title: One-pot synthesis and chiral analysis of cyclopropane derivatives.
abstract: A user-friendly, one-pot procedure was developed to access racemic as well as enantiomerically enriched cyclopropanes. Thus, the cyclopropanation of olefin (3) was performed using Meldrum's acid (4) or dimethyl malonate (5) and diacetoxyiodobenzene PhI(OAc)2 (6) or iodosyl benzene PhI=O (7) for in situ generation and decomposition of the phenyliodonium ylide 1 and 2, respectively. The reaction proceeds well with 5 mol% of achiral rhodium (II)-catalyst [Rh2(OAc)4] and a 10-fold excess of olefin affording the cyclopropane derivates 10 and 11, respectively, with high yield. The system is compatible with chiral Rh(II)-catalysts 8 and 9 and an enantiomeric excess up to 66% was achieved. An effective baseline separation of the enantiomers of the resulting cyclopropane derivatives was achieved using gas chromatography on the chiral stationary phase Chirasil-beta-dex.
authors.affiliation: Department of Organic Chemistry, University of Geneva, Geneva, Switzerland. ashraf.ghanem@chiorg.unige.ch
authors.forename: Ashraf
authors.initials: A
authors.lastname: Ghanem
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Aboul-Enein
authors.forename: Paul
authors.initials: P
authors.lastname: Müller
mesh_terms: D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013237:Stereoisomerism
chemical_list: D003521:Cyclopropanes; C030797:cyclopropane