An efficient use of Oppolzer sultam for Diastereospecific Synthesis of cis-β-Lactams
作者:V. Srirajan、Vedavati G. Puranik、A.R.A.S. Deshmukh、Baburao M. Bhawal
DOI:10.1016/0040-4020(96)00193-7
日期:1996.4
DiastereospecificSynthesis of cis-β-Lactams (6a-g) has been achieved in ketene-imine cycloaddition reaction (Staudinger reaction) by using homochiral ketene precursors 3 and 4 derived from Oppolzersultam, in very good yields.
The efficient diastereoselective synthesis of 3-acetoxy/methoxy/phthalimido-beta-lactams 2/2', 3/3' and 4/4' respectively was performed using chiral imines 1 obtained from chiral amines. Factors (solvent, temperature, substituent, steric bulk) influencing the stereoselectivity and the diastereomeric ratio were also studied in detail. The diastereoselectivity of the two isomers was determined from the ratio of integral values of doublets of C3-H and C4-H and from the integral values of H in -CH(Me/Et)Ph/Np of the two diastereomers. Representative pairs of cis-diastereomers were separated by efficient column chromatography. (C) 2016 Elsevier Ltd. All rights reserved.