已经测量了从广泛的路易斯碱硼烷加合物中置换 BH 3的奎宁环动力学。这些速率的参数化使得能够开发出离核量表 (NF B ),以量化和预测一系列其他路易斯碱基的离去基团能力。在多个系列 R' 3– n R n X (X = P, N; R' = 芳基, 烷基) 中观察到的可加性允许制定相关的取代基参数 ( n f PB , n f AB ),提供了一种方法计算N F B一系列路易斯碱基的值远远超出了实验得出的值。通过取代基参数n f PB与一系列烷基和芳基 MIDA 硼酸盐在中性条件下的水解速率的相关性,探索了核离性参数的效用。这允许鉴定具有接近反应中心的杂原子的 MIDA 硼酸盐,显示出不寻常的动力学不稳定性或水解稳定性。
Catalyst-free alcoholysis of phosphane-boranes: a smooth, cheap, and efficient deprotection procedure
摘要:
Catalyst-free alcoholytic deprotection of borane-protected phosphorus compounds offers a smooth, efficient, and clean alternative to existing deprotection methods. In this paper we report our results on the general applicability of deprotecting phosphane- and phosphite-borane adducts by means of simple alcoholysis without the use of molecular sieves as a catalyst. Phosphane-boranes bearing at least one aromatic substituent are readily deprotected in high yields. Borane complexes of trialkylphosphanes or phosphites, however, cannot be deprotected in this way. The main merit of our method is its simplicity: apart from evaporation of the solvent, no further work-up or purification is needed. (C) 2009 Published by Elsevier Ltd.