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

1979; Linguagem: Inglês

10.1039/p19790000504

2050-8255

Aristide Vigevani, Maurizio Foglio, Giovanni Franceschi, Paolo Masi, Antonino Suarato, Elena Gandini, G. Palamidessi,

Asymmetric Synthesis and Catalysis

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.