Enantioselective [3 + 2] cycloadditions of terminal allenoates with β-sulfonyl-α,β-unsaturated ketones

A highly efficient and mild method for [3 ​+ ​2] cycloaddition of β-sulfonyl-α,β-unsaturated ketones with terminal allenoates was well-explored and developed. The reactions were successfully performed by applying multifunctional chiral phosphine P6 which was screened from eight chiral phosphorus reagents to finally result in a variety of enantioenriched sulfone-substituted cyclopentenes with two chiral centers (up to 81% yield with 94% ee). Moreover, 2.5 ​mol% catalytic equivalents were proved to be feasible when this reaction was performed on a 10 ​mmol scale.