A Modular Approach to Polyketide Building Blocks: Cycloadditions of Nitrile Oxides and Homoallylic Alcohols
作者:Nina Lohse-Fraefel、Erick M. Carreira
DOI:10.1021/ol0504953
日期:2005.5.1
A general approach to the diastereoselective synthesis of Delta(2)-isoxazolines via magnesium-mediated, hydroxyl-directed diastereoselective nitrile oxide cycloadditions of homoallylic alcohols and monoprotected homoallylic diols is disclosed. A broad spectrum of aliphatic and aromatic nitrile oxides and a variety of homoallylic alcohols participate in the cycloaddition, thus expanding the scope of
starting materials suffice for the modular synthesis of all possible polypropionate diastereomers. This general method for the diastereoselective synthesis of syn, anti, and methyl ketone aldol adducts utilizes a powerful MgII -mediated, hydroxy-directed nitrile oxide cycloaddition. The free hydroxy group provides an ideal synthetic handle enabling the rapid assembly of complex polyketide structures