<sup>1</sup>H and <sup>13</sup>C Nuclear Magnetic Resonance Studies of the Hindered Phencyclone Adducts of Some Smaller Branched N-Alkyl Maleimides: Rigorous Aryl Proton Assignments with High-Resolution Two-Dimensional (COSY45) Spectroscopy, and Anisotropic Shielding Effects and <i>Ab Initio</i> Geometry Optimizations
作者:Ronald Callahan、Ron Prip、Navroz Shariff、Olga Sklyut、Robert Rothchild、Kevin Bynum
DOI:10.1366/0003702053585426
日期:2005.3
Phencyclone, 1, a potent Diels-Alder diene, reacts with a series of N-alkylmaleimides, 2, to form hindered adducts, 3. The 300 MHz 1H and 75 MHz 13C NMR studies of these adducts at ambient temperatures have demonstrated slow rotations on the nuclear magnetic resonance (NMR) timescales for the unsubstituted bridgehead phenyl groups, and have revealed substantial magnetic anisotropic shielding effects
Phencyclone, 1,一种有效的 Diels-Alder 二烯,与一系列 N-烷基马来酰亚胺反应,2,形成受阻加合物,3。这些加合物在环境温度下的 300 MHz 1H 和 75 MHz 13C NMR 研究表明,在未取代桥头苯基的核磁共振 (NMR) 时间尺度,并在加合物的 N-烷基的 1H 光谱中揭示了显着的磁各向异性屏蔽效应。目标化合物所选的 N-烷基强调较小的支链烷基,包括 C3(异丙基,a);C4(异丁基,b;和叔丁基,c);C5(正戊基,d;异戊基 [异戊基],e;1-乙基丙基,f;叔戊基,g;)和相关的 C8 异构体(1,1,3,3-四甲基丁基 [“t-辛基”] , H)。包括直链正戊基类似物作为参考。目前关于支链 N-烷基马来酰亚胺加合物的工作大大扩展了我们之前对 Nn-烷基马来酰亚胺加合物的汇编。质子分配的关键方法包括“高分辨率”1H-1H 化学位移相关光谱,COSY45。加合物