Simple and efficient synthesis of bicyclic enol-carbamates: access to brabantamides and their analogues.

A novel synthetic approach towards the formation of the unusual bicyclic enol-carbamates, as found in brabantamides A-C, is reported. The bicyclic oxazolidinone framework was obtained in very good yield and with high E / Z selectivity from a readily available β-ketoester under mild reaction conditions using Tf 2 O and 2-chloropyridine tandem. The major E isomer was used in the synthesis of the brabantamide A analogue.