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Gold(I)-Catalyzed Enantioselective Synthesis of Benzopyrans via Rearrangement of Allylic Oxonium Intermediates

2009; American Chemical Society; Volume: 131; Issue: 10 Linguagem: Inglês

10.1021/ja900155x

1943-2984

Minoru Uemura, Iain D. G. Watson, Mikimoto Katsukawa, F. Dean Toste,

Synthetic Organic Chemistry Methods

The first transition metal catalyzed asymmetric carboalkoxylation reaction of propargyl esters is described. The (R)-MeO-DTBM-BIPHEP(AuCl)2-catalyzed reactions allow for the construction of benzopyrans containing quaternary stereocenters with excellent enantioselectivity. Experimental evidence supports a mechanism proceeding via the generation of a stabilized carbocation from an allylic oxonium intermediate and subsequent trapping by a chiral allylgold(I) spieces.