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Direct Enantio- and Diastereoselective Vinylogous Addition of Butenolides to Chromones Catalyzed by Zn-ProPhenol
- Trost, Barry M., Gnanamani, Elumalai, Kalnmals, Christopher A., Hung, Chao-I “Joey”, Tracy, Jacob S.
- Journal of the American Chemical Society 2019 v.141 no.4 pp. 1489-1493
- Lewis acids, Lewis bases, catalysts, diastereoselectivity, enantioselectivity, quinolones
- We report the first enantio- and diastereoselective 1,4-addition of butenolides to chromones. Both α,β- and β,γ-butenolide nucleophiles are compatible with the Zn-ProPhenol catalyst, and preactivation as the siloxyfurans is not required. The scope of electrophiles includes a variety of substituted chromones, as well as a thiochromone and a quinolone, and the resulting vinylogous addition products are generated in good yield (31 to 98%), diastereo- (3:1 to >30:1), and enantioselectivity (90:10 to 99:1 er). These Michael adducts allow rapid access to several natural product analogs, and can be easily transformed into a variety of other interesting scaffolds as well.