Chemoselective mono halogenation of β-keto-sulfones using potassium halide and hydrogen peroxide; synthesis of halomethyl sulfones and dihalomethyl sulfones
摘要:
The synthesis of alpha-halo beta-keto-sulfones using potassium halide and hydrogen peroxide as a chemoselective mono halogenation reagent and the synthesis of alpha, alpha-symmetrical and asymmetrical dihalo beta-keto-sulfones and alpha-halo, alpha-alkyl and beta-keto-sulfones is described. Base induced cleavage of alpha-halo beta-keto-sulfones, alpha,alpha-dihalo beta-keto-sulfones, and alpha-halo, alpha-alkyl beta-keto-sulfones afforded the corresponding halomethyl sulfones, dihalomethyl sulfones and haloalkyl sulfones. (c) 2006 Elsevier Ltd. All rights reserved.
Vicarious nucleophilic substitution of hydrogen in nitroderivatives of five-membered heteroaromatic compounds
作者:Mieczyslaw Makosza、Ewa Kwast
DOI:10.1016/0040-4020(95)00445-e
日期:1995.7
Nitro derivatives of thiophene, furan and pyrrole react with carbanions containing leaving groups giving products of replacement of hydrogen with functionalized alkyl substituents. Many specific features of this reaction are discussed.
Vicarious Nucleophilic Substitutions of Hydrogen in 1,1,1-Trifluoro-<i>N</i>-[oxido(phenyl)(trifluoromethyl)-λ<sup>4</sup>-sulfanylidene]methanesulfonamide
作者:Tadeusz Lemek、Grażyna Groszek、Piotr Cmoch
DOI:10.1002/ejoc.200800390
日期:2008.8
1,1,1-Trifluoro-N-[oxido(phenyl)(trifluoromethyl)-λ4-sulfanylidene]methanesulfonamide reacts with carbanions bearing a leaving group to give vicariousnucleophilicsubstitution (VNS) of hydrogen products with moderate yields. This is the first example of the VNS process at a benzene ring activated by an electron-withdrawing group other than a nitro group. The orientation of the substitution is exclusively
electrophilic nature of quinoxaline has been explored in the vicarious nucleophilic substitution (VNS) of hydrogen with various carbanions as nucleophiles in an attempt to develop a general method for functionalizing the heterocyclic ring. Only poorly stabilized nitrile carbanions were found to give the VNS products. 2-Chloroquinoxaline gave products of SNAr of chlorine preferentially. A variety of quinoxaline
喹喔啉的亲电性质已在氢与各种碳负离子作为亲核试剂的替代亲核取代 (VNS) 中进行了探索,以试图开发一种使杂环功能化的通用方法。只有不稳定的腈碳负离子被发现能提供 VNS 产品。2-氯喹喔啉优先生成氯的S N Ar产物。在与喹喔啉N-氧化物的 VNS 反应中,已经制备了多种含有氰基烷基、磺酰烷基、苄基或酯取代基(包括氟化的)的喹喔啉衍生物。
Makosza, Mieczyslaw; Kinowski, Andrzej; Danikiewicz, Witold, Liebigs Annalen der Chemie, 1986, # 1, p. 69 - 77