606972-19-4Relevant academic research and scientific papers
A new synthetic approach to 5-dethia-4-methyl-5-oxacephems
Ka?uza, Zbigniew,Kazimierski, Arkadiusz,Lewandowski, Krzysztof,Suwińska, Kinga,Szcz?sna, Beata,Chmielewski, Marek
, p. 5893 - 5903 (2007/10/03)
Starting from (L)-ethyl lactate and 4-vinyloxy-azetidin-2-one the diastereomeric (4S,6R)- and (4S,6S)-4-methyl-5-oxa-3-methylene and 3-oxo-cephams were obtained. The formation of the cepham skeleton proceeds with a diastereomeric excess up to 80%, depending on catalyst and reaction conditions. For comparison, the corresponding racemic cephams lacking a methyl at C-4 or with a gem-dimethyl group at C-4 were synthesized.
