title: Highly cis-selective Rh(I)-catalyzed cyclopropanation reactions.
abstract: The performance of recently reported highly cis-diastereoselective Rh(I) cyclopropanation catalysts has been significantly improved by a systematic study of different reaction parameters (catalyst activation, solvent, temperature, stoichiometry). The catalyst efficiency and diastereoselectivity were enhanced by changing the activating agent from AgOTf to NaBArf. With this new system, the Rh(I) catalyst was shown to be a highly efficient and cis-diastereoselective cyclopropanation catalyst in reactions between α-diazoacetates and a range of different alkenes and substituted derivatives. Particularly noteworthy is the remarkable reactivity and cis-diastereoselectivity displayed in the reactions between ethyl diazoacetate and cyclopentene, 2,5-dihydrofuran, and benzofuran, with yields up to 99% and cis-selectivities greater than 99%.
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, Norway.
authors.forename: Marianne Lenes
authors.initials: ML
authors.lastname: Rosenberg
authors.forename: Klára
authors.initials: K
authors.lastname: Vlašaná
authors.forename: Nalinava
authors.initials: N
authors.lastname: Sen Gupta
authors.forename: David
authors.initials: D
authors.lastname: Wragg
authors.forename: Mats
authors.initials: M
authors.lastname: Tilset
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000138:chemical synthesis; D000970:Antineoplastic Agents / Q000138:chemical synthesis; D001572:Benzofurans / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003517:Cyclopentanes / Q000737:chemistry*; D003521:Cyclopropanes / Q000138:chemical synthesis*; D003979:Diazonium Compounds / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D012238:Rhodium / Q000737:chemistry; D012997:Solvents; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D000475:Alkenes; D000890:Anti-Infective Agents; D000970:Antineoplastic Agents; D001572:Benzofurans; D003517:Cyclopentanes; D003521:Cyclopropanes; D003979:Diazonium Compounds; D012997:Solvents; D012238:Rhodium; C105430:benzofuran; C032111:diazoacetic ester