WO1997030687A2

WO1997030687A2 - Fragrance precursors

Info

Publication number: WO1997030687A2
Application number: PCT/EP1997/000705
Authority: WO
Inventors: Denise Anderson; Georg Frater; Peter Gygax
Original assignee: Givaudan-Roure (International) S.A.
Priority date: 1996-02-21
Filing date: 1997-02-14
Publication date: 1997-08-28
Also published as: EP1003469A2; WO1997030687A3; JP2000512663A

Abstract

The invention relates to fragrance precursors. In particular, the invention relates to the use of several classes of compounds which can act as fragrance precursors, e.g. in consumer, e.g. cosmetic products, such as deodorants and antiperspirants. These compounds are normally odourless or nearly so, but upon contacting theskin as, for example, in skin care compositions or in personal care compositions, produce fragrances by liberating an odoriferous alcohol.

Description

Fragrance Precursors

The invention relates to fragrance precursors. In particular, the invention relates to the use of several classes of compounds which can act as fragrance precursors, e.g. in consumer, e.g. cosmetic products, such as deodorants and antiperspirants. These compounds are normally odourless or nearly so, but upon contacting the skin as for example, in skin care compositions or in personal care compositions, produce fragrances.

A principal strategy currently employed in imparting odours to consumer products is the admixing of the fragrance directly into the product. There are however, several drawbacks to this strategy. The fragrance material can be too volatile, resulting in fragrance loss during manufacturing, storage, and use. Many fragrance materials are also unstable over time. This again results in loss during storage.

In some cases, fragrances are microencapsulated or treated with cyclodextrins to form inclusion complexes to help decrease volatility and improve stability. However, these methods are for a number of reasons often not successful. In addition, cyclodextrins can be too expensive.

In many consumer products is it desirable for the fragrance to be released slowly over time. Microencapsulation and cyclodextrins have been used to provide slow-release properties, however they are subject to the same limitations as above.

The present invention now provides compounds (and their use), which show a low level of odour, or are even odourless, prior to application to the skin, but which release odorant molecules after application to the skin (that is, they provide a delayed release of the fragrance), in particular to the skin in the axilla. The compounds under consideration are compounds of the formula

A - ORl wherein A represents

O

„ II a) R²— C—

o

. II c) X" 0 s-

II o or o d) R^xO — S

wherein Rl is a radical derived from an odoriferous alcohol of the formula Rl OH, wherein

R² is one or more building blocks selected from an optionally substituted C ι _30-alkyl or C2-30- alkenyl radical, a carbocyclic, aromatic or heterocyclic radical, whereby all these radicals may in addition contain one or more hetero atoms, such as O, N, S, P, and groups such as (OCH2CH2)_n

0 and - C -, -COOR⁴ and/or substituents

0 -OH, - C- , -COOR⁴, -NH- or NH2- ,

R³ is independently H, R¹ , R², X ,

R⁴ is R¹ or R²,

X is H, an alkali metal ion, one equivalent of an earth alkali metal or of the Al, Zn or Fe ion, or an optionally mono-, di- or trisubstituted ammonium ion,

n is 1 -20.

Examples of alcohols R^ OH are primary or secondary alcohols- or phenols - such as:

amyl alcohol hexyl alcohol* 2-hexyI alcohol* heptyl alcohol* octyl alcohol* nonyl alcohol* decyl alcohol* undecyl alcohol* lauryl alcohol* myristic alcohol

3 -methyl-but-2-en- l -ol*

3 -methyl- l -pentanol cis-3-hexenol* cis-4-hexenol*

3,5,5-trimethyl hexanol

3,4,5,6,6-pentamethylheptan-2-ol (Kohinool, International

Flavors & Fragrances)* citronellol* geraniol* oct- l -en-3-ol

2,5,7-trimethyl octan-3-ol (Corps Abricot, Givaudan-Roure)

2-cis-3 ,7-dimethyl-2,6-octadien- l -ol 6-ethyl-3-methyl-5-octen- l-ol (Meo Parf, Givaudan-Roure)*

3,7-dimethyl-oct-3,6-dienol*

3,7-dimethyloctanol (Pelargol, Givaudan-Roure)*

7-methoxy-3,7-dimethyl-octan-2-ol (Osyrol, BBA)* cis-6-nonenol * 5-ethyl-2-nonanol

6,8-dimethyl-2-nonanol (Nonadyl, Givaudan-Roure)* 2,2,8-trimethyl-7(8)-nonene-3-ol (Corps Lavande, Givaudan- Roure) nona-2 , 6-dien- l -ol

4-methyl-3-decen-5-ol (Undecavertol, Givaudan-Roure)* dec-9-en- l -ol benzylalcohol

2-methyI undecanol

10-undecen- l -ol

1 -phenyl ethanol* 2-phenyl ethanol*

2-me thy 1-3 -phenyl- 3 -propenol

2-phenyl propanol*

3-phenyl propanol*

4-pheny 1-2- butanol 2-methyl-5-phenyl pentanol (Rosaphen, H+R)*

2-methyl-4-phenyl-pentanol (Pamplefleur, International

Flavors & Fragrances)*

3-methyl-5-phenyl pentanol (Phenoxanol, International

Flavors & Fragrances)* 2-(2-methylρhenyl)-ethanol *

4-( l -methylethyl) benzene methanol (International Flavors

& Fragrances)

4-(4-hydroxyphenyl)butan-2-one *

2-phenoxy ethanol* 4-( l -methylethyl)-2-hydroxy- l -methyl benzene

2-methoxy-4-methyl phenol

4-methyl phenol anisic alcohol* p-tolyl alcohol* cinnamic alcohol* vanillin* ethyl vanillin* eugenol* isoeugenol* thymo l anethol* decahydro 2-naphthalenol borneol* cedrenol (Givaudan-Roure)* farnesol* fenchyl alcohol* menthol* 3,7,1 l-trimethyl-2,6,10-dodecatrien-l-ol alpha ionol* tetrahydro ionol*

2-( 1,1 -dime thy lethyl)cyclohexanol*

3-(l,l-dimethylethyl)cyclohexanol* 4-( 1,1 -dime thy lethyl)cyclohexanol*

4-isopropyl cyclohexanol (Folrosia® Givaudan-Roure)

6,6-dimethyl-bicyclo[3.3.1]hept-2-ene-2-ethanol (Diheptol,

Dragoco)

6,6-dimethyl-bicyclo[3.1.1]hept-2-ene-methanol (Myrtenol, BBA)* p-menth-8-en-3-ol (Isopulegol, Givaudan-Roure)*

