SEARCH

SEARCH BY CITATION

Keywords:

  • asymmetric catalysis;
  • bifunctional thioureas;
  • gold;
  • one-pot processes;
  • organocatalysis

Abstract

A direct asymmetric one-pot synthesis of optically active 2,3-dihydropyrroles from propargylated malononitrile and N-Boc-protected (Boc=tert-butoxycarbonyl) imines is presented. The approach is based on a bifunctional organocatalytic Mannich-type reaction and a subsequent gold-catalyzed alkyne hydroamination and isomerization. The compatibility of both catalytic systems is presented and the overall transformation results in good yields (up to 70 %) with high selectivities (endo/exo>10:1) and enantioselectivities (up to 88 % ee). The absolute configuration of the final products is unambiguously established by X-ray analysis. To highlight the synthetic potential of the accessed heterocyclic compounds, their transformation into 1-pyrrolines, which represent direct precursors of pyrrolidines, is presented.