Capture of In Situ Generated Diazo Compounds or Copper Carbenoids by Triphenylphosphine: Selective Synthesis of trans-Alkenes and Unsymmetric Azines via Reaction of Aldehydes with Ketone-Derived N-Tosylhydrazones

Copper(II) acetylacetonate-catalyzed Wittig olefination reactions of aldehydes with ketone-derived N-tosylhydrazones are reported. A series of tosylhydrazones was investigated and our results showed that the carbon number of the alkyl chain influences the E-selecivity of the alkenes greatly. Alkenes could be obtained in moderate yields and excellent E-selectivity when the carbon numbers were up to two. Under metal-free conditions, triphenylphosphine was able to capture the in situ generated diazo compounds and the corresponding unsymmetrical azines were formed in good yields.