A convenient gram-scale method for the preparation of 2-halo-2 H -azirine-2-carboxylic acid esters, thioesters and amides via metal-catalyzed isomerization of 5-heteroatom-substituted 4-haloisoxazoles is developed. The formation of the esters and amides is efficiently catalyzed by Rh 2 (Piv) 4, while FeCl 2 ·4H 2 O is the catalyst of choice for the synthesis of the thioesters. In addition, rhodium catalysis is successfully applied in the synthesis of azirine-2-carboxylates from non-halogenated 5-alkoxyisoxazoles.
Scopus subject areas
- Organic Chemistry