3,3,5-trimethyl cyclohexanol

2,4,6-trimethyl-3-cyclohexenyl-methanol*

4-(l-methylethyl)cyclohexyl-methanol (Mayol, Firmenich)* 4-(l,l-dimethylethyl) cyclohexanol

2-(l,l-dimethylethyl)-cyclohexanol (Verdol, International

Flavors & Fragrances)

2,2,6-trimethyl-alpha-propyl cyclohexane propanol

(Timberol, Dragoco)* 5-(2,2,3-trimethyl-3-cyclopentenyl)-3-methyl pentan-2-ol

(Sandalore® Givaudan-Roure)*

3-methyl-5-(2,2,3-trimethylcyclopent-3-enyl)pent-4-en-2-ol

(Ebanol, Givaudan-Roure)*

2-ethyl-4(2,2,3-trimethyl cyclopentyl-3-enyl)but-2-en-l-ol (Radjanol, Givaudan-Roure)*

4-(5, 5, 6-trimethylbicy cio [2.2. l]hept-2-yl) -cyclohexanol

(Sandela, Givaudan-Roure)

2-(2-methylpropyl)-4-hydroxy-4-methyl-tetrahydropyran*

(Florosa Q, Quest)* 2-cyclohexyl propanol*

2-(l,l-dimethylethyl)-4-methyl cyclohexanol (Rootanol,

BASF)* l-(2-tert-butyl-cyclohexyloxy)-2-butanol (Amber Core, Kao)* l-(4-isopropyl-cyclohexyl)-ethanol (Mugetanol, H&R)* etc.

^♦preferred alcohols

It is a matter of course, that it is not possible to give a complete list of the odoriferous alcohols R^ OH, which alcohols are liberated as a result of the desired cleavage of the esters I by bacteria, in particular axilla bacteria, and which alcohols are then capable of imparting agreeable odours.

The skilled artisan is, however, quite aware of those alcohols, which provide a positive contribution to the fragrance compositions.

Examples of preferred acids which fall under formula I a) are :

acetic acid nonanoic acid decanoic acid undecanoic acid

3-hydroxy butyric acid 3-hydroxy-3-methyl butyric acid

3-hydroxy-3-methyl-undecanoic acid

3-hydroxy-3-ethyl-undecanoic acid

3-hydroxy undecanoic acid lauric acid 3-hydroxy dodecanoic acid

3-hydroxy-3-methyl-dodecanoic acid

3-hydroxy-3-ethyl-dodecanoic acid myristic acid stearic acid hydroxystearic acid isostearic acid palmitic acid arachidic acid behenic acid stearoyi lactylic acid sorbic acid undecylenic acid linoleic acid linolenic acid oleic acid ricinoleic acid arachidonic acid succinic acid adipic acid sebacic acid citric acid

3,6-dioxaheptanoic acid

3,6,9-trioxadecanoic acid 3,5,9-trioxaundecanoic acid polyglycol diacid (Hoechst); and "eth" refers to

(polyoxyethylene) acids such as: deceth-7 carboxylic acid laureth-5 carboxylic acid laureth- 10 carboxylic acid isosteareth-6 carboxylic acid isosteareth- l 1 carboxylic acid trideceth-4 carboxylic acid trideceth-7 carboxylic acid trideceth- 15 carboxylic acid trideceth- 19 carboxylic acid; glycolic acid lactic acid malic acid maleic acid tartaric acid benzoic acid o-cresotic acid diphenolic acid salicyclic acid, acrylinoleic acid abietic acid dihydroabietic acid tetrahydroabietic acid glycyrrhetinic acid deoxycholic acid cyclohexanediamine tetra acetic acid biotin

1 -hexadecyl-4-carboxy 2-pyrrolidone l -tetradecyl-4-carboxy 2-pyrrolidone l -decyl-4-carboxy 2-pyrrolidone l -octadecyl-4-carboxy 2-pyrrolidone l -lauryl-4-carboxy 2-pyrrolidone folic acid niacin orotic acid ethylenediaminetetraacetic acid

N-(2-hydroxyethyl)ethylenediaminetriacetic acid pantothenic acid pentetic acid

4-(acetylamino)-butanoic acids; and α-amino acids such as: glycine alanine arginine asparagine aspartic acid glutamic acid histidine isoleucine leucine lysine proline serine threonine tyrosine phenylalanine tryptophan valine; gluconic acid glycyrrhizic acid, thiodiglycolic acid thiodipropionic acid thiosalicyclic acid phenyl thioglycolic acid dithiodiglycolic acid etc.

Those acids which are known to exhibit antibacterial activity would appear to provide beneficial effects in this respect.

From this compilation it can be gathered, that a wide variety of compounds come into consideration. It can, for example, be seen that R² extends from C l to C30 alkyl and alkenyl, and one or more unsaturations may be present, and the respective chains may be linear or branched.

The carbocycles encompass in particular, optionally substituted

cycloalkanes cycloalkenes polycycloalkanes polycycloalkenes

The aromatic rings encompass in particular, optionally substituted

one or more benzene rings naphthalene

The heterocycles encompass in particular, optionally substituted pyridine pyrrole pyrrolidine pyrimidine furane thiophene tetrah ydrofuran quinoline furanose pyranose.

The preferred substituents are as pointed out above. The building blocks may be connected in any desirable manner - as this is readily apparent from the list of preferred acids.

The radicals R³ may be the same or different.

Interesting subgroups of the formula I compounds are the compounds

o R^-S-OR¹ Id

0 O

CH₃C-NH-(CH₂)ιo-C-OR¹ If

O

CH₃(CH₂)₅-C-CH₂CH₂COOR¹ lg

O CH₃0CH₂CH₂-OCH₂CH₂0CH₂COR¹ Ih

In any molecule I exhibiting more than one group -OR¹ , these radicals -OR ¹ can be the same or can be different. The subgroups If to Ii are encompassed by Formula la.

The compounds I may preferably be used as sustained release odorants but also to mask or attenuate undesirable odours or to provide additional odours not initially present in consumer products, i.e. cosmetic products destined for application to human skin such as underarm deodorants or antiperspirants or other deodorants contacting the body, or in hand lotions, baby powders, baby lotions, ointments, foot products, facial cleansers, body wipes, facial make-up, colognes, after-shave lotions, shaving creams, etc.

The compounds I are virtually odourless under normal temperature and atmospheric conditions, i.e. about 10-50 degrees Celsius and about 20 to 100% relative humidity. However, when applied to the body, they undergo a transformation in which the fragrant alcohol is released.

