involve chlororhodation to the alkynes by the intermediary arylchlororhodium(III) species generated in situ followed by reductive elimination of the products, which are suggested by the results of some control experiments. In contrast to the reaction with terminal alkynes, that with some internal ones proceeds without decarbonylation to produce 2,3-disubstituted-1-indenones as the predominant products.
An efficient, novel and direct access to 1-halo-1,3-butadienes is developed. This stereoselective ruthenium-catalysed reaction proceeds under mild conditions via the head-to-head oxidative coupling of two alkynes and a concomitant hydrohalogenation.