文献类型：期刊文献

英文题名：Methyl Group in Isocopalane Derivative Showed an Unusual Negative 1H NMR Chemical Shift

作者：Xiao, Xiong[1];Chen, Tianqi[1];Zhang, Fengfeng[1];Cheng, Jiagao[1];Wu, Peiying[3];Ren, Jiangmeng[1];Zeng, Bubing[1,2]

机构：[1]E China Univ Sci & Technol, Shanghai Key Lab New Drug Design, Sch Pharm, Shanghai 200237, Peoples R China;[2]Chinese Acad Sci, Shanghai Inst Organ Chem, Key Lab Synthet Chem Nat Subst, Shanghai 200032, Peoples R China;[3]Shanghai Univ Tradit Chinese Med, Sch Pharm, Shanghai 201203, Peoples R China

年份：2015

卷号：33

期号：6

起止页码：643

外文期刊名：CHINESE JOURNAL OF CHEMISTRY

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000356425200006)】；

基金：This work was financially supported by National Natural Science Foundation of China (No. 21302053), Science and Technology Commission of Shanghai Municipality (No. 14DZ1900102) and the Fundamental Research Funds for the Central University (No. WY1113007)

语种：英文

外文关键词：shielding effect; diterpenoid; dihydropyrazole; negative chemical shift; computational study

摘要：An unusual negative H-1 NMR chemical shift of methyl group was discovered in condensation product of isocopalane diterpenoid with p-toluenesulfonyl hydrazide. 2D NMR, computational studies and single-crystal X-ray diffraction analysis showed that the C-20 methyl group was shielded.