Synthesis and fragrance properties of some new monoterpene-based carbamates

Fragrances mostly come from molecules known as terpenes, which are fragrant oil that give all botanicals their unique aromatic signature. Terpenes are the most numerous and structurally diverse and abundant plant natural products and they are simple hydrocarbons containing one or more double bond. Also, they all consist of isoprene units (C5)n and more often in cyclic form. In nature, terpenes exist mainly as in the form of hydrocarbons, alcohols and their glycosides, ethers, aldehydes, ketones, carboxylic acids and esters. Because of this chemical diversity, terpenes have great industrial uses especially in fragrances and flavors. Based on the important and widespread odor properties of terpenes, synthetic preparation of terpene-based novel O-geranyl carbamate derivatives (86a-j) were aimed starting from a well-known terpene alcohol, geraniol. For this purpose, O geranylamine 85 was first prepared over a two-step method including allylic bromination and Gabriel amine synthesis reactions. Subsequently, novel O-geranyl carbamate derivatives (86a-j) were synthesized successfully via a base-catalysed condensation reaction of isolated O-geranylamine 85 with various chloroformates. Structures of all the precursors and carbamate products were identified with IR, 1H NMR and 13C-NMR analyses. Finally, O-geranylamine 85 and O-geranyl carbamates (86) were tested for their odor characteristics by expert perfumers and it was understood that they exhibited a variety of fragrance notes like floral, citrus, fresh, mineral, woody-earthy, animalic.