of the Periodic Table with one of the compounds of the formula I as ligand.
Possible metals are, for example, Cu, Ag, Au, Ni, Co, Rh, Pd, Ir, Ru and Pt. Preferred metals are rhodium and iridium and also ruthenium, platinum, palladium and copper.
Particularly preferred metals are ruthenium, rhodium and iridium.
The metal complexes can, depending on the oxidation number and coordination number of the metal atom, contain further ligands and/or anions. They can also be cationic metal complexes. Such analogous metal complexes and their preparation have been widely described in the literature.
The metal complexes can, for example, correspond to the general formulae III and IV
A 3 MeL r (III), (A 3 MeL r ) (z+) (E ) z (IV),
where A 3 is one of the compounds of the formula I,
L represents identical or different monodentate, anionic or nonionic ligands, or L represents identical or different bidentate, anionic or nonionic ligands; r is 2, 3 or 4 when L is a monodentate ligand or n is 1 or 2 when L is a bidentate ligand; z is 1, 2 or 3;
Me is a metal selected from the group consisting of Rh, Ir and Ru; with the metal having the oxidation state 0, 1 , 2, 3 or 4;
E " is the anion of an oxo acid or complex acid; and the anionic ligands balance the charge of the oxidation state 1, 2, 3 or 4 of the metal.
The above-described preferences and embodiments apply to the compounds of the formula I.
Monodentate nonionic ligands can, for example, be selected from the group consisting of
olefins (for example ethylene, propylene), solvating solvents (nitriles, linear or cyclic ethers, unalkylated or N-alkylated amides and lactams, amines, phosphines, alcohols, carboxylic esters, sulphonic esters), nitrogen monoxide and carbon monoxide.
Suitable polydentate anionic ligands are, for example, allyls (allyl, 2-methallyl), cyclopentadienyl or deprotonated 1,3-diketo compounds such as acetylacetonate.
Monodentate anionic ligands can, for example, be selected from the group consisting of halide (F, Cl, Br, I), pseudohalide (cyanide, cyanate, isocyanate) and anions of carboxylic acids, sulphonic acids and phosphonic acids (carbonate, formate, acetate, propionate, methylsufonate, trifluoromethylsulphonate, phenylsufonate, tosylate).
Bidentate nonionic ligands can, for example, be selected from the group consisting of linear or cyclic diolefins (for example hexadiene, cyclooctadiene, norbornadiene), dinitriles (malononitrile), unalkylated or N-alkylated carboxylic diamides, diamines, diphosphines, diols, dicarboxylic diesters and disulphonic diesters.
Bidentate anionic ligands can, for example, be selected from the group consisting of anions of dicarboxylic acids, disulphonic acids and diphosphonic acids (for example of oxalic acid, malonic acid, succinic acid, maleic acid, methylenedisulphonic acid and methylenediphosphonic acid).
Preferred metal complexes also include those in which E is -Cl " , -Br " , -I " , CIO 4 " , CF 3 SO 3 " , CH 3 SO 3 " , HSO 4 " , (CF 3 SO 2 J 2 N " , (CF 3 SO 2 ) 3 C " , tetraaryl borates such as B(phenyl) 4 " , B[bis(3,5-trifluoromethyl)phenyl] 4 " , B[bis(3,5-dimethyl)phenyl] 4 " , B(C 6 F 5 ) 4 " and B(4-methylphenyl) 4 " , BF 4 " , PF 6 " , SbCI 6 " , AsF 6 " or SbF 6 " .
Particularly preferred metal complexes which are particularly suitable for hydrogenations correspond to the formulae V and Vl,
[A 3 MeY 1 Z] (V), [A 3 MeY 1 J + E 1 " (Vl),
where
A 3 is one of the compounds of the formula I;
Me is rhodium or iridium;
Y 1 is two olefins or a diene;
Z is Cl, Br or I; and
E 1 " is the anion of an oxo acid or complex acid.
The above-described embodiments and preferences apply to the compounds of the formula I.
Olefins Yi can be C 2 -Ci 2 -olefins, preferably C 2 -C 6 -olefins and particularly preferably C 2 -C 4 - olefins. Examples are propene, 1-butene and in particular ethylene. The diene can have from 5 to 12, preferably from 5 to 8, carbon atoms and can be an open-chain, cyclic or polycyclic diene. The two olefin groups of the diene are preferably connected by one or two CH 2 groups. Examples are 1,4-pentadiene, cyclopentadiene, 1,5-hexadiene, 1,4-cyclohexadiene, 1 ,4- or 1,5-heptadiene, 1,4- or 1,5-cycloheptadiene, 1,4- or 1,5-octadiene, 1,4- or 1,5-cyclo- octadiene and norbomadiene. Y is preferably two ethylenes or 1,5-hexadiene, 1,5-cyclo- octadiene or norbomadiene.
