Sesquiterpenes synthesis

New examples of application appear regularly. In the following one [248] phenylsulfenylation of nopinone (4) was followed by oxidation to the sulfoxide. Pummerer rearrangement of the latter led directly to the a-phenylthio substituted a-unsaturated ketone (6) (overall yield 94%), starting material for further elaboration of natural sesquiterpene synthesis via 4,4-disubstituted nopinones (7). 

Properly alkylated bicyclo[4.2.0]-octan-2-ones formed by 2+2 photocycloaddition of alkenes to cyclohexenones cleave to 5, -unsaturated ketones, one example leading to a sesquiterpene synthesis [73]. 

The ability of a methanesulphonate substituent to function as a leaving group (compare equation 124, Section VI.E.2) in an intermediate cyclopropane permits transformation of a bicyclo[4.4,0]decene derivative into a compound with a hexahydroazulene skeleton having potential for sesquiterpene synthesis(equation 76). 

Following these guidelines, the selenoxide elimination procedure has proved particularly useful for the synthesis of terminal double bonds, for example the introduction of vinyl groups during sesquiterpene synthesis as illustrated in equation (47). 

Hollmshead, D.M., Howell, S.C., Ley, S.V., Mahon, M., Ratdiffe, N.M., and Worthington, P.A. (1983) The Diels-Alder route to drimane related sesquiterpenes synthesis of dnnamolide, polygodial, isodrimeninol, drimenin and warburganal. J. Chem. Soc. Perkin Trans. 1,1579-1589. 

Hayashi, Y., M. Nishizawa, and T. Sakan Interconversion of Pterosins, Illudoid Sesquiterpenes Synthesis of Onitin (4-Hydroxypterosin Z) and ( + )-Pterosin D. Chemistry Letters 1974, 945. 

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