Disclosed herein are adrenergic compounds represented by the formula ##STR1## wherein m is 0, 1 or 2; R.sub.1, R.sub.2, R.sub.3 and R.sub.7 are taken from the group consisting of hydrogen, hydroxy, loweralkyl, loweralkoxy, halo, amino, acetamido or NHSO.sub.2 R wherein R is taken from the group consisting of hydrogen or loweralkyl, provided that R.sub.1, R.sub.2, R.sub.3 and R.sub.7 cannot simultaneously be hydrogen or halo, and provided that when one of R.sub.1, R.sub.2, R.sub.3 and R.sub.7 is halo, the others cannot simultaneously be hydrogen and when two of R.sub.1, R.sub.2, R.sub.3 and R.sub.7 are halo, the other two cannot simultaneously be hydrogen and provided that R.sub.1 and R.sub.7 cannot simultaneously be methoxy each when R.sub.2 and R.sub.3 are hydrogen; R.sub.1 and R.sub.2 or R.sub.2 and R.sub.3 or R.sub.3 and R.sub.7 taken together can form a methylenedioxy or ethylenedioxy bridge; or R.sub.1 and R.sub.2 or R.sub.2 and R.sub.3 or R.sub.3 and R.sub.7 taken together with the aromatic ring can form a benzimidazole or indole bridge; and R.sub.4 and R.sub.5 are hydrogen or taken together form a closed ring of the formula ##STR2## wherein n is 1 or 2, and the combined solid and dashed line represents a single or double bond when n is 1, and R.sub.6 is taken from the group consisting of hydrogen or loweralkyl, and the pharmaceutically acceptable salts thereof.
Radicals as Exceptional Electron-Withdrawing Groups: Nucleophilic Aromatic Substitution of Halophenols Via Homolysis-Enabled Electronic Activation
作者:Nick Y. Shin、Elaine Tsui、Adam Reinhold、Gregory D. Scholes、Matthew J. Bird、Robert R. Knowles
DOI:10.1021/jacs.2c10296
日期:2022.11.30
understood to be highly electrophilic, their ability to serve as transient electron-withdrawing groups and facilitate polar reactions at distal sites has not been extensively developed. Here, we report a new strategy for the electronic activation of halophenols, wherein generation of a phenoxyl radical via formal homolysis of the aryl O–H bond enables direct nucleophilic aromatic substitution of the halide
虽然以杂原子为中心的自由基被认为是高度亲电子的,但它们作为瞬时吸电子基团并促进远端位点极性反应的能力尚未得到广泛开发。在这里,我们报告了一种卤代酚电子活化的新策略,其中通过芳基O-H键的形式均裂生成苯氧基自由基,使得能够在温和条件下用羧酸盐亲核试剂直接亲核芳香取代卤化物。脉冲辐射分解和瞬态吸收研究表明,中性氧自由基(O • )确实是一个非常强的吸电子基团[σ p – (O • ) = 2.79 vs σ p – (NO 2 ) = 1.27]。其他机理和计算研究表明,关键的苯氧基中间体在这些反应中充当开壳层吸电子基团,相对于底物的闭壳层苯酚形式,亲核取代的势垒降低了 20 kcal/mol 以上。通过使用自由基作为瞬时激活基团,这种均裂电子激活策略提供了一个强大的平台,可以扩大亲核-亲电子偶联的范围,并实现以前具有挑战性的转化。