Some interesting CH_2CH_3 spin systems in several diethyl malonate indene derivatives studied with NMR and molecular modeling

作     者：ZHANG Long1, HE WeiWei1, LIANG YongMin2 & CUI YuXin1 1 State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China 2 State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China 

作者机构：State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Beijing China State Key Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou China 

出 版 物：《Science China Chemistry》 (中国科学（化学英文版）)

年 卷 期：2009年第52卷第7期

页      面：937-942页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学] 

主　　题：electrophilic cyclization spin-spin coupling signal multiplicity molecular modeling spin system aromatic ring 

摘      要：While studying the electrophilic cyclization of acetylenic malonates in synthesizing malonate indene derivatives with high regio and stereo-selectivity, we found that the CH2 and CH3 protons of two COOCH2CH3 groups in some diethyl malonate indene derivatives showed very interesting spin-spin coupling and signal multiplicity. To explain those phenomena, we synthesized several diethyl malonate indene derivatives, and then used 1H NMR spectra and molecular modeling to investigate the CH2CH3 spin system of these two COOCH2CH3 groups in detail. The results showed that the spin systems of CH3CH2 of the two COOCH2CH3 groups in those compounds may exist in different froms (AMX3, ABX3 and A2X3), and the effect of the aromatic ring induced by the phenyl group at the end of the triple bond is the main reason responsible for those phenomena.