Enantioselective Synthesis of Functionalized 1-Benzoxepines by Phenoxide Ion Mediated 7-endo-tet Carbocyclization of Cyclic Sulfates

A new asymmetric synthesis of 2,3-disubstituted 1-benzoxepines is described. Key steps include Sharpless asymmetric dihydroxylation of trans-a,p-unsaturated esters and phenoxide ion mediated intramolecular 7-endo-tet carbocyclization of syn-2,3-dihydroxy ester derived cyclic sulfates. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)