Regioselective ring opening in substituted benzocyclopropenes. An alternative or complementary mechanism for electrophilic substitution involving attack at .alpha. bond
Regioselective ring opening in substituted benzocyclopropenes. An alternative or complementary mechanism for electrophilic substitution involving attack at .alpha. bond
Synthesis of cycloproparenes<i>via</i>aromatization of 7-Oxanorbornenes with Low-Valent titanium
作者:Paul Müller、Jean-Pierre Schaller
DOI:10.1002/hlca.19890720721
日期:1989.11.1
1H-Cyclopropa[b]naphthalene 3c and the 2,7-diphenyl-substituted derivative 3a have been synthesized via cycloaddition of the appropriate isobenzofurans 1a and 1b to 1-bromo-2-chlorocyclopropene and aromatization of the adducts with low-valent Ti. The same procedure afforded the 2,7-dimethyl-H-cyelopropa[g]isoquinoline (15), but failed for the parent azacompound. Reaction of adducts of furans to 1-
通过将适当的异苯并呋喃1a和1b环加成至1-溴-2-氯环丙烯并用低价Ti进行加合物的芳构化反应,合成了1 H-环丙烷[ b ]萘3c和2,7-二苯基取代的衍生物3a。。相同的步骤,得到2,7-二甲基- ħ -cyelopropa [克]异喹啉(15),但未能父azacompound。呋喃与1-溴-2-氯环丙烯的加合物与低价Ti生成的环丙烷苯19和1,6-二卤代-1,3,5-环庚烷18的混合物反应。后者可以用BuLi转化为环丙苯。
Regioselectivity and Mechanism of Dihalocarbene Addition to Benzocyclopropene
作者:Marina Khrapunovich、Ekaterina Zelenova、Lillian Seu、Alexis N. Sabo、Aidan Flaherty、Dina C. Merrer
DOI:10.1021/jo071203+
日期:2007.9.1
regioselectively to aryl-substituted benzocyclopropenes to produce dihalobenzocyclobutenes. The regioselectivity of addition is not due to steric effects but depends on the electronic donor or acceptor ability of the substituent. B3LYP/6-31G* calculations show preferential :CCl2 addition to substituted benzocyclopropene through electrophilic attack on the benzocyclopropene π-system (Ea = 1.1−2.4 kcal/mol)
二卤代卡宾向区域选择性地加成芳基取代的苯并环丙烯,以生产二卤代苯并环丁烯。加成的区域选择性不是由于空间效应,而是取决于取代基的电子给体或受体能力。B3LYP / 6-31G *计算表明:通过对苯并环丙烯π系统的亲电攻击(E a = 1.1-2.4 kcal / mol),CCl 2可优先添加到取代的苯并环丙烯中,而不是将C-Cσ键插入环丙烯基部分中(E a = 5-24 kcal / mol)。π-加成通过一个过渡态选择性地向亚二甲苯中间体或直接向苯并环丁烯产物进行。
MULLER P.; SCHALLER J. -P., CHIMIA, 40,(1986) N 12, 430-431