Nitrone Ylides: Two Possible 1,3‐Dipolar Cycloadditions but Only One Stepwise Formation of all‐<i>cis</i>‐5‐Aryl‐2,3,5‐trisubstituted <i>N</i>‐Hydroxypyrrolidines

Abstract

Abstract An efficient methodology for the synthesis of all‐ cis ‐ N ‐hydroxypyrrolidines has been developed through the formal [3+2] dipolar cycloaddition of electron‐poor alkenes and nitrone ylides generated from N ‐(methoxycarbonylmethyl)nitrones. Treatment of the nitrone with a tertiary amine in the presence of either a lithium salt or butyllithium followed by addition of the alkene at low temperature provided the product in very good chemical yield and excellent diastereoselectivity. Isolation and characterization of a key intermediate demonstrated that the reaction is a stepwise process consisting of an initial Michael addition followed by an intramolecular Mannich‐type reaction.