摘要:
A process for for producing a (2R,3S)-cyclohexylnorstatine or a salt thereof is disclosed, which comprises the steps of: enantioselectively hydrogenating a 4-cyclohexyl-2-halogeno-3-oxobutyric acid ester in the presence of a ruthenium-phosphine complex to produce a 4-cyclohexyl-2-halogeno-(3R)-hydroxybutyric acid ester (2); epoxidizing the compound (2) in the presence of a base to produce a 4-cyclohexyl-(2S,3R)-epoxybutyric acid ester (3); reacting the compound (3) with a lower trialkylsilyl azide in the presence of a Lewis acid to produce a (3S)-azide-4-cyclohexyl-(2S)-substituted butyric acid ester (4); subjecting the compound (4) to hydrogenolysis to produce a (2S,3S)-cyclohexylnorstatine derivative (5); and inverting the configuration at the 2-position of the compound (5).
摘要:
A process for preparing optically active 4-methyl-2-oxetanone which comprises asymmetrically hydrogenating 4-methylene-2-oxetanone in the presence of a ruthenium-optically active phosphine complex. Optically active 4-methyl-2-oxetanone can easily and economically be obtained at high optical purity.
摘要:
A process for preparing optically active 4-methyl-2-oxetanone which comprises asymmetrically hydrogenating 4-methylene-2-oxetanone in the presence of a ruthenium-optically active phosphine complex. Optically active 4-methyl-2-oxetanone can easily and economically be obtained at high optical purity.
摘要:
A process for producing an optically active alcohol represented by formula (I): ##STR1## wherein R.sub.1 is an alkyl group having from 2 to 11 carbon atoms, an alkenyl group having from 3 to 11 carbon atoms, an alkadienyl group having from 6 to 11 carbon atoms, a cyclohexyl group, an cyclohexylmethyl group, or a cyclohexylethyl group, provided that the olefin in the alkenyl group or alkadienyl group is not conjugated to the olefin at the 2-position thereof; and * means an asymmetric carbon atom,is disclosed, comprising subjecting an olefinic alcohol represented by formula (II): ##STR2## wherein R.sub.1 is the same as defined above to asymmetric hydrogenation in the presence of, as a catalyst, a ruthenium-optically active phosphine complex.According to the process of the invention, the desired optically active alcohols which are useful not only as intermediates for the manufacture of perfumes and vitamin E but also as liquid crystal materials can be produced with high optical purities.
摘要:
A process for preparing carnitine which comprises asymmetrically hydrogenating a .gamma.-halogeno-.beta.-keto ester represented by formula (I): ##STR1## wherein X represents a chlorine atom or a bromine atom; and R represents a lower alkyl group, in the presence of a ruthenium-optically active phosphine complex represented by formula (II), (III) or (IV):Ru.sub.2 Cl.sub.4 (L).sub.2 (C.sub.2 H.sub.5).sub.3 N (II)Ru(OCOR.sup.2).sub.2 (L) (IV)RuX.sub.2 (L) (V)wherein L represents 2,2'-bis(di-p-R.sup.1 -phenylphosphino)- 1,1'-binaphthyl of formula (III): ##STR2## wherein R.sup.1 represents a hydrogen atom, a methyl group, or a t-butyl group;R.sup.2 represents a lower alkyl group or a trifluoromethyl group; and X is as defined above,as a catalyst at a temperature of from 70.degree. to 150.degree. C. to obtain an optically active alcohol represented by formula (VI): ##STR3## wherein X and R are as defined above, and then reacting the optically active alcohol as obtained with trimethylamine without isolation, is disclosed.
摘要:
A ruthenium-phosphine complex represented by formula (I): ##STR1## wherein R represents a hydrogen atom, a methyl group, or a methoxy group; S represents a tertiary amine; when y is 0, then x is 2, z is 4, and p is 1; and when y is 1, then x is 1, z is 1, and p is 0. The complex is inexpensive and exhibits excellent performance as a catalyst for various organic syntheses, and particularly asymmetric hydrogenation.
摘要:
A novel chiral unsymmetric diphosphine compound of formula (I): ##STR1## wherein Ar.sup.1 and Ar.sup.2, which are different from each other, each represent a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a pyridyl group, a quinolyl group, an isoquinolyl group, a furfuryl group, a benzofurfuryl group, a thienyl group, or a benzothienyl group, and a transition metal complex containing the diphosphine compound as a ligand. The complex catalyzes various asymmetric synthesis reactions, e.g., asymmetric hydrogenation or asymmetric hydrosilylation, exhibiting excellent performance in selectivity, conversion and catalytic activity, to provide a product of desired absolute configuration at high optical purity and in high yield.
摘要:
A process for preparing an optically active (2S,3S)-allophenylnorstatin derivative (I) is disclosed, comprising asymmetrically hydrogenating a 4-phenyl-2-halogeno-3-oxobutyric ester (III) in the presence of a ruthenium-phosphine complex to obtain a 4-phenyl-(2S)-halogeno-(3R)-hydroxybutyric ester (IV), epoxidizing the ester (IV) in the presence of a base to obtain a 4-phenyl-(2S,3R)-epoxybutyric ester (V), reacting the ester (V) with a tri(lower alkyl)silylazide or a (lower alkyl)diarylsilylazide in the presence of a Lewis to obtain a (3S)-azido-4-phenyl-(2S)-trisubstituted silyloxybutyric ester (VI), hydrogenolyzing the ester (VI) into a (2S,3S)-allophenylnorstatin derivative (VII), protecting the amino group of the compound (VII), and, if desired, hydrolyzing the compound before or after the amino group protection. Compounds (I) can be obtained at high optical purity safely and in good yield.
摘要:
A process for producing an optically active .gamma.-butyrolactone derivative represented by formula (II): ##STR1## wherein R.sup.1 represents an alkyl group having from 1 to 10 carbon atoms or a substituted or unsubstituted phenyl group; and * indicates an asymmetric carbon atom, is disclosed, comprising enantioselectively hydrogenating a .gamma.-keto acid or an ester thereof represented by formula (I): ##STR2## wherein R.sup.1 and * are as defined above; and R.sup.2 represents a hydrogen atom or a lower alkyl group, in the presence of an optically active ruthenium-phosphine complex. The compounds (I) can be obtained at high optical purity through simple operations and a reduced number of steps.
摘要:
A process for producing an .alpha.-hydroxyketone represented by formula (I): ##STR1## wherein R.sup.1 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or an alkoxycarbonyl group; and R.sup.2 and R.sup.3 each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aralkyl group, provided that they do not simultaneously represent a hydrogen atom; or a pair of R.sup.1 and R.sup.2, a pair of R.sup.1 and R.sup.3, or a pair of R.sup.2 and R.sup.3 is taken together to form a ring; and the pair of R.sup.1 and R.sup.2 and the pair of R.sup.2 and R.sup.3 may form a ring simultaneously, is disclosed, comprising reacting a compound represented by formula (II): ##STR2## wherein R.sup.1, R.sup.2, and R.sup.3 are as defined above, with an oxidizing agent in the presence of a ruthenium compound and water. .alpha.-Hydroxyketones useful as physiologically active substances are produced with good selectivity and in high yield.