Unexpected Differences in the α-Halogenation and Related Reactivity of Sulfones with Perhaloalkanes in KOH−<i>t</i>-BuOH
作者:Cal Y. Meyers、Roch Chan-Yu-King、Duy H. Hua、Vera M. Kolb、Walter S. Matthews、Thomas E. Parady、Toyokazu Horii、Paul B. Sandrock、Yuqing Hou、Songwen Xie
DOI:10.1021/jo025781w
日期:2003.1.1
variety of other important results. 4-Hydroxyphenyl isopropyl sulfone (6) is unreactive with either CCl4 or CBrCl3 in KOH-t-BuOH, its phenoxide anion strongly reducing the electronegativity of the sulfonyl group, thereby inhibiting alpha-anion formation. This effect is reversed by the electron-withdrawing influence of two alpha-phenyls, so that benzhydryl 4-hydroxyphenyl sulfone (8) is readily alpha-halogenated
大多数KOH-t-BuOH中的烷基苯基砜很容易通过CCl(4)进行α-氯化,并通过C阴离子(RARP)反应在COH-t-BuOH中通过CBrCl3进行α-溴化。虽然异丙基间苯二甲砜(4)容易用CCl(4)进行α-氯化,但用更具反应性的CBrCl3处理后,它可以完全回收。随后的研究表明,后者的结果是由于4的弱酸度以及CBrCl3和KOH彼此之间的反应而迅速耗竭所致,并导致了许多其他重要的结果。4-羟基苯基异丙基砜(6)在KOH-t-BuOH中与CCl4或CBrCl3不反应,其酚盐阴离子强烈降低了磺酰基的电负性,从而抑制了α-阴离子的形成。两个α-苯基的吸电子作用可逆转这种效应,从而使苯甲基4-羟基苯基砜(8)易于在KOH-t-BuOH中与CCl4或CBrCl3进行α-卤代。与KOH-t-BuOH进一步接触后,来自8的α-卤代砜分解为二苯甲酮和苯酚。尽管4-甲氧基苯基苯甲基砜的α-卤代衍生