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 ...