title: Asymmetric Rh(II)-catalyzed cyclopropanation of alkenes with diacceptor diazo compounds: p-methoxyphenyl ketone as a general stereoselectivity controlling group.
abstract: Different diacceptor diazo compounds bearing an α-PMP-ketone group were found to be effective carbene precursors for the highly stereoselective Rh(2)(S-TCPTTL)(4)-catalyzed cyclopropanation of alkenes (EWG = NO(2), CN, CO(2)Me). The resulting products were readily transformed into a variety of biologically relevant enantiopure molecules, such as cyclopropane α- and β-amino acid derivatives. Different mechanistic studies carried out led to a rationale for the high diastereo- and enantioselectivity obtained, where the PMP-ketone moiety was found to play a critical role in the stereoinduction process. Additionally, the use of catalytic amounts of achiral Lewis bases to influence the enantioinduction of the reactions developed is documented.
authors.affiliation: 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: Cyril
authors.initials: C
authors.lastname: Nicolas
authors.forename: André B
authors.initials: AB
authors.lastname: Charette
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D001388:Aziridines / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D003521:Cyclopropanes / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D000475:Alkenes; D001388:Aziridines; D001391:Azo Compounds; D003521:Cyclopropanes; D007659:Ketones; C033132:aziridine; C030797:cyclopropane; D012238:Rhodium