Gold(I)-catalyzed enantioselective synthesis of benzopyrans via rearrangement of allylic oxonium intermediates.
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.
Uemura
Minoru
M
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Watson
Iain D G
ID
Katsukawa
Mikimoto
M
Toste
F Dean
FD
D001578:Benzopyrans / Q000737:chemistry*; D002384:Catalysis; D006046:Gold / Q000737:chemistry*; D013237:Stereoisomerism
D001578:Benzopyrans; D006046:Gold