In the formula V, Z is preferably Cl or Br. Examples of Ei are BF 4 " , CIO 4 " , CF 3 SO 3 " , CH 3 SO 3 " , HSO 4 " , B(phenyl) 4 " , B[bis(3,5-trifluoromethyl)phenyl] 4 " , PF 6 " , SbCI 6 " , AsF 6 " or SbF 6 " .
The metal complexes of the invention are prepared by methods known in the literature (see also US-A-5,371 ,256, US-A-5,446,844, US-A-5,583,241 and E. Jacobsen, A. Pfaltz, H. Yamamoto (Eds.), Comprehensive Asymmetric Catalysis I to III, Springer Verlag, Berlin, 1999, and references cited therein).
Ruthenium complexes can, for example, correspond to the formula VII,
[Ru a H b Z c (A 3 ) d L θ ]KE k ) g (S) h (VII),
where
Z is Cl, Br or I; A 3 is a compound of the formula I; L represents identical or different ligands; E " is the anion of an oxo acid, mineral acid or complex acid; S is a solvent capable of coordination as ligand; and a is from 1 to 3, b is from O to 4, c is from O to 6, d is from 1 to 3, e is from O to 4, f is from 1 to 3, g is from 1 to 4, h is from O to 6 and k is from 1 to 4, with the total charge on the complex being zero.
The preferences indicated above for Z, A 3 , L and E " apply to the compounds of the formula VII. The ligands L can additionally be arenes or heteroarenes (for example benzene,
naphthalene, methyl benzene, xylene, cumene, 1 ,3,5-mesitylene, pyridine, biphenyl, pyrrole, benzimidazole or cyclopentadienyl) and metal salts having a Lewis acid function (for example ZnCI 2 , AICI 3 , TiCI 4 and SnCI 4 ). The solvent ligands can be, for example, alcohols, amines, acid amides, lactams and sulphones.
Complexes of this type are described in the literature mentioned below and the references cited therein:
D. J. Ager, S. A. Laneman, Tetrahedron: Asymmetry, 8, 1997, 3327 - 3355; T. Ohkuma, R. Noyori in Comprehensive Asymmetric Catalysis (E.N. Jacobsen, A. Pfaltz, H. Yamamoto, Eds.), Springer, Berlin, 1999, 199-246;
J. M. Brown in Comprehensive Asymmetric Catalysis (E.N. Jacobsen, A. Pfaltz, H. Yamamoto, Eds.), Springer, Berlin, 1999, 122 - 182;
T. Ohkuma, M. Kitamura, R. Noyori in Catalytic Asymmetric Synthesis, 2nd Edition (I. Ojima, Ed.), Wiley-VCH New York, 2000, 1 - 110; N. Zanetti, et al. Organometallics 15, 1996, 860.
The metal complexes of the invention are homogeneous catalysts or catalyst precursors which can be activated under the reaction conditions, which can be used for asymmetric addition reactions onto prochiral, unsaturated, organic compounds.
The metal complexes can, for example, be used for asymmetric hydrogenation (addition of hydrogen) of prochiral compounds having carbon-carbon or carbon-heteroatom double bonds. Such hydrogenations using soluble homogeneous metal complexes are described, for example, in Pure and Appl. Chem., Vol. 68, No. 1 , pages 131-138 (1996). Preferred unsaturated compounds to be hydrogenated contain the groups C=C, C=N and/or C=O. According to the invention, metal complexes of ruthenium, rhodium and iridium are preferably used for the hydrogenation.
The invention further provides for the use of the metal complexes of the invention as homogeneous catalysts for preparing chiral organic compounds, preferably for the asymmetric addition of hydrogen onto a carbon-carbon or carbon-heteroatom double bond in prochiral organic compounds.
The invention also provides a process for preparing chiral organic compounds by asymmetric addition of hydrogen onto a carbon-carbon or carbon-heteroatom double bond in prochiral
organic compounds in the presence of a catalyst, which is characterized in that the addition reaction is carried out in the presence of catalytic amounts of at least one metal complex according to the invention.
