Trio Catalysis Merging Enamine,Brønsted Acid,and Metal Lewis Acid Catalysis: Asymmetric Three‐Component Aza‐Diels–Alder Reaction of Substituted Cinnamaldehydes,Cyclic Ketones,and Arylamines |
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Authors: | Dr Yongming Deng Siddhartha Kumar Prof Kraig Wheeler Prof Hong Wang |
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Institution: | 1. Department of Chemistry and Biochemistry, Miami University, 701 E High Street, Oxford, OH 45056 (USA);2. Department of Chemistry, Eastern Illinois University, 600 Lincoln Ave., Charleston, IL 61920 (USA) |
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Abstract: | A trio catalyst system, composed of arylamine, BINOL‐derived phosphoric acid, and Y(OTf)3, enables the combination of enamine catalysis with both hard metal Lewis acid catalysis and Brønsted acid catalysis for the first time. Using this catalyst system, a three‐component aza‐Diels–Alder reaction of substituted cinnamaldehyde, cyclic ketone, and arylamine is carried out with high chemo‐ and enantioselectivity, affording a series of optically active 1,4‐dihydropyridine (DHP) derivatives are obtained in 91–99 % ee and 59–84 % yield. DHPs bearing a chiral quaternary carbon center are also obtained with good enantioselectivity and moderate yield (three examples). Preliminary mechanistic investigations have also been conducted. |
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Keywords: | asymmetric catalysis cooperative catalysis heterocycles multicomponent reactions synthetic methods |
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