Thermal Reactions of Terpene Hydrocarbons.

An effort to generalize the thermal isomerization of 6,6-dimethylbicyclo[3.1.1]heptanes and 6,6-dimethylbicyclo[3.1.1]heptenes: Comparative pyrolysis of pinane, α-pinene, and β-pinene

“…The activation entropies D z S are negative and the frequency factors log 10 A are smaller than 12.0. Hence, those values indicate a ''tight'' transition state being characteristically for reactions passing through six-membered ring transition states [27,28], the assumption is confirmed that the reactions responsible for the disappearance are ene-cyclization (4, 5 and 8) [1,5]sigmatropic hydrogen shift (6) or other sigmatropic reactions (7).…”

“…Therefore, the aim is to search for stereo-, enantio-, and/or chemoselective routes for the (de)functionalization of terpenes. Besides catalytic routes, the selective ring-opening of rigid bicyclic monoterpenes is an interesting method [6][7][8][9][10].…”

“…Since photochemical reactions are highly selective but afford the use of large amounts of pure solvents, sensitizers, and long reaction times, these methods are from lower industrial importance than thermally induced reactions. Various examples of pyrolyses of pinane-type compounds are reported in literature [6][7][8][9][10], but studies investigating systematically the influence of substituents on those thermal rearrangements are rare [13][14][15][16][17]. The first approach was presented by Coxon et al investigating the pyrolysis of various hydroxypinane derivatives [14][15][16] as well as of pinanones [13], laying the groundwork for identification of various products.…”

Synthesis of Polyisoprene Terpenoid Dendrons and their Applications in Oligo(phenylene ethynylene)s as “Shells”

“…Keywords: dendrimers · hydrocarbons · oligomerization · polymers · terpenoids penes, [21] which are derived from five carbon isoprene units [22] assembled and modified in thousands of ways. [23] They are classified by the number of isoprene units in their skeleton, from one to many.…”

“…Second, it is likely that dendrimers will have structures and properties analogous to those of terpenoid compounds when the isoprene monomers connected head‐to‐tail act as a hydrophobic part. Practically, the terpenoids,20 which are sometimes called isoprenoids, are an enormous and varied class of naturally occurring organic chemicals similar to terpenes,21 which are derived from five carbon isoprene units22 assembled and modified in thousands of ways 23. They are classified by the number of isoprene units in their skeleton, from one to many.…”