A Mixed‐Ligand Chiral Rhodium(II) Catalyst Enables the Enantioselective Total Synthesis of Piperarborenine B |
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| Authors: | Robert A Panish Srinivasa R Chintala Prof Joseph M Fox |
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| Institution: | Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA |
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| Abstract: | A novel, mixed‐ligand chiral rhodium(II) catalyst, Rh2(S‐NTTL)3(dCPA), has enabled the first enantioselective total synthesis of the natural product piperarborenine B. A crystal structure of Rh2(S‐NTTL)3(dCPA) reveals a “chiral crown” conformation with a bulky dicyclohexylphenyl acetate ligand and three N‐naphthalimido groups oriented on the same face of the catalyst. The natural product was prepared on large scale using rhodium‐catalyzed bicyclobutanation/ copper‐catalyzed homoconjugate addition chemistry in the key step. The route proceeds in ten steps with an 8 % overall yield and 92 % ee. |
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| Keywords: | bicyclobutane chiral rhodium catalyst homoconjugate addition piperarborenine B strained molecules |
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