title: Stereoselective Rh2(S-IBAZ)4-catalyzed cyclopropanation of alkenes, alkynes, and allenes: asymmetric synthesis of diacceptor cyclopropylphosphonates and alkylidenecyclopropanes.
abstract: A mild and highly stereoselective rhodium(II)-catalyzed cyclopropanation of alkenes, alkynes, and allenes with diacceptor diazo compounds is reported. Using the phosphonate moiety as an efficient trans-directing group, the first catalytic asymmetric route to diacceptor cycloprop(en)ylphosphonates was developed by employing an α-cyano diazophosphonate and Rh(2)(S-IBAZ)(4) as chiral catalyst. The isosteric character of phosphonic and carboxylic acid derivatives allowed the alternative use of an α-cyano diazo ester in the process, leading to α-cyano cycloprop(en)ylcarboxylates in high yields and stereoselectivities. Taking advantage of the particular reactivity of the cyanocarbene intermediates involved in this system, the scope of compatible substrates could be extended to substituted allenes, leading to the development of the first catalytic enantioselective method for the synthesis of diacceptor alkylidenecyclopropanes.
authors.affiliation: Centre in Green Chemistry and Catalysis, Department of Chemistry, Université de Montréal, P.O. Box 6128, Station Downtown, Montréal, Québec, Canada H3C 3J7.
authors.forename: Vincent N G
authors.initials: VN
authors.lastname: Lindsay
authors.forename: Dominic
authors.initials: D
authors.lastname: Fiset
authors.forename: Philipp J
authors.initials: PJ
authors.lastname: Gritsch
authors.forename: Soula
authors.initials: S
authors.lastname: Azzi
authors.forename: André B
authors.initials: AB
authors.lastname: Charette
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D000480:Alkynes; D003521:Cyclopropanes; D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; D012238:Rhodium