Novel azetidinone intermediates and their use in the synthesis of 2-(substituted methyl)-penem-3-carboxylates

摘要

The invention relates to novel azetidinone intermediates and to a novel process for the preparation of 2-(substituted methyl)-penem-3-carboxylates, starting from penicillanic acid sulphoxide via a 2-thiacephem derivative or via the novel azetidinone intermediates. The penem compounds, which are obtained as end products in the process according to the invention, have the 5R configuration.