Enantioconvergent iso-Pictet-Spengler Reactions: Organocatalytic Synthesis of Chiral Tetrahydro-γ-carbolines

Org Lett. 2023 Jul 21;25(28):5248-5252. doi: 10.1021/acs.orglett.3c01723. Epub 2023 Jul 6.

Abstract

Enantioconvergent iso-Pictet-Spengler reactions of chiral racemic ß-formyl esters and a ß-keto ester are reported, providing complex tetrahydro-γ-carbolines containing two contiguous stereocenters. The reactions are catalyzed by a chiral thiourea and benzoic acid cocatalytic system and constitute rare cases of nonhydrogenative stereoconvergent additions to racemic α-stereogenic-ß-dicarbonyls. Elaboration of the products to chiral aminoalcohols and carbamates is demonstrated.