The compounds I are not limited to any particular stereo- isomers, all possible stereoisomers, geometric isomers as well as well as racemates are thus included within the scope of formula I.

The compounds I, upon cleavage, provide alcohols having organoleptic properties and therefore permit the development of methods useful in enhancing the odour of consumer products. These compounds may be used individually in an amount effective to enhance the characteristic odour of a material. More commonly, however, the compounds are mixed with other fragrance components in an amount sufficient to provide the desired odour characteristics.

The amount required to produce the desired, overall effect varies depending upon the particular compounds I chosen, the product in which it will be used, and the particular effect desired.

For example, depending upon the selection and concentration of the compound chosen, when added I either singly or as a mixture e.g. to a deodorant composition at levels ranging from about 0.1 to about 10% by weight, or most preferred about 0.25 to about 4% by weight, an odorant, i.e. an odoriferous alcohol in an "organoleptically effective amount" is released when the deodorant is used. This newly formed odorant serves to enhance the odour of the fragrance and in this way mask, e.g. the underarm odour, depending upon the selection and use levels of the compounds I.

The compounds I can accordingly be used in the manufacture of odorant compositions used in the preparation of cosmetic products, e.g. deodorants and antiperspirants, and as is evident from the above compilation, a broad range of known odorants or odorant mixtures can be used. In the manufacture of such compositions the known odorants or odorant mixtures set forth above can be used according to methods known to the perfumer, such as e.g. from W.A. Poucher, Perfumes, Cosmetics, Soaps, 2, 7th Edition, Chapman and Hall, London 1974.

To sum up, the present invention relates to:

1. A fragrance precursor composition, preferably a composition for application to human skin, containing an organoleptically effective amount of at least one compound of the formula I in a acceptable, preferably a cosmetically acceptable carrier.

2. A fragrance precursor containing product, e.g. cosmetic product, e.g. a personal body deodorant or antiperspirant article, containing at least one compound I.

3. A process for prolonging the effect of diffusion of the characteristic odour of an odoriferous alcohol R^x OH, e.g. on human skin, comprising applying a compound I or a composition as described above.

4. A method of suppressing human body malodour by means of compounds of the formula I, which comprises the application, e.g. to human skin of a cosmetic product as defined above.

5. The use of a compound I or a composition as defined above, e.g. in a consumer, e.g. in a cosmetic product, e.g. in a personal body deodorant or antiperspirant composition. The compounds I can be prepared by using standard methods known to the skilled chemist. These standard methods can be found in the chemical literature.

Thus, these compounds I may be obtained by reaction of the alcohol part, if necessary derivated, with the acid part, if necessary activated, of the molecule I.

An activated acid part is of particular interest, when dealing with the compounds I b), I c) and I d). The details can be taken from the Examples below.

Convenient methods are outlined in the Examples.

Example 1 :

3-Hydroxy-3-methyl-undecanoic acid 9-decenylester

To a refluxing suspension of 2.28 g zinc powder and 25 ml cyclohexane were added 22g 9-decenyl bromoacetate. When the reaction had started, a mixture of 7.7g 9-decenyl bromoacetate and 6.7 ml 2-undecanone were slowly added. After a further reflux of 2 hours, the mixture was poured onto ice/2N HCl/ether. The organic phase was separated, dried over Na2S θ4 and evaporated to dryness. The remaining oil was purified by column chromatography (Silicagel, hexane/ether): 8.84 g colourless oil.

NMR (CDI3) among others: 5.70-5.92 (m, IH), 4.89-5.06 (m, 2H), 4.09 (t,J=7.5Hz, 2H), 3.52 (s, IH), 2.48-2.56(AB syst., 2H).

Example 2:

3-Hydroxy-3-methyl-dodecanoic acid 10-undecenylester

This compound was prepared as above, but starting from 10- undecenyl bromo acetate.

NMR (CDCI3) among others: 5.71-5.92 (m, IH), 4.89-5.06 (m, 2H), 4.1 1 (t,J=7.5Hz, 2H), 3.53(s, IH), 2.48-2.56 (AB syst., 2H). - 14 - Example 3:

(2-Methoxy-ethoxy)-acetic acid 3.7-dimethyl-oct-6-enyl ester

A mixture of 34.9 g citronellol, 30 g 3,6-dioxaheptanoic acid (Hoechst) and 0.25 g p-toluenesulfonic acid in 150 ml cyclohexane was refluxed in a flask equipped with a Dean-Stark trap for 4.5 hours. The reaction mixture was cooled, ether was added and the solution was washed with NaHC03 and H2O. The organic phase was dried and evaporated to dryness to give the crude product.

Purification by distillation yielded: 39.86 g colourless liquid, bp: 130 - 133°C/0.07 torr. NMR (CDCI3) 5.03-5.17 (m, IH), 4.14- 4.27 (m, 4H), 3.55-3.78 (m, 4H), 3.40 (s, 3H), 1.90-2.10 (m, 2H), 1.68 (s,3H), 1.62 (s,3H), 1.10-1.60 (m, 5H), 0.91 (d, J=6 Hz, 3H).

Example 4:

According to the same procedure, the following two compounds were prepared:

(2-Methoxy-ethoxy)-acetic acid hex-3-enyl ester

Starting from cis-3-hexenol and 3,6-dioxaheptanoic acid; NMR (CDCI3) 5.20-5.61 (m, 2H), 4.14 (t, J= 4 Hz, 4H), 3.57-3.78 (m, 4H), 3.40 (s, 3H), 2.36-2.47 (m, 2H), 1.98-2.16 (m, 2H), 0.98 (t, J=6

Hz, 3H).

Example 5:

(2-Methoxy-ethoxy -acetic acid 1.5.7-trimethyl octyl ester

From 6,8-dimethyl-nonan-2-ol and 3,6-dioxaheptanoic acid; NMR (CDCI3) 4.92-5.10 (m, IH), 4.12 (s, 2H), 3.54-3.79 (m, 4H),

3.39 (s, 3H), 0.92-1.71 (m, 10H), 1.25 (d, J=8 Hz, 3H), 0.78-0.90 (m, 9H). Example 6:

f2-f2-Methoxy-ethoxy)-ethoxyl-acetic acid hex-3-enyl ester ilhl cis-3-Hexenol was reacted with 3,6,9-trioxadecanoic acid (Hoechst) as above;

NMR (CDCI3) 5.22-5.61 (m, 2H), 4.12-4.22 (m, 4H), 3.53-3.80 (m, 6H), 3.40 (s, 3H), 2.33-2.48 (m, 2H), 1.98-2.14 (m, 2H), 0.97 (s, J=4 Hz, 3H).

