Jiquilpane Hydrocarbon Skeleton Generated by Two Successive Wagner−Meerwein Rearrangements of Longipinane Derivatives

• Published in: Journal of natural products (Washington, D.C.) D.C.), 2002-11, Vol.65 (11), p.1540-1546
• Main Authors: Román, Luisa U, Cerda-García-Rojas, Carlos M, Guzmán, Ramón, Armenta, Concepción, Hernández, Juan D, Joseph-Nathan, Pedro
• Format: Article
• Language: English
• Subjects: Alicyclic compounds, terpenoids, prostaglandins, steroids; Aliphatic, non-condensed and condensed benzenic, and alicyclic compounds; Chemistry; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Models, Molecular; Molecular Conformation; Molecular Structure; Organic chemistry; Organic compounds; Physics; Preparations and properties; Sesquiterpenes - chemistry; Stereoisomerism; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Terpenoids; X-Ray Diffraction
• ISSN: 0163-3864; 1520-6025
• DOI: 10.1021/np0201570

The molecular rearrangement of (1R,3S,4S,5S,7S,8R,9S,10R,11R)-7,8,9-triacetyloxylongipinan-1-ol (4) under acidic conditions afforded (1S,4R,5R,7S,8R,9S,10S)-7,8,9-triacetyloxyuruap-3(12)-ene (5), while 6, the C(3)-stereoisomer of 4, after two consecutive Wagner−Meerwein rearrangements followed by two 1,2-hydride migrations, afforded (4R,5R,7S,8S,9S,10S,11S)-7,8,9-triacetyloxyjiquilp-3(12)-ene (7), which possesses a new hydrocarbon skeleton. The structures of the new substances were elucidated by 1D and 2D NMR data in combination with X-ray diffraction analyses of the uruapane, longipinane, and jiquilpane derivatives 5, 6, and 14, respectively. Molecular modeling at the ab initio level was used to study the reaction mechanisms, while deuterium labeling was employed to confirm the C−C bond migrations and the hydride shifts.