Homoallyl alcohols useful as fragrances

Branched, highly-substituted C9-C13 homoallyl alcohols of formula I,in which R1 and R2 are selected from H or Me and R3 is selected from H, Me and Et.The compounds are useful in fragrance applications in which a floral note is desired.

This is an application filed under 35 USC 371 of PCT/CH2008/000493.

This invention relates to novel odoriferous homoallyl alcohols, more specifically 2,5,5-trialkyl-3-methylenehexan-1-ols, which possess new green-floral odours, and to the use of these perfumery materials in fragrance applications.

Floral bouquets have always been eagerly sought in the fragrance field, and many examples have been prepared and commercialised. Particularly desirable are rose notes that possess green-herbaceous side notes or dry almost earthy-woody characters, to give odorants with reduced sweetness that appear and smell more natural.

It has now been found that 2,5-dialkyl-5-methyl-3-methylenehexan-1-ols constitute a new, well-defined class of odorants situated between rose, hyacinth and lilac, and that these possess these highly-desirable facets that reduce the stereotypical sweetness of rose odorants and incorporate new natural side notes ranging from green-herbaceous to earthy-woody.

There is therefore provided a compound of the formula I,

in which R1and R2are selected from H or Me and R3is selected from H, Me and Et.

The compounds of formula I may be used singly, or in combinations of two or more such compounds.

Particularly preferred compounds of formula I are 2,5-dimethyl-3-methylenehexan-1-ol, 2,5,5-trimethyl-3-methylenehexan-1-ol, 2-ethyl-5-methyl-3-methylenehexan-1-ol, 2-ethyl-5,5-dimethyl-3-methylenehexan-1-ol, 2-isopropyl-5-methyl-3-methylenehexan-1-ol and 2-isopropyl-5,5-dimethyl-3-methylenehexan-1-ol.

Depending on the natures of the substituents R1and R2, the compounds of the present invention comprise one or two chiral centres, and as such exist as racemic or enantiomerically-enriched mixtures of enantiomers. Resolving stereoisomers or employing chiral starting materials adds to the cost of these odorants, so it is preferred to use the compounds as racemic mixtures simply for economic reasons. However, if it is desired to prepare individual stereoisomers, this may be achieved according to methods well known in the art, e.g. preparative HPLC and GC or by stereoselective syntheses, or starting from available chiral raw materials.

Due to their unique green-floral rosy character, the compounds of formula I are especially well suited for use in floral feminine fine fragrances, or in compositions for laundry- or home-care applications.

In addition to their admixture with other fragrances, the compounds of the present invention may be admixed with one or more ingredients or excipients conventionally used in conjunction with fragrances in perfume compositions, for example carrier materials, and other auxiliary agents commonly used in the art, e.g., solvents such as dipropylene glycol (DPG), isopropyl myristate (IPM), and triethyl citrate (TEC).

The compounds of the present invention may be used in a broad range of fragrance applications, e.g. in any field of fine and functional perfumery, such as perfumes, household products, laundry products, body care products and cosmetics. The compounds may be employed in widely varying amounts, depending upon the specific application and on the nature and quantity of other fragrances. The proportions in which the compounds of the present invention are employed in application may vary within a large range of values and will depend upon the nature of the applications one intends to perfume, for example the nature of co-ingredients, and the particular effect that the perfumer seeks. Generally however, one may employ up to about 10% by weight in fine fragrances, e.g. from about 0.5% by weight to about 5% by weight, and up to about 20% by weight based on the perfume composition in other fragrance applications, e.g. laundry products. However, these values are given only by way of example, since the experienced perfumer may also achieve effects or may create novel accords with lower or higher concentrations.

The compounds of the present invention may be employed into the fragrance application simply by directly mixing the perfume composition with the fragrance application, or they may, in an earlier step, be entrapped with an entrapment material such as polymers, capsules, microcapsules and nanocapsules, liposomes, film formers, absorbents such as carbon or zeolites, cyclic oligosaccharides and mixtures thereof, or they may be chemically bonded to substrates, which are adapted to release the fragrance molecule upon application of an external stimulus such as light, enzymes, or the like, and then mixed with the application.

Thus, there is additionally provided a method of manufacturing a fragrance application and consumer products resulting therefrom, comprising the incorporation therein of a compound of formula I as a fragrance ingredient, either by directly admixing the compound to the application or by admixing a perfume composition comprising a compound of formula I, which may then be mixed to a fragrance application, using conventional techniques and methods. Through the addition of an olfactory acceptable amount of a compound of the present invention, or a mixture thereof, the odour notes of a fragrance application will be improved, enhanced or modified.

