已经开发出一种通用的方法,可通过类似S N 2的反应,将叠氮离子与各种供体-受体环丙烷开环。这种高度区域选择性和立体选择性的过程是通过亲核攻击环丙烷的更取代的C2原子进行的,该中心的构型完全反转。DFT计算结果支持S N2机理,证明环丙烷的相对实验反应性与计算出的能垒之间具有良好的定性相关性。该反应为多种多官能叠氮化物提供了一种简单的方法,产率高达91%。这些叠氮化物具有很高的合成效用,并参与了面向多样性的合成,这是通过已开发的将其转变为五元,六元和七元N杂环以及复杂的环状化合物的多径策略证明的。包括天然产物和药物,如(-)-尼古丁和阿托伐他汀。
<i>N</i>-Iodosuccinimide-Initiated Spirocyclopropanation of Styrenes with 1,3-Dicarbonyl Compound for the Synthesis of Spirocyclopropanes
作者:Ping Qian、Bingnan Du、Ruichun Song、Xiaodong Wu、Haibo Mei、Jianlin Han、Yi Pan
DOI:10.1021/acs.joc.6b01163
日期:2016.8.5
Herein is reported an N-iodosuccinimide-initiated spirocyclopropanation reaction of styrenes with 1,3-dicarbonylcompounds in the presence of white LED light. The reaction proceeds via two C–H and two C–I bond cleavage event, along with two C–C bond formation event, and formation of quaternary centers. These reactions could be carried out at room temperature and tolerated a wide range of substrates
Asymmetric Ring Opening/Cyclization/Retro-Mannich Reaction of Cyclopropyl Ketones with Aryl 1,2-Diamines for the Synthesis of Benzimidazole Derivatives
reaction of cyclopropyl ketones with aryl 1,2‐diamines has been realized using a chiral N,N′‐dioxide/ScIII catalyst. Benzimidazoles containing chiralsidechains were generated under mild reaction conditions in excellent outcomes (up to 99 % yield and 97 % ee). This method also provides efficient access to chiral benzimidazole‐substituted amide and cycloheptene derivatives.
Inherent Reactivity of Spiro‐Activated Electrophilic Cyclopropanes
作者:Patrick M. Jüstel、Alexandra Stan、Cedric D. Pignot、Armin R. Ofial
DOI:10.1002/chem.202103027
日期:2021.11.17
Ring, ring! The reactivity of spiro-activated electrophilic cyclopropanes was studied by following the kinetics of their SN2-type ring-opening reactions with thiophenolate ions in DMSO at 20 °C. The experimentally determined second-order rate constants (k2) correlated linearly with Mayr nucleophilicities N, basicities (pKaH), and Hammett substituent constants of the thiophenolates, but parabolic Hammett
响铃,响铃!通过跟踪螺环活化的亲电环丙烷在 20 °C 的 DMSO 中与苯硫酚离子的 S N 2 型开环反应的动力学,研究了螺环活化的亲电环丙烷的反应性。实验确定的二阶速率常数 ( k 2 ) 与迈尔亲核性N 、碱度 (p K aH ) 和苯硫酚盐的哈米特取代基常数线性相关,但抛物线哈米特图揭示了对转变稳定性的不同亲电子依赖性影响州。
Lewis acid catalysed asymmetric cascade reaction of cyclopropyl ketones: concise synthesis of pyrrolobenzothiazoles
Utilizing the C4 reactive site of cyclopropyl ketones and a chiral N,N′-dioxide-scandium(III) complex as a catalyst, a concise ring-opening/cyclization/thio-Michael cascade method was developed for the synthesis of chiral benzothiazole derivatives from a simple 2-aminothiophenol material. The kinetic resolution and the origin of stereoselectivity were elucidated via a possible catalytic model.