Addition of Metal Cyanides toTosylhydrazones of Aldehydes in Aprotic Solvents: A NewMethod for One-Carbon Homologation of Aldehydes and forthe Synthesis of α-(N 2-Tosylhydrazino)nitriles

Abstract

One-carbon homologation of aldehydes to nitriles via reaction of the respective tosylhydrazones with trimethylsilyl cyanide, tributyltin cyanide and diethylaluminum cyanide with or without Lewis acid-type catalysts was examined. Representative tosylhydrazones on treatment with trimethylsilyl cyanide in the presence of trimethylsilyl triflate or scandium triflate afforded α-(N 2-tosylhydraziono)nitriles in excellent yields. The same adducts were also obtained using tributyltin cyanide/scandium triflate system or diethylaluminum cyanide at room temperature. Treatment of tosylhydrazones with trimethylsilyl cyanide/scandium triflate or with diethylaluminum cyanide in appropriate solvent at higher temperatures afforded the respective one-carbon extended nitriles in good yields. Some examples of the application of these reactions to polyfunctional compounds are given.