The present invention relates to enantiomeric menthoxyalkan-1-ol compounds which function as cooling sensates. These compounds are useful as fragrance and flavor compounds in products such as toothpastes, skin lotions and hard candies and other confections.
Substances giving a physiologically cooling and/or refreshing feeling to the human skin or membranes, in particular to the membranes in the mouth, nose, throat, are well known. A representative example is 1-menthol. L-menthol is widely used as a flavor substance which imparts a desirable cooling and/or refreshing feeling. L-menthol is widely used in oral formulations, such as toothpaste and chewing gums; in food and beverage products, such as sherbet and hard candy; and in toiletry products, such as cosmetics and eye pack materials. However, 1-menthol has a strong minty smell and is also volatile. Although 1-menthol has a strong cooling and/or refreshing effect, the effect is not long-lasting.
Other compounds having an effect similar to that of 1-menthol are known. For example, 3-substituted-p-menthane compounds (Japanese Laid Open Patent Number 47-16,647, Japanese Laid Open Patent Number 47-16,649, British Patent Number 1,315,626), N-substituted-p-menthane-3-carboxamide compounds (Japanese Laid Open Patent Number 47-16,648), paramenthanediol compounds (Japanese Laid Open Patent Number 47-16,650), and 3-1-menthoxypropane-1, 2-diol (Japanese Examined Patent Number 61-48,813, U.S. Pat. No. 4,459,425) are disclosed which have an effect similar to that of 1-menthol. Furthermore Japanese Laid Open Patent Number 7-82,200 discloses (2R)-3-{(1R,2S,5R)-[5-methyl-2-(1-methyethyl)cyclohexyl]oxy}-1,2-propanediol.
Among these compounds, the 3-1-menthoxypropan-1,2-diol compound has a low volatility, is almost odorless, and has an excellent cooling effect. Because 3-1-menthoxypropane-1,2-diol does not have an effect on the aroma or flavor of the product, it is widely used in food and beverage products and in cosmetics.
British Patent Number 1,315,626 discloses that compounds having a p-menthane framework exist in cis form or trans forms. The compounds having an equatorial orientation have a stronger cooling and/or refreshing effect compared to the same compounds having an axial orientation, and thus are preferred. For example, 3-(2-hydroxyethoxy)-p-menthane and 3-(2-hydroxy-n-propyloxy)-p-menthane have been disclosed. However, there is no disclosure regarding the relation between the absolute stereochemistry of these compounds and the cool/refreshing feeling effect. While the British Patent does disclose that the d-form has, in most cases, a greater physiological cooling effect, there is no discussion of any preferred absolute configuration. The reference only notes that four geometric isomers arise from substitution at the 3-position of the basic p-menthane structure, and that for each of these geometric isomers, there are a number of optical isomers.
In recent years, consumer preferences for food and beverage products in as well as cosmetic products have become more varied. There is an increasing desire for development of food and/or beverage products as well as cosmetic products that provide cooling and/or refreshing effects, or similar unique type flavor impressions.