Radical-Mediated 1,3,4-Trifunctionalzaition Cascades of 1,3-Enynes with Sulfinates and tert-Butyl Nitrite: Facile Access to Sulfonyl Isoxazoles

An unprecedented indium-promoted three-component 1,3,4-trifunctionalization cascades of 1,3-enynes with sodium sulfinates and tert-butyl nitrite (TBN) for accessing 5-sulfonylisoxazoles involving [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, including C-S, C-N and C-O bonds, in a single reaction through a sequence of sulfonylatyion, isomerization, nitration and annulation with broad substrate scope, excellent selectivity and the potential of late stage functionalization of natural products.