1,3-O- to -C-alkyl migration of 1-alkenyl alkyl acetals and ketals catalyzed by boron trifluoride. Selective cross- and regioselective aldol type reactions
1,3-Alkyl migration of 1-alkenyl alkyl acetals and ketals is effectively catalyzed by trifluoroborane etherate to give cross aldol type products selectively. Remarkable regio-selectivity is observed in the synthesis of α-alkyl-β-alkoxy-ketones.