Isoxazoles (Problem 36) have taken on increased significance as synthetic targets, because they are found in the structures of some recently discovered naturally occurring molecules that show promise as antibiotics (see Chemical Highlight 20-2). Isoxazoles may be prepared by reaction of alkynes with compounds containing the unusual nitrile oxide functional group: 

Suggest a mechanism for this process. 

Problem 36

Transcribed Image Text:

+ R RC=CR + R'C=N-O:- Nitrile oxide R R Isoxazole