关键词: 紫杉醇, 核磁共振谱, 规范不变原子轨道法, 从头算, 几何构型优化

Abstract: The geometrical conformation of taxol has been optimized by MM3,PM3 and HF/STO3G method,respectively.An ab initio GIAO method at HF/631G level has been used to predict theoretically 1HNMR and 13CNMR chemical shifts for the conformations by three geometry optimization methods.The results show that the calculated δ 1HNMR and δ 13CNMR for the geometrical conformation optimized by HF/STO3G are the most accurate in comparison with experimentally observed data.It is inferred that,therefore,the geometrical conformation optimized by HF/STO3G must probably be approximate to the real one of taxol in d6DMSOD2O70％. From the geometrical conformation of taxol optimized by HF/STO3G,the distances between 4OAc and 3′H,4OAc and 3′Ph,4OAc and 2OCOPh are found to be 0.266 3 nm,0.310 4 nm and 0.370 7 nm,respectively.These distances are within the effective acting distances producing nuclear overhauser effect (NOE),which theoretically supports Williams′ view that there is a NOE effect in taxol molecule,and Velde′s view that there is a hydrophobic cluster formed by 4OAc,3′Ph and 2OCOPh in taxol molecule.

Key words: Taxol, NMR, GIAO(Gaugeindependant atomic orbital), Ab initio,