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[摘要]：In addition to a bifunctional Bronsted acid activation mode, an unconventional bifunctional mode of Lewis and Bronsted acid activations was revealed in a DFT study of bicyclic guanidine-catalyzed thio-Michael reaction. This activation mode provides an alternate reaction pathway for the C S bond forming step and influences the final stereochemical outcome. The calculated turnover frequencies of the R- and S-products, based on the energetic span model, are in good accord with the observed high stereoselectivity toward the S-product. |
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