A new synthesis of 2-aryloxypropionic acids derivatives via selective mono-c-methylation of methyl aryloxyacetates and aryloxyacetonitriles with dimethyl carbonate
作者:Andrea Bomben、Carlos A. Marques、Maurizio Selva、Pietro Tundo
DOI:10.1016/0040-4020(95)00718-n
日期:1995.10
A one-pot procedure for the mono-C-methylation of methyl aryloxyacetates and aryloxyaceto nitnles by dimethyl carbonate (DMC) is reported The reaction is earned out in an autoclave at high temperatures (180–200 ° C) and in the presence of a base (K2CO3 or bart-BuOK). Although DMC is used either as the alkylating agent or as the solvent (30 molar excess with respect to the substrates). The selectivity
据报道,用碳酸二甲酯(DMC)进行一锅法制得的芳基乙酸甲酯和芳氧基乙酰基甲腈的单C甲基化反应。该反应是在高压釜中于高温(180–200°C)且在有高压釜的情况下完成的。碱(K 2 CO 3或bart -BuOK)。尽管DMC既可以用作烷基化剂也可以用作溶剂(相对于底物30摩尔过量)。在完全转化时,对单甲基化产物(分别为2-芳氧基丙酸甲酯和2-芳氧基丙腈)的选择性通常高达99%。没有二烷基化的副产物形式。这种异常行为的原因可以通过涉及初始羧甲基化然后进行甲基化反应的机理来解释。
Synthesis of quinoxaline derivatives <i>via</i> aromatic nucleophilic substitution of hydrogen
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。
Bomben, Andrea; Selva, Maurizio; Tundo, Pietro, Recueil des Travaux Chimiques des Pays-Bas, 1996, vol. 115, # 4, p. 256 - 260