Preferred prochiral, unsaturated compounds to be hydrogenated can contain one or more, identical or different groups C=C, C=N and/or C=O in open-chain or cyclic organic compounds, with the groups C=C, C=N and/or C=O being able to be part of a ring system or being exocyclic groups. The prochiral unsaturated compounds can be alkenes, cycloalkenes, heterocycloalkenes or open-chain or cyclic ketones, α,β-diketones, α- or β-ketocarboxylic acids or their α,β-keto acetals or ketals, esters and amides, ketimines and kethydrazones.
Some examples of unsaturated organic compounds are acetophenone, 4-methoxyaceto- phenone, 4-trifluoromethylacetophenone, 4-nitroacetophenone, 2-chloroacetophenone, corresponding unsubstituted or N-substituted acetophenonebenzylimines, unsubstituted or substituted benzocyclohexanone or benzocyclopentanone and corresponding imines, imines from the group consisting of unsubstituted or substituted tetrahydroquinoline, tetrahydro- pyridine and dihydropyrrole, and unsaturated carboxylic acids, esters, amides and salts, for example α- and, if appropriate, β-substituted acrylic acids or crotonic acids. Preferred carboxylic acids are those of the formula
Rioi-CH=C(Rio 2 )-C(0)OH
and also their salts, esters and amides, where R 101 is CrC 6 -alkyl, unsubstituted C 3 -C 8 - cycloalkyl or C 3 -C 8 -cycloalkyl substituted by from 1 to 4 CrC 6 -alkyl, d-C 6 -alkoxy or CrC 6 - alkoxy-C r C 4 -alkoxy groups, or unsubstituted C 6 -Ci 0 -aryl, preferably phenyl, or C 6 -Ci 0 -aryl, preferably phenyl, substituted by from 1 to 4 CrC 6 -alkyl, CrC 6 -alkoxy or Ci-C 6 -alkoxy-CrC 4 - alkoxy groups, and R 102 is linear or branched C r C 6 -alkyl (for example isopropyl) or cyclo- pentyl, cyclohexyl, phenyl or protected amino (for example acetylamino) which may in each case be unsubstituted or be substituted as defined above.
The process of the invention can be carried out at low or elevated temperatures, for example temperatures of from -20 to 150°C, preferably from -10 to 100°C and particularly preferably from 10 to 8O 0 C. The optical yields are generally better at relatively low temperature than at higher temperatures.
The process of the invention can be carried out at atmospheric pressure or superatmos-
pheric pressure. The pressure can be, for example, from 10 5 to 2x10 7 Pa (pascal). Hydrogenations can be carried out at atmospheric pressure or under superatmospheric pressure.
Catalysts are preferably used in amounts of from 0.0001 to 10 mol%, particularly preferably from 0.001 to 10 mol% and in particular from 0.01 to 5 mol%, based on the compound to be hydrogenated.
The preparation of the ligands and catalysts and the hydrogenation can be carried out without solvents or in the presence of an inert solvent, with one solvent or mixtures of solvents being able to be used. Suitable solvents are, for example, aliphatic, cycloaliphatic and aromatic hydrocarbons (pentane, hexane, petroleum ether, cyclohexane, methyl- cyclohexane, benzene, toluene, xylene), aliphatic halogenated hydrocarbons (methylene chloride, chloroform, dichloroethane and tetrachloroethane), nitriles (acetonitrile, propionitrile, benzonitrile), ethers (diethyl ether, dibutyl ether, t-butyl methyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane, diethylene glycol monomethyl or monoethyl ether), ketones (acetone, methyl iso butyl ketone), carboxylic esters and lactones (ethyl or methyl acetate, valerolactone), N-substituted lactams (N-methylpyrrolidone), carboxamides (dimethylamide, dimethylformamide), acyclic ureas (dimethylimidazoline) and sulphoxides and sulphones (dimethyl sulphoxide, dimethyl sulphone, tetramethylene sulphoxide, tetramethylene sulphone) and alcohols (methanol, ethanol, propanol, butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether) and water. The solvents can be used either alone or as a mixture of at least two solvents.
The reaction can be carried out in the presence of cocatalysts, for example quaternary ammonium halides (tetrabutylammonium iodide) and/or in the presence of protic acids, for example mineral acids (see, for example, US-A-5,371 ,256, US-A-5,446,844 and US-A-5,583,241 and EP-A-O 691 949). The presence of fluorinated alcohols such as 1 ,1 ,1-trifluoroethanol can likewise aid the catalytic reaction.
The metal complexes used as catalysts can be added as separately prepared, isolated compounds or can also be formed in situ prior to the reaction and then be mixed with the substrate to be hydrogenated. It can be advantageous to add additional ligands in the reaction using isolated metal complexes or to use an excess of the ligands in the in-situ
preparation. The excess can be, for example, from 1 to 6 mol, preferably from 1 to 2 mol, based on the metal compound used for the preparation.
