The phenomenon of the enantioselectivity in odour perception has been investigated intensively in the last years, and for several chiral odorous molecules the most potent stereoisomer or the one showing the best odour profile has already been established. In most cases the complexity of the synthetic procedure or/and its scarce economic feasibility have prevented the commercialization of the optically active form. Nowadays, several isolated enzymes have been made available to be employed as catalysts for stereoselective organic reactions, such as the reduction of carbonylic groups or activated alkenes. The high chemo- and stereoselectivity of enzyme-mediated reactions can be exploited to develop effective and sustainable manufacturing processes to those chiral compounds for which the influence of absolute configuration on odour properties could justify the commercialization in enantiopure form. Moreover, the development of multi-enzyme systems to be used in multistep procedures in one pot or cascade synthesis has the potential to reduce costs by avoiding work-up and purification of synthetic intermediates. Alpha-substituted-alpha,beta-unsaturated ketones can be converted into chiral secondary alcohols showing two sterogenic centres in 1,2 relative position by an enzymatic two-step procedure involving the ene reductase-mediated reduction of the C=C double bond, and the alcohol dehydrogenase-catalysed reduction of the C=O moiety. The application of this technique to the preparation of the best isomers of chiral odorous molecules will be described.

Multi-enzymatic cascade procedures for the synthesis of chiral odorous molecules

248th National Meeting (2014)

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