A new synthesis of β-lactams via photochemical γ-hydrogen abstraction of monothioimides

Abstract

Photochemical reactions of acyclic and semicyclic monothioimides were studied. Photolysis of acyclic monothioimides gave β-lactams (Type II cyclization products) and thioamides (Type II cleavage products). 4-Mercapto-β-lactams were isolated as 4-acylthio-β-lactams by acylation with benzoyt chloride or acetyl chloride in the presence of triethylamine. Irradiation of six- or seven- membered semicyclic monothioimides gave bicyclic β-lactams, but five-membered semicyclic monothioimides gave only Type II cleavage products.