The process of the invention is generally carried out by initially charging the catalyst and then adding the substrate, if desired reaction auxiliaries and the compound to be added on and subsequently starting the reaction. Gaseous compounds to be added on, for example hydrogen or ammonia, are preferably introduced under pressure. The process can be carried out continuously or batchwise in various types of reactor.
The chiral organic compounds which can be prepared according to the invention are active substances or intermediates for the preparation of such substances, in particular in the field of production of flavours and fragrances, pharmaceuticals and agrochemicals.
The following examples illustrate the invention.
A) Preparation of substituted ferrocene-diphosphines
Abbreviations: Me is methyl, Et is ethyl, Bu is butyl, Ph is phenyl, Cy is cyclohexyl, XyI is 3,5-dimethylphen-1-yl; PE is petroleum ether; Et 2 O is diethyl ether; nbd = norbomadiene; COD is cyclooctadiene.
Example A1 : Preparation of (S p )-1-diphenylphosphino-2-dicyclohexylphosphinomethyl- 3-methylferrocene (A1)
a) Preparation of compound (1)
The compound (1) is described in the literature: I. Fleischer, S. Toma, Coll. Czech. Chem. Comm., 69(2), (2004) 330-338.
b) Preparation of (1f?,2S,S p )-λ/-(1-diphenylphosphino-3-methylferrocen-2-ylmethyl)-N-me thyl-
1-methoxy-1-phenylprop-2-ylamine (2)
6.6 ml (8.5 mmol) of s-butyllithium (1.3 M in cyclohexane) are added dropwise by means of a syringe to a degassed solution of 2.78 g (7.1 mmol) of compound (1) in 80 ml of absolute diethyl ether. The reaction mixture is stirred at -78°C for 1 hour and at -30 0 C for 40 minutes. 1.92 ml (10.6 mmol) of CIPPh 2 are subsequently added. After 1 hour at -30°C, the mixture is stirred for another 16 hours at room temperature. The reaction is stopped by addition of 1 M aqueous NaOH solution. The aqueous phase is extracted with diethyl ether, and the combined organic phases are then washed with saturated aqueous NaCI solution and dried over MgSO 4 . The solvent is removed under reduced pressure and the crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O (10:1)]. This gives the compound (2) as a yellow solid (3 g, 5.2 mmol, 73% of theory).
1 H NMR (400.1 MHz): δ 0.77 (d, 3H), 1.97 (s, 3H), 2.00 (s, 3H), 2.73 (dq, 1H), 2.94 (s, 3H), 3.49 (d, 1 H), 3.89 (dd, 1 H), 3.70 (d, 1 H), 3.75 (d, 1H), 3.85 (s, 5H), 4.22 (d, 1 H), 7.09-7.20 (m, 5H), 7.20-7.26 (m, 3H), 7.26-7.33 (m, 2H), 7.34-7.43 (m, 3H), 7.54-7.64 (m, 2H). 31 P-NMR (162.0 MHz): δ -23.0 (s).
c) Preparation of the title compound A1
0.43 ml (2.09 mmol) of HPCy 2 is added dropwise by means of a syringe to a degassed solution of 1 g (1.74 mmol) of compound (2) in 12 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100 0 C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography (AI 2 O 3 , PE:Et 2 O:Et 3 N (40:1 :0.4)). This gives the title compound A1 as a yellow solid (0.85 g, 14.3 mmol, 82% of theory). 1 H NMR (400.1 MHz): δ . 0-.&SB6 (m, 1H), 0.79-1.33 (m, 12H), 1.35-1.89 (m, 11H), 2.12 (s, 3H), 2.65 (dd, 1H), 3.07 (dt, 1 H), 3.72 (s, 5H), 3.80 (d, 1H), 4.26 (d, 1 H), 7.12-7.23 (m, 5H), 7.33-7.40 (m, 3H), 7.55-7.63 (m, 2H). 31 P-NMR (162.0 MHz): δ -22.6 (d), 3.5 (d).
