Highly enantio-, regio- and diastereo-selective one-pot [2+3]-cycloaddition reaction via isomerization of 3-butynoates to allenoates

Phosphine-catalyzed one-pot isomerization and [2 + 3]-cycloaddition of 3-butynoates with electron-deficient olefins affords highly functionalized cyclopentenes with both good yields and excellent selectivities of up to 99%.