Enantioselective Formal [3+2] Cycloaddition of Epoxides with Imines under Brønsted Base Catalysis: Synthesis of 1,3‐Oxazolidines with Quaternary Stereogenic Center |
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Authors: | Dr. Azusa Kondoh Shiori Akahira Masafumi Oishi Prof. Dr. Masahiro Terada |
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Affiliation: | 1. Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, Sendai, Japan;2. Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan |
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Abstract: | The formal [3+2] cycloaddition of epoxides and unsaturated compounds is a powerful methodology for the synthesis of densely functionalized five‐membered heterocyclic compounds containing oxygen. Described is a novel enantioselective formal [3+2] cycloaddition of epoxides under Brønsted base catalysis. The bis(guanidino)iminophosphorane as a chiral organosuperbase catalyst enabled the enantioselective reaction of β,γ‐epoxysulfones with imines, owing to its strong basicity and high stereocontrolling ability, to provide enantioenriched 1,3‐oxazolidines having two stereogenic centers, including a quaternary one, in a highly diastereo‐ and enantioselective manner. |
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Keywords: | asymmetric catalysis Brø nsted base cycloaddition heterocycles organocatalysis |
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