Example A2: Preparation of (S p )-1-diphenylphosphino-2-di-f-butylphosphinomethyl- 3-methylferrocene (A2)
0.48 ml (2.61 mmol) of HP(f-Bu) 2 is added dropwise by means of a syringe to a degassed solution of 1 g (1.74 mmol) of compound (2) in 12 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100 0 C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with
saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O:Et 3 N (40:1 :0.1)]. This gives the desired product as a yellow solid (0.71 g, 13.1 mmol, 75% of theory). 1 H NMR (400.1 MHz): δ 0.96 (d, 9H), 1.06 (d, 9H), 2.22 (s, 3H), 2.88 (d, 1 H 1 ), 3.24 (dt, 1H), 3.69 (s, 5H), 3.90 (d, 1 H), 4.24 (d, 1H), 7.15-7.21 (m, 3H), 7.24-7.31 (m, 2H), 7.33-7.39 (m, 3H), 7.60-7.68 (m, 2H). 31 P-NMR (162.0 MHz): δ -23.7 (d), 30.2 (d).
Example A3: Preparation of (S p )-1-diphenylphosphino-2-bis(3,5-dimethylphenyl)phosphino- methyl-3-methylferrocene (A3)
2.89 ml of a solution of HP[3,5-(CH 3 ) 2 C 6 H 3 ] 2 (0.7 g, 2.90 mmol) in toluene (24.3%) are added dropwise by means of a syringe to a degassed solution of 1.11 g (1.93 mmol) of compound (2) in 13 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100 0 C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O (5:1)]. This gives the title compound as a yellow solid (0.77 g, 12.1 mmol, 63% of theory).
1 H NMR (400.1 MHz): δ 1.65 (s, 3H), 2.21 (s, 6H), 2.27 (s, 6H), 3.29 (dd, 1 H), 3.68 (dt, 1 H), 3.75 (s, 5H), 3.77 (d, 1 H), 4.17 (d, 1 H), 6.74 (s, 1 H), 6.92 (s, 1 H), 6.97 (d, 2H), 6.99 (d, 2H), 7.07-7.14 (m, 2H), 7.14-7.20 (m, 3H), 7.33-7.42 (m, 3H), 7.55-7.66 (m, 2H). 31 P-NMR (162.0 MHz): δ -22.2 (d), -11.5 (d).
Example A4: Preparation of (S p )-1-diphenylphosphino-2-dicyclohexylphosphinomethyl- 3-phenylferrocene
a) Preparation of compound (3)
The compound (3) is described in the literature: W. Weissensteiner et al., J. Org. Chem., 66
(2001) 8912-9.
b) Preparation of compound (4)
0.66 g (0.5 mmol) of Pd(PPh 3 J 4 is added to a degassed mixture of 6.65 g (13.2 mmol) of compound (3) in 125 ml of toluene, 3.22 g (26.4 mmol) of phenylboronic acid in 14 ml of ethanol and 27.7 ml of a 2 M aqueous Na 2 CO 3 solution at room temperature. The reaction mixture is degassed once more and refluxed for 16 hours. The mixture is allowed to cool and the organic phase is separated off and then washed with water and saturated aqueous NaCI solution and dried over MgSO 4 . The solvent is removed under reduced pressure and the crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O:Et 3 N (30:3:1)]. This gives the compound (4) as a yellow oil (3.0 g, 6.2 mmol, 50% of theory). 1 H NMR (400.1 MHz): δ 1.11 (d, 3H), 2.20 (s, 3H), 3.09 (dq, 1H), 3.15 (s, 3H), 3.44 (s, 2H), 3.99 (s, 5H), 4.07 (d, 1 H), 4.18 (t, 1H), 4.20-4.22 (m, 1H), 4.41 (dd, 1H), 7.01-7.10 (m, 3H), 7.10-7.21 (m, 5H), 7.38-7.45 (m, 2H).
c) Preparation of compound (5)
3.8 ml (4.9 mmol) of s-butyllithium (1.3 M in cyclohexane) are added dropwise by means of a syringe to a degassed solution of 1.7 g (3.8 mmol) of compound (4) in 15 ml of absolute diethyl ether at 0°C. The reaction mixture is stirred at 0°C for 2 hours. 1.39 g (6.29 mmol) of CIPPh 2 are added thereto, and the mixture is stirred for another hour at 0 0 C and subsequently for 16 hours at room temperature. Water is added and the aqueous phase is extracted with dichloromethane. The combined organic phases are washed with saturated aqueous NaCI solution, dried over MgSO 4 and freed of the solvent under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O:Et 3 N (30:1 :1)]. This gives the desired product as a yellow foam (1.62 g, 2.54 mmol, 68% of theory). 1 H NMR (400.1 MHz): δ 0.66 (d, 3H), 1.79 (s, 3H), 2.68 (dq, 1H), 2.85 (s, 3H), 3.68-3.71 (m, 1 H), 3.71 (d, 1 H), 3.88 (s, 5H), 4.02 (d, 1H), 4.05 (dd, 1H), 4.58 (d, 1 H), 7.00-7.05 (m, 2H), 7.11-7.20 (m, 4H), 7.21-7.29 (m, 5H), 7.29-7.36 (m, 2H), 7.36-7.42 (m, 3H), 7.59-7.66 (m, 4H). 31 P-NMR (162.0 MHz): δ -21.0 (s).