Example 7: (Ii)

(2 l^"2-(3.7-Dime thy l-oct-6-enyloxycarbony Imethoxy )-ethoxyl- ethoxy) acetic acid 3.7-dimethyl-oct-6-enyl ester

For the preparation of this ester, citronellol was reacted with 3,6,9-trioxaundecanedioic acid (Hoechst) as above. NMR (CDCI3) 5.03-5.13 (m, 2H), 4.12-4.26 (m, 8H), 3.14-3.29 (m, 8H), 1.90-2.09 (m, 4H), 1.68 (s,3H), 1.62 (s,3H), 1.10-1.60 (m,

10H), 0.91 (d, J=6 Hz, 6H).

(2- T2-f 3.7-Dimethyl-octa-2.6-dienyloxycarbony Imethoxy )- ethoxyl-ethoxy)-acetic acid 3.7-dimethyl-octa-2.6-dienyl ester

For the preparation of this ester, geraniol was reacted with 3,6,9-trioxaundecanedioic acid (Hoechst).

f 2- 1^"2-( 3.7 -Dimethyl-octa- 2.6-dienyloxyc arbony Imethoxy )- ethoxyl-ethoxyVacetic acid 3.7-dimethyl-oct-6-enyl ester

For the preparation of this ester, geraniol and citronellol were reacted with 3,6,9-trioxaundecanedioic acid (Hoechst).

Example 8 :

2.3-Dihydroxy-succinic acid dihex-3-enyl ester

Tartaric acid was reacted with cis-3-hexenol as above. NMR (CDCI3) 5.22-5.63 (m, 4H), 4.52 (s, 2H), 4.24 (t, J=6Hz, 4H), 3.26 (bs, 2H), 2.38-2.52 (m, 4H), 1.98-2.17 (m, 4H), 0.98 (s, J=8Hz, 6H). Example 9:

4-⁽3.1 2-Dihvdroxy- 10.1 3-dimethyl-hexadecahydro- cyclopentafalphenanthren- 17-yP-pentanoic acid phenethyl ester

Deoxycholic acid was reacted with 2-phenyl ethanol as above. NMR (CDCI3) 7.18-7.39 (m, 5H), 4.28 (t, J=7.5Hz, 2H), 3.51-3.78

(m, 2H), 2.93 (t, J=7.5Hz, 2H), 0.98-2.41 (m, 32H), 0.67 (s, 3H).

Example 10:

l -Hexadecyl-5-oxo-pyrrolidine-3-carboxylic acid 3.7- dimethyl-oct-6-enyl ester

A mixture of 10.00 g of l -hexadecyl-4-carboxy 2- pyrrolidone (U.S. Patent 2 757 125), 6.42 g N,N-dicyclohexyl- carbodiimide, 0.42 g 4-pyrrolidinopyridine, and 4.42 g citronellol in 120 ml dichloromethane was stirred at room temperature for 23 hours. The reaction was filtered, the solid washed with ether and the combined organic layers washed with H2O, HCI, NaHCθ3, and brine. The organic phase was dried and evaporated to dryness. The residue was purified by silica gel chromatography to yield the product: 9.40 g colourless oil NMR (CDCI3) 5.05-5.15 (m, IH), 4.13-4.25 (m, 2H), 3.50-3.68

(m, 2H), 3.12-3.33 (m, 2H), 2.62-2.75 (m, 2H), 1.90-2.10 (bm, 2H), 1.68 (s,3H), 1.62 (s,3H), 1.42- 1.56 (m, 4H), 1.25 (bs, 30H), 0.87- 0.96 (m, 6H).

According to the same procedure, the following compounds were prepared:

Example 1 1 :

l -Hexadecyl-5-oxo-pyrrolidine-3-carboxylic acid hex-3-enyl e s ter

from cis-3-hexenol and l-hexadecyl-4-carboxy 2- pyrrolidone;

NMR (CDCI3) 5.21-5.61 (m, 2H), 4.13 (t, J=6 Hz, 2H), 3.51-3.68 (m, 2H), 3.12-3.40 (m, 2H), 2.62-2.72 (m, 2H), 2.33-2.48 (m, 2H), 1.98-2.17 (m, 2H), 1.43-1.60 (m, 2H), 1.25 (bs, 30H), 0.82- 1.13 (m, 3H).

Example 12:

4-Acetylamino-butyric acid 2-ethyl-4-(2.2.3-trimethyl- cvclopent-3-enyl)-but-2-enyl ester

4-(Acetylamino)-butanoic acid was reacted with 2-ethyl- 4(2,2,3-trimethyl cyclopentyl-3-en- l -yl)-but-2-en- l -ol as above. NMR (CDCI3) 5.42-5.14 (m, IH), 5.18-5.28 (m, IH), 4.52 (s, 2H), 3.28 (t, J=6Hz, 2H), 2.40 (t, J=8Hz, 2H), 1.72-2.31 (m, 10H), 1.98 (s, 3H), 1.58-1.66 (m, 3H), 0.92-1.07 (m, 6H), 0.80 (s, 3H).

Example 13:

3-Hydroxy-3-d .5.7-trimethyl-octyloxycarbonyl)- pentanedioic acid bis-π ,5.7-trimethyl-octyl) ester

A mixture of 44.70 g triethyl citrate and 86.13 g 6,8- dimethyl-nonan-2-ol was heated to 150° C under a nitrogen atmosphere. Then 5 ml tetraisopropyl orthotitanate was added over approximately 15 minutes. Over the next two hours, ethanol was distilled away from the reaction mixture. A vacuum of 0.1 Torr was applied to aid the ethanol distillation. The reaction was cooled and the residue was directly purified by silica gel chromatography to yield the product, a colourless oil. NMR (CDCI3) 4.82-5.19 (m, 3H), 2.70-2.91 (m, 4H), 0.92- 1.70 (m, 40H), 0.78-0.90 (m, 27H).

Example 14:

Acetic acid 3-methyl-5-(2.2,3-trimethylcyclopent-3- enyl pent-4-enyl

Acetyl chloride ( 15.7 g) was added quickly under nitrogen to a solution of 20.8 g of 3-methyl-5-(2,2,3-trimethylcyclopent-3- enyl)pent-4-en-2-ol in 500 ml of cyclohexane. 20.2 g of triethylamine was added dropwise in -30 minutes with cooling, the temperature being maintained at 20° C. After an additional 2 hours stirring at room temperature, the reaction mixture was filtered and the white solid washed with 200 ml of MTBE. The filtrate was washed with 10% sodium bicarbonate solution, 0.1N hydrochloric acid and brine, dried and evaporated to dryness to give 35 g of yellow oil. Purification by distillation yielded 18 g of colourless liquid; bp: 84° C / 0.06 Torr.

