Construction of C–C bonds via alkoxy radical-mediated remote C(sp3)–H functionalization is largely unexplored, as it is a formidable challenge to directly generate alkoxy radicals from alcohols due to the high bond dissociation energy (BDE) of O–H bonds. Disclosed herein is a practical and elusive metal-free alcohol-directed heteroarylation of remote unactivated C(sp3)–H bonds. Phenyliodine bis(trifluoroacetate) (PIFA) is used as the only reagent to enable the coupling of alcohols and heteroaryls. Alkoxy radicals are readily generated from free alcohols under the irradiation of visible light, which trigger the regioselective hydrogen-atom transfer (HAT). A wide range of functional groups are compatible with the mild reaction conditions. Two unactivated C–H bonds are cleaved and one new C–C bond is constructed during the reaction. This protocol provides an efficient strategy for the late-stage functionalization of alcohols and heteroaryls.
Herein we describe an efficient distal
ipso-migration of O- and S-containing
heteroaryls and the
radical heteroarylation of unactivated alkenes. The migration is triggered
by various fluoroalkyl radicals, leading to valuable multifunctionalized
ketones. The comparisons of migratory aptitude for O-/S-containing heteroaryls are comprehensively investigated.
The origin of the chemoselective migration could be partially attributed
to the discrepancy in the energy level of the LUMO of each heteroaryl
group.
A new protocol for the elusive cyanotrifluoromethylthiolation of unactivated olefins is described. A broad range of vicinal CF3S‐substituted alkyl nitriles are furnished in good yields under mild reaction conditions. The intramolecular cyano migration strategy is harnessed for the trifluoromethylthiolation of alkenes for the first time, thus offering an efficient tool for the construction of alkyl trifluoromethylthioethers.magnified image
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