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A general preparation method of the all-(E)-polyprenols 12 has been developed from readily available geranyl sulfone by the chain-extension process utilizing the C5 unit 5 and the chain-termination process utilizing the C5 unit 10 together with the chemoselective reductive desulfonylation. The polyprenols 12 were converted to compounds 3 containing two consecutive prenyl sulfone moieties at the tail end, which underwent the controlled electrophilic cyclization only at the carbon-carbon double bonds that were remote from the flat and rigid benzenesulfonyl groups. [ABSTRACT FROM AUTHOR]

Abstract: Turpentine, an important source of terpenes, is composed mainly of α- and β-pinene. It is possible to pyrolyze β-pinene to form myrcene, which is used as an intermediate for the production of various terpenic alcohols and chemical aromas, as well as vitamins A and E. In the current work we develop a theoretical equilibrium model of the main synthesis reactions that have been described in the literature plus postulated decomposition reactions. The model predicts that 93.5% yields of myrcene from β-pinene would be possible whereas the highest reported yield is 85%. In order to investigate the less than theoretical yields, we investigated the decomposition of myrcene experimentally. The various degradation products that appeared were consistent with a degradation mechanism involving breakage next to conjugated double bonds, producing an alkyl radical. Decomposition of myrcene by this route would form 1,3-butadiene (C4H6) and 4-methyl-1,3-pentadiene (C6H10), which then further decompose into various other products. These results contribute to a better understanding of the production of myrcene by pyrolysis of β-pinene and could form the basis for optimization of product yields. [Copyright &y& Elsevier]