There is also provided a method for improving, enhancing or modifying a fragrance application, comprising the addition thereto of an olfactorily-acceptable amount of a compound of formula I, or a mixture thereof.

There is further provided a fragrance application comprising:

a) as odorant a compound of formula I or a mixture thereof; and

b) a consumer product base.

As used herein, ‘fragrance application’ includes any products, such as fine fragrances, e.g. eaux de perfume and eaux de toilette; household products, e.g. detergents for dishwasher, surface cleaner, air freshener; laundry products, e.g. softener, bleach, detergent; body care products, e.g. after-shave lotion, shampoo, shower gel, shower and bath salt, hygiene product; and cosmetics, e.g. deodorants, vanishing creams, comprising an odorant. This list of products is given by way of illustration and is not to be regarded as being in any way limiting.

The compounds of formula I may conveniently be prepared by Wittig-Horner-Emmons reaction of 4-methylpentan-2-one or 4-alkyl-4-methylpentan-2-one with ethyl 2-(diethoxyphosphoryl)acetate, as described in, for example, P. Kraft, W. Eichenberger, Eur. J. Org. Chem. 2004, 334-365, followed by deconjugative alkylation of the formed α,β-unsaturated ethyl ester with lithium diisopropyl amide (LDA) and a suitable halogen alkane, as described in, for example, R. M. Cory, B. M. Ritchie, A. M. Shrier, Tetrahedron Lett. 1990, 31, 6789-6792. Reduction of the resulting β,γ-unsaturated ester, for instance with lithium aluminium hydride (LAH), then provides the homoallyl alcohols of formula I.

The invention is now further described with reference to the following non-limiting examples. These examples are for the purpose of illustration only and it is understood that a person skilled in the art can make variations and modifications. The NMR data are given relative to internal SiMe4standard.

A solution of N,N′-dimethylpropyleneurea (DMPU, 40.4 g, 315 mmol) in THF (300 mL) was added at −70° C. within 30 min to a stirred solution of lithium diisopropylamide (LDA, 2Min THF, 157 mL, 315 mmol). After 10 min of stiffing at −70° C., a solution of (E/Z)-ethyl 3,5-dimethylhex-2-enoate (35.7 g, 210 mmol) in THF (300 mL) was added over a period of 45 min The reaction mixture was allowed to warm to −20° C., treated dropwise with iodomethane (44.7 g, 315 mmol), and stirred overnight at room temp. Then, satd. aq. NH4Cl solution (600 mL) was added dropwise, and the reaction mixture was extracted with Et2O (3×400 mL). The combined organic extracts were dried with Na2SO4, and evaporated on a rotary evaporator. The resulting residue was purified by silica-gel flash chromatography (pentane/Et2O, 98:2, Rf=0.18) to furnish the ethyl 2,5-dimethyl-3-methylenehexanoate (23.2 g, 60%) as a colourless liquid. Odour description: fruity-floral-green note with fruity, green, acidic accents and agrestic undertones.

Floriental Feminine Fine Fragrance

At only 1%, 2,5-dimethyl-3-methylenehexan-1-ol conveys to the top note of this complex and yet well-balanced floriental feminine fine fragrance a very natural and pleasant green, floral-rosy signature that harmonies extremely well with the peachy, hesperidic, flowery-fresh agrestic accord around ethyl linalool, allowing sparkling green-natural lily-of-the-valley facets to glimmer through. Besides, 2,5-dimethyl-3-methylenehexan-1-ol carries the composition from the top to the floral rosy heart with its luscious hyacinth character that plays in the main theme of the perfume with a bouquet of rose oil, jasmine, and lily-of-the-valley while it pushes the strength and the character of this floral composition. The scent then finishes into an oriental woody-balsamic, vanillin-laden fond that with its heavy even somewhat dark character emphasizes the delicacy of the rose that, thanks to the very special character of 2,5-dimethyl-3-methylenehexan-1-ol, remains in every facet new, fresh and unprecedented though it is so exuberantly presented.

‘Green Tea’ Fragrance for Cosmetic Formulations

At less than 2.5%, 2,5-dimethyl-3-methylenehexan-1-ol conveys to this ‘Green Tea’ fragrance for cosmetic formulations a special green-floral signature that enriches the ‘green tea’ theme with “vert de lilas” facets reminiscent of lilac, hyacinth and peony, greatly increases the strength, and with its slightly agrestic-earthy aspects the natural character of the composition. In addition, this new green-floral odorant provides lift and a comforting character, which emphasizes functional skin-caring properties of a given cosmetic formulation.