Asymmetric synthesis of .alpha.-alkyl-.alpha. amino acids from chromium-carbene-complex-derived .beta.-lactams
摘要:
Optically active bicyclic beta-lactam 3 was synthesized by photolysis of optically active oxazolidine carbene chromium complex 1 with oxazine 2. Conversion of the oxazolidine to the oxazolidinone gave a bicyclic beta-lactam readily alpha-alkylated. Cleavage of the alkylated beta-lactam gave optically active ester aldehyde 7, which was converted to a number of optically active alpha-alkyl-alpha-amino acids. These include (R)-alpha-methylserine, (S)-alpha-methylglutamic acid, (S)-alpha-methylornithine, (S)-vinylalanine, (S)-ethynylalanine, and (S)-2-methyl-2,3-diaminopropionic acid.
Asymmetric synthesis of .alpha.-alkyl-.alpha. amino acids from chromium-carbene-complex-derived .beta.-lactams
摘要:
Optically active bicyclic beta-lactam 3 was synthesized by photolysis of optically active oxazolidine carbene chromium complex 1 with oxazine 2. Conversion of the oxazolidine to the oxazolidinone gave a bicyclic beta-lactam readily alpha-alkylated. Cleavage of the alkylated beta-lactam gave optically active ester aldehyde 7, which was converted to a number of optically active alpha-alkyl-alpha-amino acids. These include (R)-alpha-methylserine, (S)-alpha-methylglutamic acid, (S)-alpha-methylornithine, (S)-vinylalanine, (S)-ethynylalanine, and (S)-2-methyl-2,3-diaminopropionic acid.
A contribution to the confusion surrounding the reaction of ketenes with imines to produce .beta.-lactams. A comparison of stereoselectivity dependence on the method of ketene generation: acid chloride/triethylamine vs photolysis of chromium carbene complexes
作者:Louis S. Hegedus、John Montgomery、Yukitoshi Narukawa、Daniel C. Snustad
DOI:10.1021/ja00015a036
日期:1991.7
The stereoselectivity of the reaction of imines of benzaldehyde and cinnamaldehyde with ketenes generated by the reaction of optically active oxazolidinone acid chlorides with triethylamine and complexed ketenes generated by photolysis of optically active oxazolidine ― and oxazolidinone-chromium-carbene complexes in the presence and absence of added triethylamine was compared. The absolute stereochemistry
Asymmetric synthesis of .alpha.-alkyl-.alpha. amino acids from chromium-carbene-complex-derived .beta.-lactams
作者:Pierre Jean Colson、Louis S. Hegedus
DOI:10.1021/jo00074a016
日期:1993.10
Optically active bicyclic beta-lactam 3 was synthesized by photolysis of optically active oxazolidine carbene chromium complex 1 with oxazine 2. Conversion of the oxazolidine to the oxazolidinone gave a bicyclic beta-lactam readily alpha-alkylated. Cleavage of the alkylated beta-lactam gave optically active ester aldehyde 7, which was converted to a number of optically active alpha-alkyl-alpha-amino acids. These include (R)-alpha-methylserine, (S)-alpha-methylglutamic acid, (S)-alpha-methylornithine, (S)-vinylalanine, (S)-ethynylalanine, and (S)-2-methyl-2,3-diaminopropionic acid.