NMR (CDCI3) 5.25-5.6 (m, 2H), 5.23 (s, IH), 4.7-4.93 (m, IH), 2.0- 2.45 (m, 4H), 2.03 (3s, 3H), 1.61 (m, 3H), 1.17 (3d, J=6.4 Hz, 3H), 1.01 (2d, J=6.8 Hz, 3H), 0.95 (s, 3H), 0.75 (2s, 3H).

Example 15:

Phosphoric acid 3.7-dimethyl-oct-6-enyl ester dimethyl ester

A mixture of 1 1.1 g citronellol, 23.36 g carbon tetrabromide, and 50 ml pyridine was cooled to 0° C. Trimethyl phosphite (9.6 ml) was added over 15 minutes, upon completion of the addition of trimethyl phosphite the ice bath was removed and the reaction mixture was stirred for an additional 2.5 hours. After the addition of ether the solution was washed with 2N HCI, NaHCθ3, and H2O . Purification by silica gel column chromatography gave the product, 10.74 g, a colourless oil. NMR (CDCI3) 5.03-5.16 (m, IH), 4.02-4.19 (m, 2H), 3.75 (d, J=12

Hz, 6H), 1.90-2.10 (m, 2H) 1.10- 1.82 (m, 5H), 1.68 (s,3H), 1.62 (s,3H), 0.93 (d, J=6Hz, 3H).

Example 16:

Hexadecanoic acid 2-(dec-9-enyloxy-hydroxy- phosphoryloxy) -eth vies ter

To a 0° solution of 2.52 g 2-chloro-4,5-dimethyl-2-oxo-P(^v)- 1 ,3,2-dioxaphosphole (F. Ramirez, Synthesis 1985. 449) in 8 ml dichloromethane was added a solution jf 2.04 g imidazole in 37 ml dichloromethane. After stirring for 15 minutes, a solution of 4.5 g ethyleneglycol monohexadecanoate in 20 ml dichloromethane was added and the mixture stirred at ambient temperature for 2 hours. Then 2.34 g 9-decen- l-ol in 20 ml dichloromethane were added and the whole was stirred overnight. After the addition of dichloromethane the solution was washed with Na2C03, HCI, H2O. The organic phase was dried and evaporated to dryness. The residue was then stirred at 60° with 18 ml water, 9 ml acetonitrile and 3.72 ml triethylamine for 1 hour. After evaporation of the acetonitrile 7.94 g Na2Cθ3 in 75 ml water were added and the whole stirred for 30 minutes. The aqueous solution was washed with dichloromethane and then acidified. Extraction with dichloromethane and evaporation of the solvent gave the crude product which was purified by recrystallisation from methyl formiate: 4.1 1 g, mp: 44-46°; NMR (CDCI3) 8.6 (bs, IH), 5.7-5.92 (m, IH), 4.86-5.05 (m, 2H),

4.15-4.35 (m, 4H), 4.06 (q, J=6.25 Hz, 2H), 2.34 (t, J=8.5 Hz, 2H) 2.04 (bq, 2H), 1.1- 1.75 (b, 38H), 0.88 (t, J=7 Hz, 3H).

The monosodium salt of this acid was prepared by running a THF-solution of the acid through a column charged with Amberlite IRC 86 in its sodium-form. Evaporation of the solvent gave the salt in quantitative yield. NMR (CDCI3): 5.7-5.92 (bm, IH), 4.9-5.06 (m, 2H), 4.15-4.35 (m, 4H), 4.02 (q, J=6.25 Hz, 4H), 2.33 (t, J=7 Hz, 2H) 2.05 (bq, 2H), 1.1-1.75 (b, 38H), 0.88 (t, J=7.5 Hz, 3H).

Example 17:

According to the same procedure, the following two compounds were prepared:

Hexadecanoic acid 2-(undec-10-enyloxy-hydroxy- phosphoryIoxy)-ethyl ester NMR (CDCI3): 9.2 (b, IH), 5.7-5.92 (m, IH), 4.88-5.05 (m, 2H),

4.15-4.34 (m, 4H), 4.03 (q, J=6.3 Hz, 2H), 2.34 (t, J=7.5 Hz, 2H) 2.04 (bq, J=7Hz, 2H), 1.2-1.78 (b, 40H), 0.88 (t, J=7 Hz, 3H).

Sodium-salt: NMR (CDCI3): 5.7-5.91 (m, IH), 4.9-5.05 (m, 2H), 4.1-4.33 (m, 4H), 4.0 (q, J=6.5 Hz, 2H), 2.33 (t, J=7.5 Hz, 2H) 2.05

(bq, J=7Hz, 2H), 1.2- 1.75 (b, 40H), 0.88 (t, J=7 Hz, 3H). Example 18:

Hexadecanoic acid 2-(cis-3-hexen- l -yloxy-hydroxy- phosphoryP-ethyl ester

The compound was prepared starting from cis-3-hexenol.

NMR (CDC13): among others: 6.55 (vb, IH), 5.45-5.6 (m, IH),

5.25-5.37 (m, IH), 4.14-4.33 (bm, 4H), 4.02 (q, J=7.5 Hz, 2H), 2.45 (q, J=7.5 Hz, 2H) 2.34 (q, J=7.5Hz, 2H), 2.06 (quintett, J=7 Hz, 2H).

Sodium salt: NMR (CDCI3): among others: 5.25-5.44 (m, 2H), 4.12-4.24 (b, 2H), 3.87-4.0 (b, 2H), 3.73 (bq, J=7 Hz, 2H), 2.17- 2.33 (m, 2H) 1.95 (quintett, J=7.5 Hz, 2H).

Example 19:

Hexadecanoic acid 2-(hydroxy-phenethyloxy- phosphoryloxyVethyl ester

To a 0° solution of 1.22 g phenylethanol and 5.79 ml 2-tert. butylimino-2-diethylamino- l , 3-dimethylperhydro- l ,3 ,2 diazaphosphorine in 40 ml acetonitrile was added 1.42 g 2- chloro-2-oxo- l ,3,2-dioxaphospholane in 40 ml acetonitrile over a period of 20 minutes. The mixture was stirred for 1 hour at 0° and then for 1.5 hours at room temperature before adding 2.56 g hexadecanoic acid. After 48 hours at 60° the solvent was partially removed and the remainder dissolved in ether/2N HCI. The organic phase was washed with aqueous HCI and water before being evaporated to dryness. The residue was recrystallised to give 3.41 g of product, mp.: 44-45°. NMR (CDCI3): among others: 7.16.-7.35 (m, 5H), 7.05 (bs, IH),

4.16-4.28 (m, 4H), 4.03-4.14 (m, 2H), 3.0 (t, J=7Hz, 2H), 2.30 (t, J=7.5 Hz, 2H).

