Selective asymmetric hydrogenation of dehydroamino acid derivatives using rhodium and iridium diphosphinite carbohydrate catalyst compositions
AssigneeE. I. Du Pont de Nemours and Company
InventorsTimothy A. Ayers, Thaliyil V. Rajanbabu
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Abstract
A process and catalyst composition are provided for the highly efficient enantioselective hydrogenation of dehydroamino acid derivatives. The catalyst composition comprises rhodium or iridium and a diphosphinite carbohydrate ligand, wherein the phosphorous atoms are attached to aromatic groups substituted with electron-donating substituents. Also provided is a means to selectively produce .alpha. amino acids in either the L or the D form, based upon use of a sugar in the ligand with phosphinites attached in an absolute Right-Left or Left-Right configuration, respectively.
Claims11
A process for asymmetric hydrogenation, comprising:
- reacting a dehydroamino acid derivative of formula I
- ZZC.dbd.C(CO.sub.2 Z)(NHZ) I
- wherein each Z is independently H or a C.sub.1 to C.sub.40 carboalkoxy, C.sub.1 to C.sub.40 aromatic or nonaromatic hydrocarbyl or C.sub.1 to C.sub.40 aromatic or nonaromatic heterocyclic radical;
- optionally substituted with one or more halo, alkoxy, carboalkoxy, nitro, haloalkyl, hydroxy, amido, keto or sulfur containing groups;
- with a source of hydrogen;
- in the presence of a catalyst composition comprising iridium or rhodium and a chiral, nonracemic diphosphinite ligand of formula II
- (R.sup.1).sub.2 --P--X--R.sup.2 --X--P--(R.sup.1).sub.2 II
- wherein R.sup.2 is a C.sub.4 to C.sub.40 dideoxycarbohydrate;
- each X is independently O or NR.sup.3, wherein R.sup.3 is H, C.sub.1 to C.sub.20 alkyl or aryl;
- and
- each R.sup.1 is independently an aromatic hydrocarbyl substituted with one or more amino, dialkylamino, hydroxy, alkoxy, alkyl, trialkylsilyl, trialkyaryl groups or an aromatic heterocycle substituted with one or more amino, dialkylamino, hydroxy, alkoxy, alkyl, trialkylsilyl, or triarylsilyl groups;
- to yield a chiral, nonracemic mixture of compounds of formula III
- ZZCH--CH(CO.sub.2 Z)(NHZ) III
- wherein Z is defined as above.
A process for asymmetric hydrogenation, comprising reacting a dehydroamino acid derivative of formula I
- ZZC.dbd.C(CO.sub.2 Z)(NHZ) I
- wherein each Z is independently H or a C.sub.1 to C.sub.40 carboalkoxy, C.sub.1 to C.sub.40 aromatic or nonaromatic hydrocarbyl or C.sub.1 to C.sub.40 aromatic or nonaromatic heterocyclic radical, optionally substituted with one or more halo, alkoxy, carboalkoxy, nitro, haloalkyl, hydroxy, amido, keto or sulfur containing groups;
- with a source of hydrogen;
- in the presence of a catalyst composition comprising iridium or rhodium and a chiral nonracemic diphosphinite ligand of formula II
- (R.sup.1).sub.2 --P--X--R.sup.2 --X--P--(R.sup.1).sub.2 II
- wherein R.sup.2 is a C.sub.4 to C.sub.40 dideoxycarbohydrate;
- each X is independently O or NR.sup.3, wherein R.sup.3 is H, a C.sub.1 to C.sub.20 alkyl or aryl;
- and
- each R.sup.1 is an unsubstituted aromatic hydrocarbyl to, yield a chiral, nonracemic mixture of compounds of formula III
- ZZCH--CH(CO.sub.2 Z)(NHZ) III
- wherein Z is defined as above;
- and wherein in formula II the X groups are attached to R.sup.2 in the Left-Right diphosphinite configuration whereby the asymmetric hydrogenation process selectively yields compounds of formula III in R-configuration.
Dependencies are inferred from the claim text.