A Single-Step Synthesis of 4-Oxazolin-2-ones and Their Use in the Construction of Polycyclic Structures Bearing Quaternary Stereocenters

A new method for the synthesis of 4-oxazolin-2-ones by a one-pot MW-promoted condensation of alpha-ketols and isocyanates is reported. An alternative thermal approach using, the same starting materials is also described. These cyclic enamides were efficient nucleophiles, reacting with Michael acceptors and prenyl bromide to give a variety of polycyclic structures bearing one or two quaternary stereocenters. The selectivity of the products depended on the reaction conditions and on the electrophile used. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)