The first enantioselective [3+2] cycloaddition of epoxides to arylisocyanates: asymmetric synthesis of chiral oxazolidinone phosphonates

A [3+2] cycloaddition of diethyl 1 2-oxiranephosphonate to aryl isocyanates catalyzed by lanthanide cations is described The reaction is highly regioselective and 5-substituted 2-oxazolidinone phosphonates are obtained with a regioselectivity greater than 95 5 with respect to the 4-substituted regioisomer and in up to 84% yield When 20 mol % of Pybox-Yb3+ is used as a catalyst enantiomerically enriched products are obtained in up to 75% ee depending on the reaction conditions and the nature of the isocyanate Low temperatures benefit asymmetric induction but have an adverse effect on the regioselectivity for para-substituted aryl isocyanates (C) 2010 Elsevier Ltd All rights reserved