Catalytic Asymmetric Alkynylation of 3,4‐Dihydro‐β‐carbolinium Ions Enables Collective Total Syntheses of Indole Alkaloids
Lixin Liang, Shiqiang Zhou, Wei Zhang, Rongbiao Tong
Abstract
Chiral tetrahydro-β-carboline (THβC) is not only a prevailing structural feature of many natural alkaloids but also a versatile synthetic precursor for a vast array of monoterpenoid indole alkaloids. Asymmetric synthesis of C1-alkynyl THβCs remains rarely explored and challenging. Herein, we describe the development of two complementary approaches for the catalytic asymmetric alkynylation of 3,4-dihydro-β-carbolinium ions with up to 96 % yield and 99 % ee. The utility of chiral C1-alkynyl THβCs was demonstrated by the collective total syntheses of seven indole alkaloids: harmicine, eburnamonine, desethyleburnamonine, larutensine, geissoschizol, geissochizine, and akuammicine.
Topics & Concepts
Indole testAlkynylationEnantioselective synthesisChemistryCatalysisYield (engineering)StereochemistryCombinatorial chemistryOrganic chemistryMaterials scienceMetallurgyAlkaloids: synthesis and pharmacologyChemical synthesis and alkaloidsSynthesis and bioactivity of alkaloids