d) Preparation of the title compound (A4)
0.43 ml (2.12 mmol) of HPCy 2 is added dropwise by means of a syringe to a degassed solution of 0.9 g (1.41 mmol) of compound (5) in 50 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100 0 C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The
organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O (50:1)]. This gives the desired product as a yellow solid (0.68 g, 1.04 mmol, 74% of theory).
1 H NMR (400.1 MHz): δ . 0,6^9 (m, 22H), 2.98 (dd, 1 H), 3.06 (d, 1H), 3.80 (s, 5H), 4.08 (d, 1 H), 4.53 (d, 1H), 7.14-7.25 (m, 5H), 7.27-7.31 (m, 1H), 7.33-7.43 (m, 5H), 7.61-7.69 (m, 4H). 31 P-NMR (162.0 MHz): δ -22.6 (d), 6.9 (d).
Example A5: Preparation of (S p )-1-diphenylphosphino-2-di-f-butylphosphinomethyl- 3-phenylferrocene (A5)
5.2 ml (2.82 mmol) of a solution of HP(f-Bu) 2 in acetic acid (10%) are added dropwise by means of a syringe to a degassed solution of 1.2 g (1.88 mmol) of compound (5) in 50 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100°C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O (50:1)]. This gives the title compound (A5) as a yellow solid (0.86 g, 1.42 mmol, 74% of theory).
1 H NMR (400.1 MHz): δ 0.54 (d, 9H), 1.11 (d, 9H), 3.14 (s, 2H), 3.77 (s, 5H), 4.15 (d, 1 H), 4.48 (d, 1H), 7.15-7.24 (m, 3H), 7.27-7.34 (m, 3H), 7.34-7.42 (m, 5H), 7.57-7.63 (m, 2H), 7.64-7.72 (m, 2H). 31 P-NMR (162.0 MHz): δ -23.5 (d), 36.9 (d).
Example A6: Preparation of (S p )-1-diphenylphosphino-2-bis(3,5-dimethylphenyl)phosphino- methyl-3-phenylferrocene (A6)
2.48 ml of a solution of HP[3,5-(CH 3 ) 2 C 6 H 3 ] 2 (0.6 g, 2.49 mmol) in toluene (24.3%) are added dropwise by means of a syringe to a degassed solution of 0.86 g (1.71 mmol) of compound (5) in 13 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100°C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O (10:1)]. This gives the title compound (A6) as a yellow solid (0.7 g, 1.0 mmol, 59% of theory).
1 H NMR (400.1 MHz): δ 2.05 (s, 6H), 2.20 (s, 6H), 3.58 (dd, 1 H), 3.75 (dt, 1 H), 3.81 (s, 5H), 4.02 (d, 1 H), 4.46 (d, 1H), 6.51 (d, 2H), 6.72 (s, 1H), 6.77 (s, 1H), 6.88 (d, 2H), 7.12-7.25 (m,
8H), 7.35-7.43 (m, 5H), 7.60-7.69 (m, 2H). ^ 1 P-NMR (162.0 MHz): δ -22.6 (d), -7.7 (d).
Example A7: Preparation of (S p J-i-diphenylphosphino^-dicyclohexylphosphinomethyl- 3-(3,5-dimethylphen-1-yl)ferrocene(A7)
a) Preparation of compound (6)
0.12 g (0.1 mmol) of Pd(PPh 3 J 4 is added to a degassed mixture of 1.0 g (2 mmol) of compound 3 in 20 ml of toluene, 0.6 g (4 mmol) of (3,5-dimethylphen-1-yl)boronic acid in 3 ml of ethanol and 4.2 ml of a 2M aqueous Na 2 CO 3 solution at room temperature. The reaction mixture is degassed once more and refluxed for 16 hours. The mixture is allowed to cool and the organic phase is separated off and washed with water and saturated aqueous NaCI solution and dried over MgSO 4 . The solvent is removed under reduced pressure and the crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O:Et 3 N (20:1 :0.2)]. This gives compound (6) as a yellow oil (0.8 g, 1.6 mmol, 80% of theory). 1 H NMR (400.1 MHz): δ 1.14 (d, 3H), 2.21 (s, 3H), 2.23 (s, 6H), 3.15 (dq, 1H), 3.16 (s, 3H), 3.40, 3.44 (m, 2H), 3.99 (s, 5H), 4.07 (d, 1 H), 4.17 (t, 1H), 4.19-4.23 (m, 1 H), 4.39 (dd, 1 H), 6.79 (s, 1H), 7.00-7.05 (m, 2H, Ph), 7.07 (s, 2H), 7.05-7.10 (m, 1H), 7.10-7.17 (m, 2H).
