Cooperative Photocatalysis of 9,10-Phenanthrenequinone and Sn(OTf)2 for Direct Mannich Reaction of Ethers via Hydrogen Atom Transfer Pathway

초록

A dual photocatalytic system combining 9,10-phenanthrenequinone (o-PQ) and Sn(OTf)2 enabled the visible light-induced Mannich-type addition of ethers to nitrones via direct Csp3-H activation. This oxidant- and reductant-free method featured broad substrate scope, good yields, and excellent functional group tolerance. Gram-scale synthesis and downstream transformations (Suzuki, Sonogashira, Heck) demonstrated its synthetic utility. Mechanistic studies suggested a cooperative cycle where a photoexcited o-PQ-Sn(II) complex mediated hydrogen atom transfer, generating alpha-oxy radicals that reacted with Sn(II)-activated nitrones.

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