Electrophilic activation involving phosphonium

Zhang, Y. Aguirre, S. A. Klumpp, D. A. Reactive, Dicationic Electrophiles Electrophilic Activation Involving the Phosphonium Group. Tetrahedron Lett. 2002, 43, 6837-6840. 

Phosphonium salt 28 was a very effective catalyst for the a-amination of a range of benzofuranones (Scheme 11.12) [53]. Mechanistically, the reaction, which is conducted under homogeneous conditions in the absence of any base is clearly distinct from phase-transfer catalysis. The authors propose a model that involves TT-TT interactions between the catalyst and the enolic form of the benzofuranone together with electrophilic activation of the diazo system by the phosphonium group. 

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