β-, γ-, and δ-Amino acids were easily cyclized in high yields to corresponding β-, γ-, and δ-lactams by treatment with N-alkyl-2-benzothiazolylsulfenamide and triphenylphosphine.
The asymmetric synthesis of β-lactam antibiotics - IV. A formal synthesis of thienamycin.
作者:David A. Evans、Eric B. Sjogren
DOI:10.1016/s0040-4039(00)85107-2
日期:1986.1
Oxidative cleavage of crotonate imide aldol adduct 6b provides the configurationally stable aldehyde 4. Transformation of this aldehyde to enantiomerically pure β-lactams is described.
Titanium enolate-mediated aldol reaction of N-phthaloyl-beta-alanyl-1, 3-benzoxazinone 5 with acetaldehyde gave the (+/-)-syn-aldol (+/-)-6 in a high yield with high diastereoselectivity. Lipase-catalyzed hydrolysis of the corresponding laurate (+/-)-7b furnished enantiomerically pure (2S, 3R)-N-(2-phthaloylaminomethyl-3-hydroxybutyryl)-1, 3-benzoxazinone 6 in 49% yield. Silylation of the hydroxy group of (29, 3R)-6 follwed by deprotection of the amino and carboxy groups gave the beta-amino acid derivative 9 which was transformed into the acetoxyazetidinone 3, a key intermediate of penems and carbapenems. Copyright (C) 1996 Elsevier Science Ltd