Aryl- and Alkynyltri-isopropoxytitanium Reagents in Regioselective Carbon-Carbon Bond Formation in Azines

Article abstract of DOI:10.1016/0040-4020(92)80015-8

Regioselective arylation in the 4-position in pyridines results from 1:1-adduct formation between an aryltriisopropoxytitanium reagent and N-isobutyloxycarbonyl- or an N-silyloxymethyl-3-cyanopyridinium salt after successive DDQ dehydrogenation and cleavage of the 1-substituent.Complete regioselectivity for new C-C bond formation in the 4-position results in the adduct formation between aryl- and phenylethynyltri-isopropoxytitanium reagents and pyrimidin-2(1H)-ones; with ethynyltriisopropoxytitanium the new C-C bond formation occurs at the 6-position.