Absolute Configuration of Verticillane Diterpenoids by Vibrational Circular Dichroism

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• 作者：Carlos M. Cerda-Garc&iacute ; a-Rojas ; Hugo A. Garc&iacute ; a-Gutié ; rrez ; Juan D. Herná ; ndez-Herná ; ndez ; Luisa U. Romá ; n-Mar&iacute ; n ; Pedro Joseph-Nathan
• 刊名：Journal of Natural Products
• 出版年：2007
• 出版时间：July 2007
• 年：2007
• 卷：70
• 期：7
• 页码：1167 - 1172
• 全文大小：249K
• 年卷期：v.70,no.7(July 2007)
• ISSN：1520-6025

文摘

Good agreement between theoretical and experimental vibrational circular dichroism curves of (1S,11S,12S)-(+)-verticilla-3E,7E-dien-12-ol (1) established the absolute configuration of this natural diterpene isolated from Bursera suntui.Molecular modeling of 1 was carried out using the Monte Carlo protocol followed by geometry optimization at theB3LYP 6-31G(d,p) level of theory. The 12-membered ring of 1 was found in a single preferred chair-chair-chair-chair conformation. In the six-membered ring a chair prevails over a distorted boat, and the C-OH bond rotationgenerates three predominant rotamers. Validation of the minimum energy conformation for 1 was achieved by comparisonof theoretical and experimental infrared frequencies, vicinal ¹H NMR coupling constants, and X-ray diffraction data.This study confirms that (+)-verticillol 1 isolated from Bursera species has the 1S,11S,12S absolute configuration thatcorresponds to the same enantiomeric series as verticillanes from Sciadopitys and Taxus, while verticillanes from Jackiellaand Jungermannia have antipodal structures.