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

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 α-regioisomers
in good yields and moderate enantioselectivities.