Wittig‐Reaktionen mit Cyanhydrinen sowie Redoxreaktion des 4‐Nitromandelsäurenitrils

Abstract

Wittig Reactions of Cyanohydrines and Redox Reaction of 4-Nitromandelonitrile Substitued mandelonitriles 5 (R1  H, OCH3, NO2) react in the presence of sodium tert- butoxide as a base like the corresponding aldehydes with substituted benzylidenetriphenylphosphoranes via the Wittig reaction to yield 4,4′-disubstituted stilbenes 8, for which the (E)/(Z) stereoisomer ratios are given. Our results refer to a reaction with a preceding cyanohydrine-aldehyde equilibrium. 4-Nitromandelonitrile (5a) forms in a basic methanolic solution via a redox reaction a mixture of dimethyl 4,4′-azoxybenzenedicarboxylate (11) and methyl 4-nitrobenzoate (12).