Premium
Total Syntheses of Pyroclavine, Festuclavine, Lysergol, and Isolysergol via a Catalytic Asymmetric Nitro‐Michael Reaction
Author(s) -
Bhunia Subhajit,
Chaudhuri Saikat,
Bisai Alakesh
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201702459
Subject(s) - enantioselective synthesis , nitronate , michael reaction , stereocenter , intramolecular force , thiourea , nitro , total synthesis , chemistry , catalysis , stereochemistry , nitroaldol reaction , conjugated system , vicinal , organic chemistry , alkyl , polymer
A catalytic enantioselective construction of vicinal stereocenters is reported. The reaction takes advantage of thiourea‐catalyzed intramolecular nitronate addition onto α,β‐unsaturated ester to afford exceptional levels of enantioselectivity (up to 97 % ee ) with moderate diastereoselectivity (up to 4:1). Using this method, a cross‐conjugated ester was synthesized in few steps, from which a 6‐ endo ‐ trig cyclisation led to the formation of all required functionalities for total syntheses of ergot alkaloids. The strategy not only offers first total syntheses of ergot alkaloids, festuclavine ( 1 c ), and pyroclavine ( 1 e ), and but also an efficient and general approach to other congeners such as, lysergol ( 1 b ), and isolysergol ( 1 d ).