DFT Study on the Possible Intramolecular Rearrangement of Four Monocyclic Monoterpenes

Abstract

<em>As the basis and preliminary work of future experimental study on PAHs formation under high temperature, theoretical computations on the intramolecular rearrangement reactions of sylvestrene (1-methyl-3-vinylcyclohexene) and 1,4-dimethyl-4-vinylcyclohexene are conducted and reveal that they may be transformed to themselves. The conversion between Dipentene and 2,4-dimethyl-4-vinylcyclohexene is also predicted. All the reactions proceed along concerted paths through a single cis-endo transition state with relatively high energy barrier (~200 kJ/mol) and presumably occur when alkenes burn. These possible Cope rearrangement reactions have some characters of stepwise Diels-Alder cycloadditions during which diene and dienophile are replaced by each other and may suggest the complexity of cyclic hydrocarbons formation.</em>