Department of Chemistry, Annamalai University, Annamalainagar, Chidhambaram, Tamil Nadu, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2011 Mar;78(3):1110-8. doi: 10.1016/j.saa.2010.12.062. Epub 2010 Dec 22.
(1)H and (13)C NMR spectra have been recorded for 3,5-bis[(E)-thienylmethylene]piperidin-4-one (1a), 3',3″-dimethyl-3,5-bis[(E)-thienylmethylene]piperidin-4-one (1b), 5',5″-dibromo-3,5-bis[(E)-thienylmethylene]piperidin-4-one (1c), their 1-methyl derivatives 2a-c and 3,5-bis[(E)-thienylmethylene]-2r,6c-diphenylpiperidin-4-one (3a). For selected compounds 2D spectra have been recorded. The spectral data are used to study the configuration and conformation of these molecules. The chemical shifts are discussed in light of steric, electronic and magnetic anisotropic effects. The magnetic anisotropic effects of thiophene ring and phenyl group are noteworthy. (1)H-(1)H COSY spectrum of 2b suggests that long-range (1)H-(1)H coupling, up to seven bonds, is possible in it. HMBC spectrum of 2b displays the magnetic nonequivalence of C-2 and C-6 and protons at these carbons.
(1)H 和 (13)C NMR 光谱已经记录了 3,5-双[(E)-噻吩亚甲基]哌啶-4-酮 (1a)、3',3″-二甲基-3,5-双[(E)-噻吩亚甲基]哌啶-4-酮 (1b)、5',5″-二溴-3,5-双[(E)-噻吩亚甲基]哌啶-4-酮 (1c)、它们的 1-甲基衍生物 2a-c 和 3,5-双[(E)-噻吩亚甲基]-2r,6c-二苯基哌啶-4-酮 (3a)。为选定的化合物记录了 2D 光谱。光谱数据用于研究这些分子的构象和构象。根据空间位阻、电子和磁各向异性效应讨论了化学位移。噻吩环和苯基的磁各向异性效应值得注意。2b 的 (1)H-(1)H COSY 谱表明，在其中可能存在长达七个键的远程 (1)H-(1)H 偶合。2b 的 HMBC 谱显示了 C-2 和 C-6 以及这些碳原子上的质子的磁不等价性。
