Ortho-selectivity in SNAr substitutions of 2,4-dihaloaromatic compounds. Reactions with anionic nucleophiles
作者:Michael D. Wendt、Aaron R. Kunzer
DOI:10.1016/j.tetlet.2010.03.124
日期:2010.6
in a variety of solvents. Substrates showed strong preferences for ortho substitution in most cases. Evidence is presented for activating group-dependent coordination, which contributes to very high ortho-selectivity in nonpolar solvents. This also drives the overall reaction rate in these solvents, and is of close to the same magnitude of rate increase derived from polar solvents. para-Products are
亲核加成的有机阴离子与卤素的芳族化合物既定位邻位和对位,以活化基团在各种溶剂中进行了研究。在大多数情况下,基材显示出对邻位取代的强烈偏好。提出了激活依赖于基团的配位的证据,这有助于在非极性溶剂中非常高的邻位选择性。这也驱动了这些溶剂中的总反应速率,并且与极性溶剂产生的速率增加幅度几乎相同。帕拉-通过在质子传递溶剂中使用冠醚可最大程度地提高产品的性能。总体而言,溶剂作用与与胺类亲核试剂的相应反应有很大不同,这主要是由于过渡态中存在的电荷不同以及亲核试剂的溶剂化所致。