Stereoselective Total Synthesis of Copa and Ylango Sesquiterpenoids: (−)-Copacamphene, (−)-Cyclocopacamphene, (+)-Sativene, (+)-Cyclosativene

Abstract

EDWARD PIERS, M. BERT GERAGHTY, R. DEAN SMILLIE, and MARCEL SOUCY. Can. J. Chem. 53,2849 (1975).Stereoselective total syntheses of the tricyclic sesquiterpenoids (-)-copacamphene (1) and (+)-sativene (3) and of the related tetracyclic compounds (-)-cyclocopacamphene (2) and (+)-cyclosativene (4) are described. An efficient four-step synthetic sequence was employed to convert the bicyclic dione 5 into the olefinic ketone 8. The latter compound was converted in four steps into the olefinic alcohol 23. Eliminative cyclization of the corresponding tosylate 25 gave (-)-copacamphene (1) in high yield. In similar fashion, (+)-sativene (3) was obtained by cyclization of the olefinic tosylate 42, which in turn was derived via a four-step synthetic sequence from the olefinic ketone 9. Oxidation of the olefinic alcohol 23 afforded the aldehyde 34. Conversion of the latter compound into the p-tosylhydrazone 35, followed by pyrolysis of the corresponding lithium salt 36, gave the pyrazoline 37. Photolysis of 37 afforded, in high yield, (-)-cyclocopacamphene (2). Similarly, (+)-cyclosativene (4) On decrit des syntheses totales et stCreos6lectives des sesquiterpenoides tricycliques (-) copacamphene (1)et (+) sativene (3)et des composCs t6tracycliques (-) cyclocopacamphene (2) et (+) cyclosativtne (4) qui leur sont relies. On a utilise une sequence de synthtse efficace impliquant 4 Btapes pour transformer la dione 5 en cetone non-saturee 8. On a converti ce dernier compose en alcool olefinique 23 en quatre etapes. L'elimination cyclisante du tosylate correspondant 25 donne le (-) copacamphtne (1) avec un bon rendement. D e la mCme maniere, on obtient le (+) sativene (3) par cyclisation du tosylate non-sature 42, qui derive de la cetone non-saturk 9 par I'intermediaire d'une sequence de synthese en 4 etapes. L'oxydation de I'alcool insature 23 fournit l'aldehyde 34 qui est transforme en p-tosylhydrazone 35. La pyrolyse du sel de lithium de cette derniere (36) donne la pyrazoline 37 qui par photolyse conduit, avec un bon rendement, au (-) cyclocopacamphtne (2). On obtient le (+) cyclosativene (4) de la mCme maniere a partir de I'alcool 41 par I'intermediaire de la pyrazoline 46.

New Alloaromadendrane, Cadinene and Cyclocopacamphane Type Sesquiterpene Derivatives and Bibenzyls from Dendrobium nobile

“…The planar structure of 6 was further established according to ; and H-8 and H-14 were found and its relative configuration was accordingly determined. The structure of 6 was finally identified to be 5b,8b,12-trihydroxycyclopacamphane [20]. It is a new sesquiterpene, and has been assigned the trival name dendrobane A.…”

Integrated Analysis of the Bark Oil from Cinnamosma madagascariensis by GC(RI), GC-MS and NMR. 13C NMR data of Cyclocopacamphene and Cyclosativene

“…Thereby, the percentage of the unknown component was increased until it formed 33.7% in a CC fraction. [13]. Unfortunately, the 13 C NMR data were not reported.…”

“…The order of elution was established by adding a small quantity of commercial cyclosativene to the hydrocarbonfraction of CC: cyclocopacamphene (RI a = 1365) was eluted just before cyclosativene (RI a = 1367). Cyclocopacamphene has been obtained by either decarboxylation of cyclocamphenic acids [15] or by a multi-steps synthesis [13]. It has also been isolated [16] (without any detail) from vetiver EO.…”

“…The composition of the leaf oil has been investigated by a combination of GC (Retention indices, RI), GC-MS and 13 C NMR (Table 1). Forty-two compounds were identified, accounting for 96.9% of the whole composition.…”

“…13 C NMR chemical shifts (, ppm) of cyclocopacamphene (CCC) and cyclocopacamphan-12-ol (CCC-12-ol).…”