Acta Phys. -Chim. Sin. ›› 2002, Vol. 18 ›› Issue (05): 420-425.doi: 10.3866/PKU.WHXB20020508

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Ab Inito Study on δ 1HNMR and δ 13CNMR of Taxol and It′s Molecular Geometry

Xu Xuan;Xu Zhi-Guang;Luo Yi-Fan   

  1. Department of Chemistry,South China Normal University,Guangzhou 510631;Department of Natural Drug,Sun Yatsen University of Medical Sciences,Guangzhou 510089
  • Received:2001-10-12 Revised:2001-12-10 Published:2002-05-15
  • Contact: Xu Xuan

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,