Gold carbenoids cycloisomerization

The solvent effect on the regioselectivity of the AuCls-catalyzed cycloisomerization of a bromoallenyl ketone was evaluated by density functional theory calculations. Upon the generation of the gold carbenoid intermediate from cyclization of the aUene precursor, the tetrahydrofiiran solvent can act as a proton shuttle to assist the 1,2-H migration to afford the 2-bromofuran product (14S2149). 

As previously stated with Pt catalysts, the cycloisomerization involves an intramolecular cyclopropanation to give a cyclopropyl gold-carbenoid species, which is followed by a 1,2-// shift. Interestingly, in the presence of a quaternary center on the propargylic position in 55, a 1,2-alkyl shift is observed, allowing a... 

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