A role for fluorine in flavours, fragrances and pheromones?

Fluorine has been used widely to tune the pharmacokinetic properties of bioactive compounds as they progress through development. Accordingly, selective fluorination has had a major impact in the pharmaceuticals and agrochemicals industries and therefore on human health and well being, though in this context it is notable that fluorine has no presence at all in the flavours and fragrance industries. There does not appear to be an obvious molecular basis for this exclusion. It may be that costs have become prohibitive in this market and it may also be that there are negative perceptions of safety for products that will have intimate contact with healthy individuals, though given the impresssive track record of fluorine to influence the properies of bioactives for health improvement it is a striking omission. It seemed timely therefore to bring to the surface the literature that does exist in this area, if for no other purpose than to begin to explore prospects. We extend the survey to literature in the related area of insect pheromone and semiochemical analogues, as such analogues have the lucrative potential to be used in the field in traps and in small quantities to monitor insect populations. On the face of it, it would appear that there are genuine prospects to develop improved molecules for these purposes using fluorine, however the area remains underdeveloped. In this review we collate those studies which have prepared fluorinated analogues of flavours, fragrance and pheromone molecules and, where known, we discuss their efficacy