Carbonylation of alkyltitanium compounds with allylic derivatives

Article abstract of DOI:10.1016/0022-328X(92)80021-O

Triisopropoxymethyltitanium (1a) or diisopropoxydimethyltitanium (1b) was treated with carbon monoxide (1 atm, balloon) at room temperature overnight (16-18 h), and then the reaction mixture was added to various allyl derivatives in the presence of palladium catalyst (5 molpercent based on the allylic derivatives) at room temperature.From 1b and cinnamyl acetate in the presence of tetrakis(triphenylphosphine)palladium, (E)-3,3-dimethyl-6-phenyl-5-hexen-2-one (5a) was afforded in 57percent yield.A similar reaction with trans-2-hexenyl acetate also gave the corresponding γ-δ-unsaturated ketone in 57percent yield.The formation of the products would be rationalized by titanium η²-acyl and oxicarbenoid intermediates.