Sodium salt: NMR (CDCI3): among others: 7.08-7.24 (m, 5H), 3.70-4.15 (m, 6H), 2.86 (bt, J=7.5Hz, 2H), 2.17 (bt, J=7.5 Hz, 2H). Example 20:

The following compound was prepared according to the same procedure:

Hexadecanoic acid 2-f(4-allyI-2-methoxy-phenoxy)-hydroxy- phosphoryloxyl-ethyl ester from the respective di-substituted phenol.

NMR (CDC13): among others: 7.16 (d,J=7 Hz, IH), 6.65-6.76 (m, 3H), 6.4-6.8 (b, IH), 5.82-6.05 (m, IH) 5.03-5.15 (m, 2H) 4.28 (bs, 3H), 3.82 (s, 3H), 3.35 (d, J=6Hz, 2H), 2.30 (t, J=7.5 Hz, 2H).

Sodium salt: NMR (CDCI3): among others: 7.3 (bd,J=8Hz, IH),

6.45-6.55 (b, 2H), 5.74-5.97 (m, IH), 4.97-5.10 (m, 2H) 3.8-4.1 (b, 4H) 3.65 (bs, 3H), 3.24 (bd, J=6.6Hz, 2H), 2.02 (bt, J=7.5 Hz, 2H).

Examples 15 to 20 illustrate the preparation of compounds lb .

Example 21 : (lc)

Sulfuric acid mono-9-decenyl ester ammonium salt

The mixture of 79 g (0.5 mol) 9-decen-l-ol, 40 g (0.4 mol) amidosulfuric acid and 4 g 4-N,N-dimethylamino-pyridine were heated to 150° C during 20 minutes. The reaction mixture was taken up in THF at - 60° C, evaporated and washed with t-butyl methyl ether. After the solid was dried in vacuo, the yield was 83.2 g (94 %); m.p. with decomposition at 230° C. (see also for this procedure Houben-Weyl, volume E 1 1 , p. 1000)

NMR (d6-DMSO): 5.9-5.7 ppm (m; H-C(9)), 5.1-4.9 (m;

2H-C(10)), 3.7 (t, 2H-C( 1)), 2.1-1.9 (m; 2H-C(7)), 1.6-1.2 (m; 6xCH2).

In analogous manner the following compounds have been prepared, using the appropriate alcohols:

sulfuric acid mono-2-phenyI- l -ethyl ester ammonium salt, sulfuric acid mono-3-phenyl- l-propyl ester ammonium salt,

sulfuric acid mono-3-methyl-5-phenyl- l -pentyl ester ammonium salt.

Example 22:

Sulfurous acid diphenethyl ester (Id)

[According to the procedure for n-butyl-sulfite, CM. Suter et al., Organic Synthesis, Coll. Vol. II, p. 112 ff.] In a three-necked flask, fitted with a KPG stirrer, thermometer, condenser and dropping funnel is placed 122.2 g 2- phenylethanol. The condenser is connected to a trap for absorbing hydrogen chloride, and 60.0 g of freshly distilled thionyl chloride is added with stirring over a period of two hours. The reaction mixture is kept at 35-45°C. After the evolution of hydrogen chloride begins, the mixture is heated to 50°C to maintain this temperature (the addition of the first half of the thionyl chloride is exothermic, the second half endothermic). After all the thionyl chloride has been added, the the temperature is raised gradually to 80°C under reduced pressure (200 mbar) over a period of 2 hours to complete the reaction and remove the remainder of hydrogen chloride. The crude product yielded 151.0 g.

10.0 g of the crude product were purified by bulb to bulb distillation at 150°C/0.04 mbar to give 9.2 g of a colorless oil. NMR (CDCI3): 7.1-7.4 (m, 10H); 3.9-4.2 (m,4H); 2.9 (t,J=7.5Hz,4H).

According to the same procedure, the following compound was prepared:

Sulfurous acid didec-9-enyl ester (Id)

[Starting from 156.3 g dec-9-enole and 60.0 g thionyl chloride.]

The crude product yielded 177.7 g. 15.0 g of the crude product were purified by bulb to bulb distillation at 170°C/0.03 mbar to give 12.0 g of a colorless oil. NMR (CDCI3): 5.68-5.93 (m,2H); 4.88-5.06 (m,4H); 3.83-4.10 (m,4H); 1.93-2.13 (m,4H); 1.53- 1.78 (m,4H); 1.19- 1.50 (m,20H). Example 23

1 1 -Acetylamino-undecanoic acid 3.7-dimethyl-oct-6-enyl ester (If)

A mixture of 20.1 g 1 l-(acetylamino)-undecanoic acid (Tetrahedron 18, [1962], 21), 17.5 g N,N-dicyclohexylcarbodi- imide, 1.12 g 4-pyrrolidinopyridine, and 13.9 g citronellol in 300 ml dichloromethane was stirred at room temperature for 23 hours. The reaction was filtered, the solid washed with ether and the combined organic layers washed with H2O, HCI, NaHCθ₃, and brine. The organic phase was dried and evaporated to dryness. The residue was purified by silica gel chromatography to yield the product: 19.8 g colourless oil. NMR (CDCI3): 5.87-6.0 (br, lH), 5.03-5.18 (m, lH), 4.06-4.19 (m,2H); 3.17-3.30 (m,2H), 2.29-2.34 (m,2H), 1.99 (s,3H), 1.90- 2.07 (m,2H), 1.68 (s,3H), 1.62 (s,3H), 1.42- 1.56 (m,5H), 1.35

(bs, 16H), 0.91 (d,J=6Hz,3H).

Example 24

4-Oxo-decanoic acid 2-phenylethyl ester (lg)

4-Oxo-decanoic acid (Synthesis, [1987], 408) was reacted with 2-phenyl ethanol as in Example 3.

NMR (CDCI3): 7.20-7.39 (m,5H), 4.29 (t,J=5.0Hz,2H), 2.89-3.02 (m,2H), 2.51-2.76 (m,4H), 2.94 (t,J=5.0Hz,2H), 1.50- 1.70 (m,2H), 1.21- 1.40 (m,6H), 0.83-0.99 (m,3H).

