Convenient Synthesis of Isoxazoles

Significance

A new route to substituted isoxazoles 3 involving an electrophile-induced cyclization of acetylenic O -methyl oximes 2 is reported. The reactions proceed with iodo-, bromo-, and seleno-electrophiles in good yields (55% to quant.) under mild conditions. A major advantage of the methodology is the availability of the starting materials 1 by Sonogashira coupling of readily available carboxylic acid chlorides with acetylenes.