b) Preparation of compound (7)
5.8 ml (7.6 mmol) of s-butyllithium (1.3 M in cyclohexane) are added dropwise by means of a syringe to a degassed solution of 2.8 g (5.8 mmol) of compound (6) in 35 ml of absolute diethyl ether at O 0 C. The reaction mixture is stirred at 0 0 C for 2 hours. 1.93 g (8.7 mmol) of
CIPPh 2 are added thereto, and the mixture is then stirred for another hour at 0°C and subsequently for 16 hours at room temperature. Water is added and the aqueous phase is extracted with dichloromethane. The combined organic phases are washed with saturated aqueous NaCI solution, dried over MgSO 4 and freed of the solvent under reduced pressure.
The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O:Et 3 N (30:1 :0.3)].
This gives compound (7) as a yellow foam (3.25 g, 4.88 mmol, 84% of theory).
1 H NMR (400.1 MHz): δ 0.67 (d, 3H), 1.83 (s, 3H), 2.35 (s, 6H), 2.66 (dq, 1H), 2.88 (s, 3H),
3.71 (d, 1 H), 3.75 (d, 1H), 3.86 (s, 5H), 4.00 (d, 1 H), 4.06 (dd, 1 H), 4.56 (d, 1H), 6.90 (s, 1H), 6.98-7.03 (m, 2H), 7.12-7.19 (m, 4H), 7.20-7.29 (m, 6H), 7.36-7.41 (m, 3H), 7.59-7.66 (m, 2H). 31 P-NMR (162.0 MHz): δ -21.1 (s).
c) Preparation of compound (A7)
0.48 ml (2.39 mmol) of HP(C 6 Hn) 2 is added dropwise by means of a syringe to a degassed solution of 1.06 g (1.59 mmol) of compound (7) in 50 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100 0 C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O (50:1)]. This gives the title compound as a yellow foam (0.62 g, 1.04 mmol, 57% of theory).
1 H NMR (400.1 MHz): δ . 0-.6flB4 (m, 22H), 2.43 (s, 6H), 3.04 (dd, 1H), 3.10 (dd, 1H), 3.86 (s, 5H), 4.11 (d, 1 H), 4.56 (d, 1H), 6.98 (s, 1H), 7.21-7.29 (m, 5H), 7.31 (s, 2H), 7.40-7.49 (m, 3H), 7.66-7.76 (m, 2H). 31 P-NMR (162.0 MHz): δ -22.5 (d), 7.3 (d).
Example A8: Preparation of (S p )-1-diphenylphosphino-2-di-f-butylphosphinomethyl- 3-(3,5-dimethylphen-1 -yl)ferrocene (A8)
3.3 ml (1.80 mmol) of a solution of HP(f-Bu) 2 in acetic acid (10%) are added dropwise by means of a syringe to a degassed solution of 0.75 g (1.12 mmol) of compound (7) in 10 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100°C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O (50:1)]. This gives the title compound as an orange foam (0.6 g, 0.95 mmol, 85% of theory).
1 H NMR (400.1 MHz): δ 0.56 (d, 9H), 1.08 (d, 9H), 2.36 (s, 6H), 3.08-3.19 (m, 2H), 3.76 (s, 5H), 4.12 (d, 1H), 4.46 (dd, 1H), 6.91 (s, 1 H), 7.15-7.24 (m, 5H), 7.27-7.33 (m, 2H), 7.33-7.41 (m, 3H), 7.64-7.72 (m, 2H). 31 P-NMR (162.0 MHz): δ -23.4 (d), 36.2 (d).
