Paolo Masi

β-Lactam antibiotics. Part 2. New methods of cyclising hydrazinothioazetidinones to cephem ring systems

Base-induced and oxidative cyclisation of hydrazinothioazetidinones as novel routes to cephem ring systems are described together with the proposed mechanisms. General procedures for these cyclisations are reported.

Azetidinone intermediates for the synthesis of cephem ring systems. Part 1. Chemical shift non-equivalence of the allylic methylene protons

The chemical shift non-equivalence of the allylic methylene groups CH2Br and CH2SPh, present in some azetidinone intermediates useful for the synthesis of cephem ring systems, affords a valuable criterion for establishing the stereochemistry of the double bond. The synthetic procedures used for the preparation of the compounds examined are described.