Crossed acyloin condensation of aliphatic aldehydes

Crossed acyloins were efficiently prepared by the thiazolium-catalysed cond ensation of two different unhindered aldehydes, using one mol equivalent of one aldehyde with three mol equivalents of the other. Conversion into the corresponding nonsymmetrical 1,2-dioxime was achieved either by oxidation w ith bismuth(III) oxide or the Dess-Martin periodinane to give a 1,2-diketon e that was then treated with hydroxylamine to give the oxime.