Stereoselective alkylation of C2-symmetric chiral N-phthaloylglycinamides in the preparation of enantiopure α-amino acids
摘要:
The novel, chiral glycinamides (S,S)-3 and (S,S)-4 were prepared in good yields from C-2-symmetric chiral amines (S,S)-1 and (S,S)-2, respectively. Enolate formation and addition to methyl iodide and benzyl bromide proceeded in good yield and high diastereoselectivity, especially in the presence of LiCl or DMPU. Removal of the phthaloyl protecting group with hydrazine, followed by hydrolysis with 6N HCl, converted the benzylated product (S,S,S)-7 to enantiopure (S)-phenylalanine. (C) 2000 Elsevier Science Ltd. All rights reserved.
C−H Carbene Insertion of α-Diazo Acetamides by Photolysis in Non-Conventional Media
作者:Nuno R. Candeias、Pedro M. P. Gois、Luis F. Veiros、Carlos A. M. Afonso
DOI:10.1021/jo800980c
日期:2008.8.1
Light from a mercury vapor high-pressure lamp was used to induce the photolytic decomposition of alpha-diazo acetamides in hexane and in nonconventional media such as water or a film. The corresponding beta- and/or gamma-lactams were obtained in reasonable yields and in some cases with good diastereoselectivities with no need to use a metallic catalyst. Experimental studies on chiral substrates demonstrated the occurrence of insertion with retention of configuration.