Sonogashira Cross-Coupling of Arenediazonium Salts

An efficient cross-coupling of terminal alkynes with arenediazonium salts has been developed. To the best of our knowledge, this transformation is the first example of the alkynylation of arenediazonium salts. The reaction occurs under mild conditions in the presence of nBu4NI and proceeds through a domino iododediazoniation/Sonogashira cross-coupling sequence. Good to excellent yields are usually obtained. A variety of alkyl, aryl, and heteroaryl substituentson the alkyne substrate can be used and many useful functionalities including bromo, chloro, keto, ester, ether, cyano, and nitro substituents on the arenediazonium salt are also tolerated. ortho Substituents, both in the arenediazonium salt and the alkynylarene, are also tolerated. The formation of alkynylarenes bearing 2-chloro-, 2-bromo-, 2-amino-, and 2- hydroxyaryl moieties may be exceedingly useful for appending heterocyclic rings to aniline fragments. The entire arenediazonium salt synthesis/iododediazoniation/cross-coupling sequence can also be performed as a one-pot domino process, omitting the isolation of the arenediazonium salt.