The zero-valent nickel complexes, which are generated in situ from nickel(I1) complexes by reduction with zinc, have been found to catalyze the cyclooligomerization of butatrienes, 2,3-dihalo-1,3-butadienes, 1,4-dichloro-2-butyne, and 1,l-dibromoethylene to give the corresponding [4]-and [6]radialenes. The formation of the [4]-and (6lradialenes depends on the reaction conditions, especially on solvent, and each product of the reactions can be prepared selectively. This method provides access to the synthesis of novel derivatives of radialenes of theoretical and synthetic interest. The spectral and chemical data indicate the highly symmetrical structure of radialenes Radialenes (polymethylenecycloalkanes) have received considerable attention from both theorists and experimentalists'-" because of their particular arrangement of r-electrons and because of advances in the understanding of their potentials as electron donor and acceptor for organic metals5 and ferromagnetic organic compounds.6 Of the parent radialenes, [ 3]-2 and [4]radialene3 (1 and 2) were reported two decades ago. However, [5]radialene 0002-7863/88/1510-8494$01.50/0 I , , 0 1988 American Chemical Society Nickel-Catalyzed Radialene ConstructionScheme I11

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A bacterial strain, designated KSM-7358, that can use of-cedrene for growth was isolated. The strain was identified as a member of the genus Rhodococcus and catalyzed the novel allylic oxidation of a-cedrene regiospecifically to produce (R)-10-hydroxycedrene (sec-cedrenol) with a very high yield. ai-Curcumene was also produced as a possible metabolite of sec-cedrenol. A possible pathway for the microbial conversion of a-cedrene to sec-cedrenol and a-curcumene is proposed.