Preview

PDF Not available 191Kb

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--dex.

Item Type:	Refereed Article
Keywords:	asymmetric catalysis • carbene • chirasil--Dex • cyclopropane • enantiomeric excess • enantioselective gas chromatography • rhodium complexes • ylide
Research Division:	Chemical Sciences
Research Group:	Organic Chemistry
Research Field:	Organic Chemical Synthesis
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Chemical Sciences
Author:	Ghanem, A (Dr Ashraf Ghanem)
ID Code:	58297
Year Published:	2005
Web of Science® Times Cited:	27
Deposited By:	Austn Centre for Research in Separation Science
Deposited On:	2009-09-25
Last Modified:	2009-09-25
Downloads:	0