Nucleophilic attacks on carbon–carbon double bonds. Part XXII. Base catalysis, leaving group effects, and solvent effects in several nucleophilic vinylic substitutions by amines
作者:Zvi Rappoport、Alain Topol
DOI:10.1039/p29750000863
日期:——
anilines with 1-chloro-(and 1-bromo-)2,2-dicyano-1-p-nitrophenylethylenes (7) show very mild catalysis by the amine, while the reactions of 1-chloro-(and 1-bromo-)2-cyano-2-methoxycarbonylethylenes (9) with p-cyanoaniline, and of other electrophilic olefins with piperidine and morpholine show no catalysis. The reactivity ratios of the leaving groups in system (6) are: kOMs/kCl= 10·4–59·7; kOTs/kCl=
从1-X-2,2-双乙氧基羰基-1-对硝基苯基乙烯[6; X = Cl,OSO 2 Me(OMs),OSO 2 C 6 H 4 Me- p(OTs),OSO 2 C 6 H 4 Br- p(OBs)]由哌啶和吗啉在MeCN,四氢呋喃(THF)和EtOH和EtOH中的苯硫醇根离子是二阶的(速率常数k obs)。苯胺与1-氯-(和1-溴-)2,2-二氰基-1- p的反应-硝基苯基乙烯(7)显示出非常温和的胺催化作用,而1-氯-(和1-溴-)2-氰基-2-甲氧基羰基乙烯(9)与对氰基苯胺的反应以及其他亲电烯烃与哌啶的反应和吗啉没有催化作用。系统(6)中离去基团的反应比为:k OMs / k Cl = 10·4–59·7;k OTs / k Cl = 10·6-29·9;k OB / K OTs = 1·56–2·85,对于系统(7)和(9),k Br / k Cl= 0·67-1·32。对于大多数系统,溶剂对反应性的影响是MeCN>