Syntheses of Phencyclone Analogues. Applications for NMR Studies of Hindered Rotations and Magnetic Anisotropy in Crowded Diels–Alder Adducts
Syntheses of Phencyclone Analogues. Applications for NMR Studies of Hindered Rotations and Magnetic Anisotropy in Crowded Diels–Alder Adducts
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苯环酮类似物的合成在拥挤狄尔斯-桤木加合物中受阻旋转和磁各向异性的 NMR 研究中的应用
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发表时间：
2001
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通讯作者：
Kerstin Rosmarion
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作者：
R. Callahan;K. Marshall;R. Rothchild;Kerstin Rosmarion
本科生有机化学特别实验室项目的基础上的phencyclone，1（一个有效的狄尔斯-阿尔德二烯）的合成，并制备了一系列高度受阻的狄尔斯-阿尔德加成物的phencyclone，前面描述。这里介绍的类似物1的合成的细节作为这些项目的扩展。类似物，3，6-dibromophencyclone，2，和各种亲二烯体的加合物，可以由有机化学本科生制备。这些加合物（1或2）非常适合学生通过NMR表征，以检查受阻旋转，磁各向异性和动态NMR光谱学的各个方面，使用现代一维和二维多核方法与中场仪器（7 T），观察1H，13 C和19 F。2的使用有效地使学生的潜在目标化合物的范围加倍。Diels-Alder加合物（及其前体）已通过分子模拟方法进行了研究。本文描述了2与亲双烯体N-（4-二甲氨基-3，5-二硝基苯基）马来酰亚胺（“Tuppy马来酰亚胺”）4的反应，以形成加合物5。化合物5已经通过1D和2D 1H和13 C NMR进行了很好的表征，并且说明了学生可以从2制备的广泛的加合物。5的结构，确定在半经验（AM-1）水平的几何优化，包括在这里。
Undergraduate organic chemistry special laboratory projects based upon the synthesis of phencyclone, 1 (a potent Diels-Alder diene), and the preparation of a series of highly hindered Diels-Alder adducts of the phencyclone, were described earlier. Details of the synthesis of an analogue of 1 are presented here as an extension of these projects. The analogue, 3,6-dibromophencyclone, 2, and adducts from a wide range of dienophiles, can be prepared by undergraduate organic chemistry students. These adducts (from 1 or 2) are eminently suitable for student characterization by NMR to examine aspects of hindered rotation, magnetic anisotropy, and dynamic NMR spectroscopy, using modern one- and two-dimensional multinuclear methods with a medium-field instrument (7 T), to observe 1H, 13C, and 19F. Use of 2 effectively doubles the range of potential target compounds for students. The Diels-Alder adducts (and their precursors) have been studied by molecular modeling methods. This present paper describes the reaction of 2 with 4, the dienophile N-(4-dimethylamino-3,5-dinitrophenyl)maleimide (“Tuppy’s maleimide”), to form the adduct 5. Compound 5 has been well-characterized by 1D and 2D 1H and 13C NMR, and is illustrative of the wide range of adducts that can be made from 2 by students. The structure of 5, as determined by geometry optimization at the semiempirical (AM-1) level, is included here.