Example 25

2-(3.7-DimethyI-oct-6-enyloxycarbonyl)-malonic acid bis-

( 3.7-dimethyl-oct-6-enyl)ester

A mixture of 60.13 g citronellol and 27.6 g triethyl methanetricarboxylate was heated, with removal of ethanol, at 155°C for 8.5 hours. The crude mixture was then distilled by thin film distillation to give 30.1 g of a yellow oil. NMR (CDCI₃) 5.03-5.17 (m,3H), 4.50 (s, lH), 4.30-4.40 (m,6H), 1.90-2.1 1 (m,6H), 1.68 (s,9H), 1.61 (s,9H), 1.09- 1.78 (m, 15H), 0.91 (d,J=6Hz,9H).

2-(3.7-Dimethyl-octa-2.6-dienyloxycarbonyl)-malonic acid bis-(3.7 -dime thyl-octa-2.6-dieny Hester

This compound was prepared as above, but starting from triethyl methanetricarboxylate and geraniol.

These novel compounds are compounds of the subgroup R¹ OOC-CH(COOR¹)-COOR¹ of la. R¹ is as defined above.

Example 26

But-2-enedioic acid bis-(3.7-dimethyl-octa-2.6-dienyl)ester

A mixture of 28.83 g dimethyl fumarate, 61.7 g geraniol, 1.2 g aluminum isopropoxide, and 1.2 g sodium carbonate was heated, with removal of methanol, at 140- 160°C for 6 hours. The reaction was cooled, dissolved in ether, and washed with 5%

H3PO₄, water, aqueous NaHCθ3, and brine. Column chromato¬ graphy of a portion yielded a colorless oil. NMR (CDCI₃) 6.88 (s,2H), 5.32-5.46 (m,2H), 5.02-5.14 (m,2H), 4.72 (d,4H), 1.97-2.18 (m,8H), 1.75 (3,6H), 1.67 (s,6H), 1.60 (s,6H).

Example 27

But-2-enedioic acid bis-(3.7-dimethyl-oct-6-enyl)ester

In a manner similar to example 3, this compound was prepared from citronellol and fumaric acid.

These compounds (examples 26, 27) are compounds of the subgroup R» OOC-CH=CH-COOR ^I of la. R¹ is as defined above. The double bond in this group can be E or Z.

Example 28: Testing

a) A solution of 1 % acetic acid 3-methyl-5-(2,2,3- trimethylcyclopent-3-enyi)pent-4-enyl in ethanol was applied to the underarms and chest area of a T-shirt. The shirt was worn for 8 hours by a test subject who had showered but had not applied any deodorant. After an 8 hour time period, the underarms and the chest of the T-shirt were evaluated. The presence of 3- methyl-5-(2,2,3-trimethylcyclopent-3-enyl)pent-4-en-2-ol was clearly and undoubtedly detected, especially in the underarm area.

b ) Axilla bacteria cultures containing 0.1 % precursor I were incubated for 20 hours at 30°. After filtration from the cells, the presence of the parent alcohol was in each case detected by headspace-GC techniques and/or 6 panelists.

The same tests were carried out with inactivated cultures (85°/20 min). The odour of the parent alcohols could not be detected after incubation, excluding therefore a hydrolysis by the medium or the culture.

Example 29:

The following sets forth examples for the use of the "Delayed Release Fragrances" of the present invention in various products. The methods of forming the following compositions are well known to those skilled in the art. All formulations may contain additional ingredients known to those skilled in the art, e.g. colourants, opacifiers, buffers, antioxidants, vitamins, emulsifiers, UV absorbers, silicones and the like. All products can also be buffered to the desired pH. All values are % w/w.

Deo-colognes (four exemplary compositions):

Delayed Release Fragrances (I) 0.5 1 .5 2.5 6.0

Fragrance 0.5 1 .5 2.5 6.0

Triclosan (Ciba-Geigy) 1 .0 - 0.75 1 .0 Ethanol 1 00 1 00 1 00 1 00

Deo-Sticks:

Antiperspirant stick

Ethylene Glycol Monostearate 7.0 Shea butter 3.0

Neobee 1053 (PVO International) 12.0

Generol 122 (Henkel) 5.0

Kesscowax B (Akzo) 17.0 Dimethicone Dow Corning 345 35.0

Aluminium Sesquichlorhydrate 20.0

Delayed Release Fragrances (I) 0.5

Fragrance 0.5

Antiperspirant stick Steary Alcohol 17.0

Castor Wax 3.0

Talc 5.0

Aluminum Zirconium Tetrachlorhydrate20.0

Delayed Release Fragrances (I) 1 .0 Fragrance 1 .0

Dimethicone Dow 245 to 100.0

Clear Deodorant Stick

Witconol APM 43.0

Propylene Glycol 20.0

Alcohol 39C 20.0

Water 7.0

Monamid 150 ADD 5.0

Millithix 925 2.0

Ottasept Extra 0.5

Delayed Release Fragrances (I) 0.75

Fragrance 0.75

Deodorant Stick

Propylene Glycol 69.0

Water 21 .8

Triclosan 0.2

Sodium Stearate 8.0

Delayed Release Fragrances (I) 0.5

Fragrance 0.5

Alcohol free Deodorant Stick Propylene Glycol-3 Myristyl Ether (Witconol APM) 36.0

Propylene Glycol 36.0

Water 1 9.0

Triclosan 0.25 Sodium Stearate 7.75

Delayed Release Fragrances (I) 0.5

Fragrance 0.5

Antiperspirant Aerosol

Absolute Ethanol 15.0 Zirconium Aluminum tetrachlorhydrate 5.0

Bentone 38 1.5

Delayed Release Fragrances (I) 0.75

Fragrance 0.75

S-31 Hydrocarbon propellant to 100

Antiperspirant Pump

Water 57.5

Aluminum Sesquichlorhydrate 20.0

Triton X-102 (Union Carbide) 2.0

Dimethyl Isosorbide (ICI) 20.0 Delayed Release Fragrances (I) 0.25

Fragrance 0.25

Roll-On

Dimethicone DC 354 (Dow Corning) 69.0

Bentone 38 1 0.0 Rezal 36 GP (Reheis Chem.Co.) 20.0

Delayed Release Fragrances (I) 0.5

Fragrance 0.5

In the above, the following components were used:

Triclosan 5-chloro-2-(2,4-dichlorophenoxy) phenol

Neobee 1053 glycerol tricaprate/caprylate

Generol 122 soya sterol

Kesscowax B cetyl alcohol and glycol polymer Witconol APM polypropylene glycol-3 myristyl ether Monamid 150 ADD cocoamide diethanolamine Millithix 925 dibenzylidene sorbitol Ottasept Extra quaternium 18 hectorite Bentone 38 quaternium 18 hectorite Triton X-102 octoxynol- 13 Dimethicone DC 354 mixture of fully methylated linear siloxane polymers end-blocked with trimethylsiloxy units

