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)
已经合成了一系列三个5,5-二芳基取代的恶唑烷-2-酮(二苯基,二萘基和二甲苯基)。对N-酰基衍生物的烯醇锂的苄基化的研究表明,所获得的收率对淬灭反应的方法很敏感。对于5,5-二苯系统来说尤其如此,仅当将反应淬灭到水性缓冲液中时,才能观察到有效收率(69%)和高非对映选择性(dr 98:2)。对N-酰基衍生物的甲基化研究表明, 只有使用烯醇钠才能观察到最有利的结果(58-69%,博士 91:9)。5,5-ditolyl-4-isopropyloxazolidin-2-one被证明在效率和非对映选择性方面更有效(dr 97:3)。随后,烷基化产物的简单碱性水解允许5,5-二芳基取代的恶唑烷-2--2-酮的高回收率和可回收性,而没有任何有害的环内裂解。另外,从碱性水解中以高收率回收了酰基部分,而没有任何外消旋化的迹象。