title: A Mixed-Ligand Chiral Rhodium(II) Catalyst Enables the Enantioselective Total Synthesis of Piperarborenine B.
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.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Panish
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
authors.forename: Srinivasa R
authors.initials: SR
authors.lastname: Chintala
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA. jmfox@udel.edu.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Fox
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D010881:Piperidones / Q000138:chemical synthesis*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D010881:Piperidones; C570724:piperarborenine B; D012238:Rhodium
keywords: bicyclobutane; chiral rhodium catalyst; homoconjugate addition; piperarborenine B; strained molecules