Thermal isomerization of (+)-cis- and (-)-trans-pinane leading to (-)-beta-citronellene and (+)-isocitronellene.
Catalyzed and uncatalyzed rearrangement reactions of terpenoids play a major role in laboratory and industrial-scale synthesis of fine chemicals. Herein, we present our results on the thermally induced isomerization of pinane (1). Investigation of the thermal behavior of (+)-cis- (1 a) and (-)-trans-pinane (1 b) in a flow-type reactor reveals significant differences in both reactivity and selectivity concerning the formation of (-)-beta-citronellene (2) and (+)-isocitronellene (3) as main products. Possible explanations for these results are discussed on the basis of reaction mechanism and ground-state geometries for 1 a and 1 b. To identify side reactions caused from ene cyclizations of 2 and 3, additional pyrolysis experiments were conducted that enabled the identification of almost all compounds in the network of C(10)H(18)-hydrocarbon products formed from 1.
Institute for Technical Chemistry and Environmental Chemistry, Friedrich-Schiller University Jena, Lessingstrasse 12, Jena, Germany.
Achim
A
Stolle
Bernd
B
Ondruschka
Werner
W
Bonrath
Thomas
T
Netscher
Matthias
M
Findeisen
Markus M
MM
Hoffmann
D000081008:Bicyclic Monoterpenes; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D039821:Monoterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature; D013729:Terpenes / Q000737:chemistry*
D000081008:Bicyclic Monoterpenes; D039821:Monoterpenes; D013729:Terpenes; C532173:beta-citronellene; C532174:isocitronellene; C030216:pinane