Dipolarophile‐Steered Formal Stereodivergent Synthesis of 2,5‐<i>cis</i>/<i>trans</i>‐Pyrrolidines Based on Asymmetric 1,3‐Dipolar Cycloaddition of Imino Lactones
The formal diastereodivergent asymmetricsynthesis of 2,5-cis/trans pyrrolidines was achieved by using a different type of activated alkenes. The silver complex-catalyzed asymmetric 1,3-dipolar cycloaddition of imino lactones with ylidene-isoxazolones, and subsequent transformation afforded chiral pyrrolidines with 2,5-trans diastereoselectivity. In contrast, 2,5-cis substituted pyrrolidines were obtained