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Keywords:

  • azirine;
  • gold;
  • heterocycles;
  • homogeneous catalysis;
  • pyridine

Abstract

2H-Azirines are easily synthesized from the corresponding ketones and, despite possessing a C[DOUBLE BOND]N bond embedded in a strained three-membered cycle, they are sufficiently stable to be isolated, stored, and manipulated. 2H-Azirines can be regarded as valuable synthetic equivalents of alkenyl nitrenes, however, reactions capitalizing on the cyclic strain of the heterocyclic motif and involving the cleavage of the C[BOND]N single bond remain surprisingly limited. A gold-catalyzed reaction that allows the formation of polysubstituted functionalized pyridines from easily accessible 2-propargyl 2H-azirine derivatives was developed. This transformation, which corresponds to an unprecedented intramolecular transfer of an alkenyl nitrene to an alkyne, proceeds with low catalyst loading, is efficient, and exhibits a high functional-group tolerance and a wide substrate scope.