Rezal 36 GP aluminium zirconium tetrachlorohydrexglycine

Claims

1. A fragrance precursor composition, preferably a composition for application to human skin, containing an organoleptically effective amount of at least one compound of the formula

A - OR¹ wherein A represents

0

II a) R²- -C —

0

. II c) X^{+ '} 0 s —

II

0 o or

0

II d) R^:0 - -s —

wherein R¹ is a radical derived from an odoriferous alcohol of the formula R^ OH, wherein R² is one or more building blocks selected from an optionally substituted C ι _30-alkyl or C2-30 alkenyl radical, a carbocyclic, aromatic or heterocyclic radical, whereby these radicals may in addition contain one or more hetero atoms, such as O, N, S, P, and groups such as (OCH2CH2)n.

0 and - C-, -COOR⁴ and/or substituents

O -OH, - C- , -COOR⁴, -NH- or NH2- , R³ is independently H, R¹ , R², X ,

R⁴ is Rl or R²,

n is 1 - 20

in a acceptable, e.g. a cosmetically acceptable, carrier.

2. A composition according to Claim 1 , wherein, in formula I, A represents the radical a), b), c) or d) as defined in Claim 1.

3. A composition according to Claim 1 , wherein the active ingredient is represented by the formula

4. A composition according to Claim 1 , wherein the active ingredient is represented by the formula

O CH₃(CH₂)₅-C-CH₂CH₂COOR¹ lg

5. A composition according to Claim 1 , wherein the active ingredient is represented by the formula

6. A composition according to Claim 1 , wherein the active ingredient is represented by the formula

O 0

R¹OCCH₂OCH₂CH₂OCH₂CH₂OCH₂COR¹ ϋ - -

7. A composition according to Claim 1 , wherein the active ingredient is represented by the subgroups of la, R' OO C- , CH COOR^-COOR¹ or R¹OOC-CH=CH-COOR¹.

8. A composition according to Claim 1 , wherein the acid R COOH of formula la) is selected from the group consisting of acetic acid, nonanoic acid, decanoic acid, undecanoic acid, 3- hydroxy butyric acid, 3-hydroxy-3-methyl butyric acid, 3- hydroxy-3-methyl-undecanoic acid ,3-hydroxy-3-ethyl- undecanoic acid, 3-hydroxy undecanoic acid, lauric acid, 3- hydroxy dodecanoic acid, 3-hydroxy-3-methyl-dodecanoic acid, 3- hydroxy-3-ethyl-dodecanoic acid, myristic acid, stearic acid, hydroxystearic acid, isostearic acid, palmitic acid, arachidic acid, behenic acid, stearoyi lactylic acid, sorbic acid, undecylenic acid, linoleic acid, linolenic acid, oleic acid, ricinoleic acid, arachidonic acid, succinic acid, adipic acid, sebacic acid, citric acid,

3,6-dioxaheptanoic acid, 3,6,9-trioxadecanoic acid, 3,5,9-trioxaundecanoic acid, polyglycol diacid (Hoechst); and "eth" refers to (polyoxyethylene) acids such as: deceth-7 carboxylic acid, laureth-5 carboxylic acid, laureth- 10 carboxylic acid, isosteareth-6 carboxylic acid, isosteareth- l 1 carboxylic acid, trideceth-4 carboxylic acid, trideceth-7 carboxylic acid, trideceth- 15 carboxylic acid, trideceth- 19 carboxylic acid; glycolic acid, lactic acid, malic acid, maleic acid, tartaric acid, benzoic acid, o-cresotic acid, diphenolic acid, salicyclic acid, acrylinoleic acid, abietic acid, dihydroabietic acid, tetrahydroabietic acid, glycyrrhetinic acid, deoxycholic acid, cyclohexanediamine tetra acetic acid, biotin, l -hexadecyl-4- carboxy 2-pyrrolidone, l-tetradecyl-4-carboxy 2-pyrrolidone, 1 - decyl-4-carboxy 2-pyrrolidone, l -octadecyl-4-carboxy 2- pyrrolidone, l -lauryl-4-carboxy 2-pyrrolidone, folic acid, niacin, orotic acid, ethylenediaminetetraacetic acid, N-(2-hydroxyethyl) ethylenediaminetriacetic acid, pantothenic acid, pentetic acid, 4- (acetylamino)-butanoic acids; and α-amino acids such as: glycine, alanine, arginine, asparagine, aspartic acid, glutamic acid, histidine, isoleucine, leucine, lysine, proline, serine, threonine, tyrosine, phenylalanine, tryptophan, valine; gluconic acid, glucuronic acid, glycyrrhizic acid, thiodiglycolic acid, thiodipropionic acid, thiosalicyclic acid, phenyl thioglycolic acid, dithiodiglycolic acid.

9. A fragrance precursor containing product, e.g. a cosmetic product e.g. a personal body deodorant or antiperspirant article, containing at least one compound I as defined in Claim 1 or 2.

10. A compound of formula A-OR ¹ as defined in Claim 1 , as encompassed by formula

O O

¹¹ " 1

CH₃C-NH-(CH₂)₁₀-C-OR¹ I

11. A compound of formula A-OR¹ as defined in Claim 1 , as encompassed by formula

O CH₃(CH₂)₅-C-CH₂CH₂COOR¹ lg

12. A compound of formula A-OR¹ as defined in Claim 1 , as encompassed by formula

13. A compound of formula A-OR¹ as defined in Claim 1 , as encompassed by formula

14. A compound of formula A-OR¹ as defined in Claim 1 , as encompassed by the subgroup of la, namely formula R O OC - CH COOR^-COOR¹.

15. A compound of formula A - OR¹ as defined in Claim 1 and as illustrated in Examples 1 to 25.

16. Process for prolonging the effect of diffusion of the caracteristic odour of an odoriferous alcohol R^ OH e.g. on human skin, comprising applying a compound I or a composition as defined in Claim 1 or 2.

17. A method of suppressing human body malodour by means of compounds of the formula I as defined in claim I, which comprises the application, e.g. to human skin of a cosmetic product as defined in Claim .

18. The use of a compound I as defined in Claim 1 as a fragrance precursor, e.g. in a consumer product, e.g. in a composition for application to human skin, e.g. in a personal body deodorant or antiperspirant composition.

***