Construction of stereogenic center beta to the N-Pyrrolidinyl moiety via diastereoselective reactions of tricyclic lactones and the synthesis of (−)-Indolizidine 195G

The Enolates of hexahydro-3,4-dioxa-8a-aza-as-indacen-2-ones can react with electrophiles in a substrate-controlled fashion to create a new stereogenic center positioned beta to the N-pyrrolidinyl moiety. Preferential diastereoselective reactions predominantly proceeded from the convex face of the enolates, yielding stereospecific alkylated or halo-substituted products with high yields and exceptional diastereoselectivities. Di-substituted compounds were obtained by the alkylation or halogenation of the enolates of the corresponding mono-substituted compounds. Total synthesis of (−)-indolizidine 195G was also accomplished. © 2024 Elsevier Science. All rights reserved. [Display omitted]