Annulative Aminosulfonylation of Unactivated Alkenes for Accessing Pyrazolines via Multicomponent SO Insertion.

A direct arylsulfonylation of β,γ-unsaturated hydrazones method, in which sulfonated pyrazolines are accessed by a three-component reaction of β,γ-unsaturated hydrazones, DABSO, and aryldiazonium tetrafluoroborates, has been developed without external oxidants or catalysts. This transformation is triggered by the formation of arylsulfonyl radicals in situ from the reaction of aryldiazonium tetrafluoroborates and DABSO, and is enabled by controllable generation of C center radical, in which DABSO was utilized as the sulfone source and an oxidant in this radical-mediated cascaded reaction. A wide range of substrates can be applied in this process to afford pyrazolines in good yield, and it is amenable for gram-scale synthesis.

Visible-light-catalyzed synthesis of 1,3-benzoxazines formal [4 + 2] cycloaddition of oximes with -hydroxybenzyl alcohols.

A formal [4 + 2] cycloaddition of oximes with -hydroxybenzyl alcohols was developed to easily synthesize diverse 1,3-benzoxazine derivatives. This synthesis was achieved under visible light-based organocatalytic and TsOH conditions. The reaction proceeds through the photoisomerization of oximes visible light-mediated energy transfer, followed by the nucleophilic attack of -QMs to oximes as a 1,2-dipole synthon, cyclization, and isomerization.