Large scale preparation of 2,4-dihydroxybenzaldehyde using a variation of the Vilsmeierhaack reaction and isolated intermediates

摘要

A novel process for producing chiral hydroxylamines for use as intermediates to make chiral hydroxyureas, which process comprises a tandem condensation-cyclization reaction between a dimethylsulfoxoniurn methylide and an appropriately substituted nitrone bearing a D- or L- mannose chiral auxiliary to yield a compound of Formula (I) as claimed herein.