Chiral phosphine oxide sequentially activates silicon tetrachloride and trichlorosilyl enol ethers to facilitate asymmetric aldol/vinylogous aldol reaction of 4-methoxy-3-penten-2-one and conjugated aldehydes in a highly enantioselective fashion, and the subsequent cyclization produced optically active 2,6-disubstituted 2,3-dihydro-4-pyranones bearing stereogenic centers at a remote position in a single operation.
Keywords: asymmetric catalysis; phosphine oxide; pyranone; remote-control; tandem reaction.