structure elucidation of a pyrazolo[3,4]pyran derivative by nmr spectroscopy结构说明pyrazolo[3,4]吡喃衍生物通过核磁共振光谱学.pdf

Molecules 2007, 12, 1117-1124 molecules ISSN 1420-3049 © 2007 by MDPI /molecules Full Paper Structure Elucidation of a Pyrazolo[3,4]pyran Derivative by NMR Spectroscopy Xuehui Liu and Yuxin Cui * State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100083, P. R. China; E-mails: xhliu@ (for X. Liu) * Author to whom correspondence should be addressed; E-mail: yxcui@ Received: 12 April 2007; in revised form: 13 May 2007 / Accepted: 14 May 2007 / Published: 24 May 2007 Abstract: The structure of a representative pyrazolo[3,4]pyran derivative was determined by 1D and 2D NMR techniques. Complete 1H and 13C chemical shifts for this compound are reported. Careful analysis of the HMBC (Heteronuclear Multi-Bond Correlation) spectrum helped to elucidate the configuration of the derivative around C7 and C8. The results showed that the characteristic double-strong and double-weak cross peak pattern in the HMBC spectrum for C7 and C8 might be useful for establishing the structures of other pyrazolo[3,4]pyran derivatives. Keywords: NMR; HMBC; nJCH; pyrazolo[3,4]pyran; proton-deficient compound. Introduction Recent advances in chemical biology have prompted a need for reliable methods and strategies for combinatorial synthesis of abundant small molecule libraries, which can be used to elucidate the function of proteins [1]. One attractive approach is the development of chemistry based on cascade [2,3] or