cis-Selective cyclopropanations using chiral 5,5-diaryl bis(oxazoline) catalysts
作者:Karen Alexander、Stuart Cook、Colin L Gibson
DOI:10.1016/s0040-4039(00)01232-6
日期:2000.9
bis(oxazolines) have been prepared and used as ligands in the copper catalysed asymmetriccyclopropanation of styrene. Unusually, for bis(oxazolines), the diastereoselectivity of the process favoured the cis cyclopropanes with diastereomeric ratios of up to 65:35 being realised. The cis selectivity of the process was rationalised in terms of repulsion between the alkene substituent and the pro-R 5-aryl group