Phosphine-Catalyzed [3 + 2] Cycloaddition of 4,4-Dicyano-2-methylenebut-3-enoates with Benzyl Buta-2,3-dienoate and Penta-3,4-dien-2-one
摘要:
4,4-Dicyano-2-methylenebut-3-enoates are employed in the phosphine-catalyzed [3 + 2] cycloaddition with allenoates for the first time, affording regiospecific [3 + 2]-annulation products in moderate to good yields. The multifunctional chiral thiourea-phosphines having an axially chiral binaphthyl scaffold are effective catalysts for the asymmetric variant of this reaction, giving the alpha-regioisomers in good yields and moderate enantioselectivities.