Highly regioselective dipolar cycloadditions of nitrile oxides with α,β-acetylenic aldehydes

Synthesis of N-, O-, and S-heterocycles from aryl/alkyl alkynyl aldehydes

“…Both alkynyl aldehydes 1a and oximes 58a bearing aryl, heteroaryl and alkyl groups were compatible in this transformation ( Scheme 80 ). 94 Preparation and cytotoxic evaluation of isoxazoles 59b and pyrazoles 59d were performed by Praveen et al ( Scheme 81 ). 95 In this regard, they investigated the capability of AuCl 3 in the cycloisomerization of α,β-acetylenic oximes 59a and α,β-acetylenic hydrazones 59c.…”