A radical-mediated 1,3,4-trifunctionalization cascade of 1,3-enynes with sulfinates andtert-butyl nitrite: facile access to sulfonyl isoxazoles

An unprecedented indium-promoted three-component 1,3,4-trifunctionalization cascade of 1,3-enynes with sodium sulfinates and tert-butyl nitrite (TBN) to access 5-sulfonylisoxazoles via [3+2] annulation is reported. By employing TBN as both the radical initiator and the N-O two atom unit, this method enables the formation of three new carbon-heteroatom bonds, C-S, C-N and C-O bonds, in a single reaction through a sequence of sulfonylation, isomerization, nitration and annulation with a broad substrate scope, excellent selectivity and the potential of late-stage functionalization of natural products.