A diastereoselective synthesis of (±) cis-β-lactams (5 & 6) via cycloaddition reactions of N1-(α-thiophenyl)benzyl imines (3) with acid chlorides (4) in the presence of triethylamine is described. The deprotection of N1-(α-thiophenyl)benzyl group has been achieved by oxidation using potassium persulfate to give N-unsubstituted β-lactams (7) in good yields.
An efficient use of triphosgene, as an acid activator, for the synthesis of substituted azetidin-2-ones via ketene-imine cyclo-addition reaction using various acids and imines have been described. (C) 2002 Elsevier Science Ltd. All rights reserved.
Stereoselective Synthesis of cis-Bis-β-lactams Linked with an Ethylene Bridge
An efficient synthesis of (+/-)-cis-bis-beta -lactams (5 and 6) via cycloaddition reaction of bisimines (3a-c) with acid chlorides (4) in the presence of triethylamine in very good yield is described. (C) 2000 Published by Elsevier Science Ltd.