Synthesis of Diarylacetylenes Bearing Electron-Withdrawing Groups via the Smiles Rearrangement

Nitrobenzyl benzothiazol-2-yl sulfones and nitrobenzyl 1-phenyl-1 H-tetrazol-5-yl sulfones react with chlorides of aromatic acids to form beta-acyl derivatives. These products undergo the Smiles rearrangement resulting in the formation of the corresponding nitrophenyl arylacetylenes in 50-60% overall yields (approx. 75% per step). Sulfones bearing CF3 or CN groups instead of a NO2 substituent form mixtures of the acetylenes in moderate yields and benzyl aryl ketones in yields above 40%.