Unusual amino acids III. Asymmetric synthesis of 3-arylalanines
摘要:
21 (Z)-alpha-N-benzoylamino-beta-arylacrylic acids and their esters were prepared by known procedures and hydrogenated to the corresponding optically active alpha-benzoyl-beta-arylalanine derivatives with optical yields in the range of 82-95% ee using the cationic rhodium complex of ''PROPRAPHOS'' as the chiral catalyst No electronical influences of the substituents at the aryl moiety on the enantioselectivity were observed but a sterical one, proved by X-ray crystallographic analysis and computer-aided modellings. Deacylation of the hydrogenated spezies produced the hydrochlorides of the 3-arylalanines attended by a partial racemisation In this case the hydrogenation of urethane type protected dehydroaminoacid derivatives seems to be the alternative.
Unusual amino acids III. Asymmetric synthesis of 3-arylalanines
摘要:
21 (Z)-alpha-N-benzoylamino-beta-arylacrylic acids and their esters were prepared by known procedures and hydrogenated to the corresponding optically active alpha-benzoyl-beta-arylalanine derivatives with optical yields in the range of 82-95% ee using the cationic rhodium complex of ''PROPRAPHOS'' as the chiral catalyst No electronical influences of the substituents at the aryl moiety on the enantioselectivity were observed but a sterical one, proved by X-ray crystallographic analysis and computer-aided modellings. Deacylation of the hydrogenated spezies produced the hydrochlorides of the 3-arylalanines attended by a partial racemisation In this case the hydrogenation of urethane type protected dehydroaminoacid derivatives seems to be the alternative.
Enzymic asymmetric synthesis of .alpha.-amino acids. Enantioselective cleavage of 4-substituted oxazolin-5-ones and thiazolin-5-ones
作者:Joyce Z. Crich、Rosario Brieva、Peer Marquart、Rui Lin Gu、Steffen Flemming、Charles J. Sih
DOI:10.1021/jo00064a010
日期:1993.6
A general enzymatic asymmetric synthesis of L-alpha-amino acids has been developed. This method entails the use of the Pseudomonas cepacia lipase (P-30) to catalyze the enantioselective methanolysis of a variety of 4-substituted 2-phenyloxazolin-5-one derivatives in a nonpolar organic solvent to furnish optically-active N-benzoyl-L-alpha-amino acid methyl esters (ee = 66-98%), which in turn is subjected to a protease-catalyzed kinetic resolution yielding enantiomerically-pure N-benzoyl-L-alpha-amino acids. This synergistic coupling of two enzymes allows the ready preparation of L-alpha-amino acids of high enantiopurity in yields greater than 50%, an inherent advantage over conventional resolution procedures. Two proteases were found to catalyze the enantioselective hydrolysis of a variety of 4-substituted 2-phenylthiazolin-5-one derivatives to give N-(thiobenzoyl)-L-alpha-amino acids of high optical purity.
US5219731A
申请人:——
公开号:US5219731A
公开(公告)日:1993-06-15
Unusual amino acids III. Asymmetric synthesis of 3-arylalanines
21 (Z)-alpha-N-benzoylamino-beta-arylacrylic acids and their esters were prepared by known procedures and hydrogenated to the corresponding optically active alpha-benzoyl-beta-arylalanine derivatives with optical yields in the range of 82-95% ee using the cationic rhodium complex of ''PROPRAPHOS'' as the chiral catalyst No electronical influences of the substituents at the aryl moiety on the enantioselectivity were observed but a sterical one, proved by X-ray crystallographic analysis and computer-aided modellings. Deacylation of the hydrogenated spezies produced the hydrochlorides of the 3-arylalanines attended by a partial racemisation In this case the hydrogenation of urethane type protected dehydroaminoacid derivatives seems to be the alternative.