Gold-catalyzed synthesis of functionalized pyridines by using 2H-azirines as synthetic equivalents of alkenyl nitrenes.
2H-Azirines are easily synthesized from the corresponding ketones and, despite possessing a C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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.
Département de Chimie, UMR 7652 and 7653 CNRS, Ecole Polytechnique, 91128 Palaiseau (France).
Agnes
A
Prechter
Guilhem
G
Henrion
Pierre
P
Faudot dit Bel
Fabien
F
Gagosz
azirine; gold; heterocycles; homogeneous catalysis; pyridine