CARBOMETALATION METHANE ELIMINATION-REACTIONS OF DIMETHYLTITANOCENE - FORMATION OF TITANOCENE VINYL COMPLEXES AND TITANACYCLOBUTENES

Dimethyltitanocene reacts with diphenylacetylene to afford the vinyl complex resulting from insertion of the alkyne into one of the titanium-methyl bonds. Thermolysis of this vinyl complex results in extrusion of methane and formation of the titanacyclobutene. Other alkynes similarly afford the corresponding titanacyclobutenes. In contrast, nitriles react with dimethyltitanocene to afford not azatitanacyclobutenes but rather diazatitanacyclohexadienes, incorporating 2 equiv of the nitrile.