Borneol

Borneol is a bicyclic organic compound and a terpene derivative. The hydroxyl group in this compound is placed in an endo position. The exo diastereomer is called isoborneol. Being chiral, borneol exists as enantiomers, both of which are found in nature: d-borneol (also written (+)-borneol, dextroborneol, dexborneol) and l-borneol (or (−)-borneol, levoborneol). Both borneol and isoborneol belong to the category of 2-bornanol, a derivative of bornane. Some sources such as PubChem and CHEBI use the term borneol to refer to the entire category of 2-bornanols while others such as KEGG use the term borneol to refer to the compounds with endo hydroxyl only.

Borneol is a bicyclic organic compound and a terpene derivative. The hydroxyl group in this compound is placed in an endo position. The exo diastereomer is called isoborneol. Being chiral, borneol exists as enantiomers, both of which are found in nature: d-borneol (also written (+)-borneol, dextroborneol, dexborneol) and l-borneol (or (−)-borneol, levoborneol). Both borneol and isoborneol belong to the category of 2-bornanol, a derivative of bornane. Some sources such as PubChem and CHEBI use the term borneol to refer to the entire category of 2-bornanols while others such as KEGG use the term borneol to refer to the compounds with endo hydroxyl only.

Synthesis

Borneol can be synthesized by reduction of camphor by the Meerwein–Ponndorf–Verley reduction (a reversible process). For flavoring purposes, a racemic mixture of camphor is used as starting material, leading to a racemic mixture of borneol and isoborneol. The chirality can be controlled by changing the chirality of camphor: (+)-camphor gives (−)-isoborneol and (+)-borneol. Reduction of camphor with sodium borohydride (fast and irreversible) gives instead the diastereomer isoborneol.

Natural sources

Borneol is a component of many essential oils. Industrially, natural (+)-borneol is produced from Cinnamomum burmanni (one specific chemotype) and Cinnamomum camphora. Natural (-)-borneol occurs in Blumea balsamifera.

Biosynthesis

Borneol is synthesized using DMAPP as the starting material. DMAPP is then converted to GPP, which is acted upon by a bornyl diphosphate synthase to yield a bornyl diphosphate. A phosphatase then removes the phosphate groups, yielding borneol. The chirality of borneol in a plant depends on the preferred chirality of the bornyl diphosphate synthase. Synthases for either chirality have been sequenced. A downstream product is camphor of either chirality, a reaction catalyzed by (+)-borneol dehydrogenase or (−)-borneol dehydrogenase.

Derivatives

The bornyl group is a univalent radical C 10 H 17 derived from borneol by removal of hydroxyl and is also known as 2-bornyl. Isobornyl is the univalent radical C 10 H 17 that is derived from isoborneol. Bornyl acetate is the acetate ester of borneol. The norborneols are derived from borneol and isoborneol by the removal of methyl groups, analogous to the change from bornane to norbornane. The epiborneols and isoepiborneols are analogously derived from epicamphor. The structural isomer fenchol is a widely used compound derived from certain essential oils. NIST datasheet including full spectroscopic data Borneol in Chinese medicine

Text derived from https://en.wikipedia.org/w/index.php?oldid=1347404937 under CC BY-SA 4.0; modifications have been made.