A study of 4-substituted 5,5-diaryl oxazolidin-2-ones as efficacious chiral auxiliaries
作者:Colin L. Gibson、Karen Gillon、Stuart Cook
DOI:10.1016/s0040-4039(98)01412-9
日期:1998.9
A series of three 5,5-diaryl substituted oxazolidin-2-ones (diphenyl, dinaphthyl and ditolyl) have been prepared and shown to be particularly effective chiral auxiliaries to afford high yields and diastereoselectivities for alkylation and azidations of their N-acyl derivatives. The 5,5-ditolyl oxazolidin-2-one proved to be particularly efficacious in terms of diastereoselectivity, yield and solubility
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
Highly effective and recyclable chiral auxiliaries: a study of the synthesis and use of three 4-isopropyl-5,5-diaryloxazolidin-2-ones
作者:Karen Alexander (née Gillon)、Stuart Cook、Colin L. Gibson、Alan R. Kennedy†
DOI:10.1039/b102020j
日期:——
A series of three 5,5-diaryl substituted oxazolidin-2-ones (diphenyl, dinaphthyl and ditolyl) have been synthesised. Studies on the benzylation of the lithium enolates of N-acyl derivatives reveal that the yields obtained were sensitive to the method of quenching the reaction. This was particularly acute for the 5,5-diphenyl system where effective yields (69%) and high diastereoselectivities (dr 98 ∶ 2)