1,8‐Cineole: Chemical and Biological Oxidation Reactions and Products

Abstract

ChemPlusChem 2014, 79, 634 -655 635 CHEMPLUSCHEM REVIEWS www.chempluschem.org son. Cineolic acids were generally identified as their methyl esters and sometimes (hydroxycineolic acids) doubly derivatized to form trimethylsilyl ether derivatives of hydroxyl groups before GC-MS analysis.When a sufficient amount of pure product is obtained, 1 H and 13 C NMR spectroscopy are essential for the full identification of isomers, making use of the downfield shift of the proton(s) gem to the OH group(s) and the 3 J coupling constants observed between the vicinal hydrogen atoms. However, the information obtained is frequently obscured in the d = 1-Robert Azerad was born in Oran (Algeria) in 1938. Educated first in Algiers then in Paris (France), he was trained in biochemistry and chemistry and obtained his PhD in Physical Sciences at Paris-Sud University in 1967 with Prof. E. Lederer. He has held positions at the

Retention of Eucalyptol, a Natural Volatile Insecticide, in Delivery Systems Based on Hydroxypropyl‐β‐Cyclodextrin and Liposomes

“…[ 8 ] The chemical oxidation of Euc has been carried out by strong oxidizing reagents to give oxo compounds (3‐oxo‐1,8‐cineole, 5‐oxo‐1,8‐cineole, and 3,5‐dioxo‐1,8‐cineole). [ 9 ] The sites of oxidation are the carbon 3 and/or 5. The encapsulation of Euc can be considered as a potential solution to overcome the drawbacks related to its physico‐chemical properties.…”

Selective hydroxylation of 1,8- and 1,4-cineole using bacterial P450 variants

“…The monoterpene 1,8-cineole 1 (1,3,3-trimethyl-2-oxabicyclo[2,2,2]octane) is the major component of eucalyptus oil, while 1,4-cineole 2 (4-methyl-1-propan-2-yl-7oxabicyclo[2.2.1]heptane) is found in some plant oils and is also present in lime juice ( Fig. 1) [8][9][10]. Both cineoles are achiral but a single hydroxylation usually leads to the generation of at least two stereogenic centres.…”

“…The oxygenated derivatives of both are important chiral synthons, intermediates in the synthesis of herbicides (e.g. cinmethylin), antimicrobials and fragrances [7,9,[11][12][13][14][15][16][17][18][19][20]. The chemical synthesis of hydroxylated cineole analogues is difficult and requires the use of highly reactive, non-environmentally friendly reagents that usually generate a mixture of racemic products.…”

X‐ray crystal structure of cytochrome P450 monooxygenase CYP101J2 fromSphingobium yanoikuyaestrain B2

“…Oxidation by these enzymes results in a range of oxidation products. CYP101A1 produces predominantly (1 S )‐3α‐hydroxy‐1,8‐cineole and/or its enantiomer (1 S )‐5α‐hydroxy‐1,8‐cineole, whilst the main product of CYP101B1‐catalyzed oxidation is (1 S )‐3α‐hydroxy‐1,8‐cineole (nomenclature of hydroxy‐1,8‐cineoles is assigned as recently proposed by Azerad) . CYP176A1 from Citrobacter braakii has been shown to regiospecifically hydroxylate 1,8‐cineole at position 6 to afford (1 R )‐6β‐hydroxy‐1,8‐cineole .…”