Propynal Equivalents and Diazopropyne: Synthesis of All Mono-13C Isotopomers

Mechanistic and spectroscopic investigations of reactive C3H2 hydrocarbons necessitated the preparation of diazopropyne isotopomers bearing mono‐13C substitution at each of the three unique positions. The diazo compounds and their tosylhydrazone precursors were prepared from the mono‐13C isotopomers of propynal (in the form of either the aldehyde or the diethyl acetal). The introduction of 13C‐labeling at either alkyne position in propynal utilized the Corey–Fuchs procedure for chain homologation.