A Dramatic Substituent Effect in Silver(I) -Catalyzed Regioselective Cyclization of ortho-Alkynylaryl Aldehyde Oxime Derivatives

A dramatic substituent effect was found in the silver(I)-catalyzed cyclization reaction of ortho-alkynylaryl aldehyde oxime derivatives. When R is an alkyl group, the Ag(I)-catalyzed reaction in dimethylacetamide at 110 degrees C (conditions A) affords isoquinolines in good to excellent yields, in contrast, isoquinolin-1(2H)-ones were produced in moderate to high yields under conditions B (dimethylformamide, room temperature) when R is an acetyl group. A plausible mechanism was proposed for this product selectivity control reaction (PSCR) by subtle structure modification.