Microwave-assisted reactions of α-diazosulfoxides to form α-oxosulfines

Wolff rearrangement of α-diazosulfoxides has been induced by microwave irradiation forming α-oxosulfines. The outcome of the transformation was similar to the outcome under thermal conditions, with no evidence of specific microwave effects. Critically, this methodology allows generation of these synthetically useful α-oxosulfines in the absence of a transition-metal catalyst. Confirmation of the stereochemistry of the α;-oxosulfines was undertaken by trapping as Diels-Alder cycloadducts indicating that the (Z)-oxosulfines are the kinetic products but rearrange to the thermodynamically favoured (E)-oxosulfines in the absence of a diene trap during their formation.