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核磁共振是天然有机化合物结构解析中最重要的手段之一。近年来,随着超导磁体高磁场核磁共振仪的普及应用,也出现了一些新的测定技术,例如,氘代高场位移法,远程选择氢核去偶法,远程C—HJ分解法及二维INADEQUATE法等。本文现结合具体实例介绍这些新技术在天然化合物结构解析中的应用。1.氚代高场位移(deuterium induced upfield shift)在~(13)CNMR中,若碳原子上的氢被氘取代时,则其信号向高场位移。在酰胺及醇类等具有~(13)C-X-H(X=O,或N)的化合物中,这种现象尤易发生。与XH直接相连的α-碳及相邻的β-碳均可观察列高场位移,并可用于结
Nuclear magnetic resonance is one of the most important means of structural analysis of natural organic compounds. In recent years, with the popularization and application of high magnetic field NMR of superconducting magnet, some new measurement technologies have also appeared, for example, the deuterium displacement field method, the remote selective hydrogen nucleus decoupling method, the remote C-HJ decomposition method and Two-dimensional INADEQUATE law. In this paper, with specific examples of these new technologies introduced in the structure of natural compounds in the application. 1. Deuterium induced upfield shift In ~ (13) CNMR, if hydrogen on a carbon atom is replaced by deuterium, its signal is shifted to higher fields. This phenomenon is particularly likely to occur in compounds having - (13) C-X-H (X = O, or N), such as amides and alcohols. The α-carbon directly connected to the XH and the adjacent β-carbon can all be observed in column high field shifts and can be used for the junction