C2-ketonylation of carbohydrates via excited-state palladium-catalyzed 1,2-spin-center shift |
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| Authors: | Gaoyuan Zhao Upasana Mukherjee Lin Zhou Yue Wu Wang Yao Jaclyn N Mauro Peng Liu Ming-Yu Ngai |
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| Institution: | Department of Chemistry, Institute of Chemical Biology and Drug Discovery, The State University of New York at Stony Brook, Stony Brook, New York 11794 USA.; Department of Chemistry, Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh Pennsylvania 15260 USA, |
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| Abstract: | C2-ketonyl-2-deoxysugars, sugars with the C2-hydroxyl group replaced by a ketone side chain, are important carbohydrate mimetics in glycobiology and drug discovery studies; however, their preparation remains a vital challenge in organic synthesis. Here we report the first direct strategy to synthesize this class of glycomimetics from readily available 1-bromosugars and silyl enol ethers via an excited-state palladium-catalyzed 1,2-spin-center shift (SCS) process. This step-economic reaction features broad substrate scope, has a high functional group tolerance, and can be used in late-stage functionalization of natural product- and drug-glycoconjugates. Preliminary experimental and computational mechanistic studies suggested a non-chain radical mechanism involving photoexcited palladium species, a 1,2-SCS process, and a radical Mizoroki–Heck reaction.The excited-state palladium-catalyzed 1,2-spin-center shift process streamlines the synthesis of C2-ketonyl sugars. This step-economic reaction has a broad scope and allows late-stage functionalization of natural product- and drug-glycoconjugates. |
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