| abstract |
The present invention provides a synthetic route for preparing various isomers of cyclohexane-based coolants, such as methyl ester and menthane carboxamide derivatives, specifically, for example, where the amide nitrogen is substituted with an aromatic ring or aryl moiety. provide. Such a structure has a high cooling capacity and a lasting sensory effect, thereby making it useful in a wide range of consumer products. One synthetic route involves copper-catalyzed coupling of primary menthane carboxamide with aryl halides, and such reactions work best in the presence of potassium phosphate and water. Using this synthetic route, specific isomers including new isomers such as menthane carboxamide isomers having the same structure as 1-menthol and neo isomers having opposite stereochemistry at the carboxamide (C-1) position Can be prepared. The neo isomer unexpectedly has a strong and lasting cooling effect. Also provided are preparation schemes for the neo isomers of other menthyl derivatives useful as coolants, including esters, ethers, carboxy esters, and other N-substituted menthane carboxamides. |