New method of oxidising terpenes holds exciting possibilities for perfumery, flavouring and pharmaceuticals

Researchers in Oxford University¡¦s Department of Chemistry have devised a new method of selectively oxidising terpenes to produce compounds of particular interest to the perfumery, flavour and pharmaceutical industries.

Terpenes and their derivatives are commonly used in industry to modify flavours and fragrances, and new compounds for trial are continuously needed. The terpenes themselves are not of commercial interest, but rather the derivatives that commonly require stereoselective functionalisation at allylic as well as non-activated C-H bonds of the parent terpene. This is one of the most difficult reactions to carry out by conventional reactions since the highly reactive chemical oxidising agents are typically non-selective.

In the Oxford laboratory, considerable excitement is centred on the capability of introducing hydroxyl groups into specific sites in the molecule with a high degree of stereoselectivity. The researchers have developed a method of oxidising terpenes, or other hydrocarbons of interest, by enzymatic techniques. Indeed, non-activated C-H groups can be targeted. Typically, the oxidation produces high yields of relatively pure compounds.

The enzymes of particular interest are specific mutants of haem-containing enzymes, especially mutants of P450. Currently the mutant enzymes are expressed in E. coli as a host to produce an in vivo oxidation system which can be scaled up to large volumes. Initial work has demonstrated the oxidation of R-limonene to (+)-isopiperitenol or (+)-carveol depending on the enzyme and mutant, camphor to 5-exo-hydroxycamphor, (+)-Ą-pinene to (+)-verbenol and valencene to nootkatone.

Isis Innovation, Oxford University¡¦s technology transfer company, is actively seeking partners for the licensing and commercial development of this promising technology.