Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 12. Extrusion of Ph₃P from sulfonyl ylides and reactivity of the resulting sulfonyl carbenes

Twelve sulfonyl stabilised phosphorus ylides have been prepared and their behaviour upon flash vacuum pyrolysis at 600 degrees C has been examined. Examples with an arylsulfonyl substituent undergo loss of Ph3PO to give intractable products but those with an arylmethylsulfonyl substituent separately lose Ph3P and SO2 to give products consistent with the intermediacy of sulfonyl carbenes. X-Ray structure determinations of one ylide from each series show a more significant P-O non-bonding interaction in the first case, providing some explanation for the different thermal reactivity.