Example A9: Preparation of (S p )-1-diphenylphosphino-2-bis(3,5-dimethylphosphino)methyl-3-
(3,5-dimethylphen-1 -yl)ferrocene (A9)
0.2 ml of a solution of HP[3,5-(CH 3 ) 2 C 6 H 3 ] 2 (54 mg, 0.22 mmol) in toluene (24.3%) is added
dropwise by means of a syringe to a degassed solution of 0.1 g (0.15 mmol) of compound (7) in 5 ml of acetic acid. The reaction mixture is degassed once more and stirred at 100 0 C for 16 hours. The acetic acid is subsequently removed under reduced pressure. The residue is dissolved in CH 2 CI 2 and washed with saturated aqueous NaHCO 3 solution, water and saturated aqueous NaCI solution. The organic phase is dried over MgSO 4 and the solvent is removed under reduced pressure. The crude product is purified by means of chromatography [AI 2 O 3 , PE:Et 2 O (30:1)]. This gives the title compound as an orange foam (50 mg, 0.07 mmol, 46 %).
1 H NMR (400.1 MHz): δ 2.06 (s, 6H), 2.19 (s, 6H), 2.28 (s, 6H), 3.61 (dd, 1H), 3.72 (br d, 1 H), 3.80 (s, 5H), 4.00 (d, 1H), 4.43 (d, 1 H), 6.54 (d, 2H), 6.73 (s, 1H), 6.76 (s, 1 H), 6.83 (s, 1 H), 6.88 (d, 2H), 7.00 (s, 2H), 7.12-7.21 (m, 5H), 7.35-7.40 (m, 3H), 7.59-7.69 (m, 2H). 31 P-NMR (162.0 MHz): δ -22.4 (d), -7.4 (d).
B) Preparation of metal complexes
Example B1 :
5.1 mg (0.0136 mmol) of [Rh(nbd) 2 ]BF 4 and 10.4 mg (0.0163 mmol) of ligand A1 from Example A6 are weighed into a Schlenk vessel provided with a magnetic stirrer and the air is displaced by means of vacuum and argon. After addition of 0.8 ml of degassed methanol with stirring, an orange solution of the metal complex (catalyst solution) is obtained. A uniform, C2-symmetric complex is formed.
C) Use examples
Example C1 : Hydrogenation of unsaturated compounds
The method of carrying out the hydrogenations and the determination of the optical yields ee is described in general terms by W. Weissensteiner et al. in Organometallics 21 (2002), pages 1766-1774. The catalysts are prepared in "in situ" by mixing ligand and metal complex as catalyst precursor (= [Rh(norbomadiene) 2 ]BF 4 unless indicated otherwise) in the solvent. Unless indicated otherwise, the substrate concentration is 0.25 mol/l, and the molar ratio of substrate to metal = 200 and the molar ratio of ligand to metal = 1.05.
Hydrogenations:
Reaction conditions for the substrates MAC and DMI:
Molar ratio of substrate to metal = 200; catalyst precursor = [Rh(norbornadiene) 2 ]BF 4 ; solvent
= MeOH; hydrogen pressure = 1 bar; temperature = 25°C; reaction time 1 hour.
MAC:
DMI:
Reaction conditions for the substrate MEξA:
Molar ratio of substrate to metal = 100; catalyst precursor = [Ir(COD)CI] 2 ; solvent = toluene; additions: 2 equivalents of tetrabutylammonium iodide per equivalent of Ir and 0.03 ml of trifluoroacetic acid per 10 ml of toluene; hydrogen pressure = 80 bar; temperature = 25°C; reaction time = 16 hours.
MEA:
The results of the hydrogenation are reported in Table 1 below, "ee" is the enantiomeric excess. The configuration is indicated in brackets. It can be seen from the results with the comparative ligand and substituted ligands in Table 1 that the substitution can surprisingly influence and invert the configuration. Furthermore, the increase in the optical yields on introduction of substituents can be seen.
The structures of the comparative ligands C1 , C2 and C3 are given below:
Table 1 :
Example C2: Preparation of N-(2'-methyl-6'-ethylphen-1'-yl)-1-methoxymethylethylamine 1.65 mg of [lr(cyclooctadiene)CI] 2 , 2.8 mg of ligand, 70 mg of tetrabutylammonium iodide and 10 ml of acetic acid are added to 105 g of imine (1) in an autoclave. The conditions correspond to a ratio of substrate to iridium of 100 000. The autoclave is closed and flushed with argon. The argon is then replaced by flushing with hydrogen and the autoclave is pressurized with hydrogen (80 bar). The hydrogenation is started by switching on the stirrer. After the hydrogenation, the conversion and the optical yield (ee) are determined by means of HPLC [Chiracel OD; eluent hexane/i-propanol (99.6:0.4), flow: 1 ml/minute]. The results are reported in Table 2 below, including the configuration for the optical yield (R or S configuration).
Table 2:
*) The product having the inverse configuration is obtained by use of the ligands in their other enantiomeric form.