Enantioselective total synthesis of (+)-lysergic acid, (+)-lysergol, and (+)-isolysergol by palladium-catalyzed domino cyclization of allenes bearing amino and bromoindolyl groups

J Org Chem. 2011 Apr 1;76(7):2072-83. doi: 10.1021/jo102388e. Epub 2011 Mar 1.

Abstract

Enantioselective total synthesis of the biologically important indole alkaloids (+)-lysergol, (+)-isolysergol, and (+)-lysergic acid is described. Key features of these total synthesis include (1) a facile synthesis of a chiral 1,3-amino alcohol via the Pd(0)- and In(I)-mediated reductive coupling reaction between L-serine-derived 2-ethynylaziridine and formaldehyde; (2) the Cr(II)/Ni(0)-mediated Nozaki-Hiyama-Kishi (NHK) reaction of an indole-3-acetaldehyde with iodoalkyne; and (3) Pd(0)-catalyzed domino cyclization of an allene bearing amino and bromoindolyl groups. This domino cyclization enabled direct construction of the C/D ring system of the ergot alkaloids skeleton, as well as the creation of the C5 stereogenic center with transfer of the allenic axial chirality to the central chirality.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Cyclization
  • Ergolines / chemical synthesis*
  • Ergolines / chemistry
  • Ergot Alkaloids / chemical synthesis*
  • Ergot Alkaloids / chemistry*
  • Indoles / chemistry*
  • Lysergic Acid / chemical synthesis*
  • Lysergic Acid / chemistry
  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Palladium / chemistry*
  • Stereoisomerism

Substances

  • Ergolines
  • Ergot Alkaloids
  • Indoles
  • Palladium
  • Lysergic Acid
  • lysergol