US3439042A

US3439042A - Synthesis of pseudoionones

Info

Publication number: US3439042A
Application number: US377503A
Authority: US
Inventors: Emile H Eschinasi; Mary Lou Cotter
Original assignee: Givaudan Corp
Current assignee: Givaudan Roure Corp
Priority date: 1964-06-24
Filing date: 1964-06-24
Publication date: 1969-04-15
Anticipated expiration: 1986-04-15

Description

United States Patent 3.439.042 SYNTHESIS OF PSEUDOION ONES Emile H. Eschinasi, Montclair, and Mary Lou Cotter,

East Orange, NJ., assignors to The Givaudan Corporation, New York, N.Y., a corporation of New Jersey No Drawing. Filed June 24, 1964, Ser. No. 377,503 Int. Cl. C07c 33/02 US. Cl. 260594 9 Claims ABSTRACT OF THE DISCLOSURE R may be lower alkyl or lower alkylene having up to 6, C atoms, phenyl, benzyl or cycloaliphatic.

The present invention relates to a novel process for making 6-substituted ionones and to certain novel substances made thereby.

An object of this invention is to provide a novel process for making irones in a technically simple and commercial feasible manner.

Another object is to afford a synthesis for valuable perfume materials from relatively inexpensive raw materials by a process which results in excellent yield and which does not require a large number of steps.

Other objects will become apparent from the following detailed description.

Alpha-irone is a valuable perfume material, as are also the beta and gamma irones. They are found as the principal components in violet flowers.

Irones may be represented by the following structural formula, in which the encircled 3-carbon atom denotes the fact that double bonds are distributed along the neighboring carbon atoms from the 3-position:

Thus, alpha-irone has the double bond in the 3-4 position, beta-irone has the double bond in the 23 position; and gamma-irone has the double bond in the 37 position. It is also known that the alphaand gamma-irones can exist in cis-transforms.

Accordingly, it will be understood that wherever the context so permits or requires the structural or other representation is intended to include all the forms of the 6- substituted ionones, as well as any and all stereoisomers thereof.

Numerous proposals have been made in the patent and scientific literature regarding methods of producing irones. However, the low yields and the large number of steps of prior processes leave much to be desired.

We now have found a new approach to making irones from simple raw materials, in a few steps and in excellent yields. Our process also enables us to prepare other 6-substituted ionones. Indeed, it has been found that the 6-lower alkyl-substituted ionones having from 2 to 6 carbon atoms possess unexpectedly desirable olfactory properties, including, for example, an odor persistency over 7 times that of alpha-irone.

In a broad aspect, our invention comprises the discovery that Grignard reaction products containing alpha-hydrogens next to an alkoxy group could be subject to oxidation to carbonyl derivatives by treatment with an excess of carbonyl derivatives such as acetone, or other ketones, or aldehydes and subsequently reacted with the excess carbonyl reagent to give aldol condensation products. It will, therefore, be appreciated that our invention is not, in this broad aspect, merely limited to a process for making 6- substituted ionones.

Nevertheless, for purposes of illustration and in order to exemplify the preferred way we now envisage for the carrying out of our invention, we shall describe its application in the process for making 6-substituted ionones, more especially, irones, and still more especially, alpharrone.

In the aforementioned broad aspect, and as applied to making alpha-irone, our process, in essence, may be represented in the following accepted abbreviated form:

This reaction sequence represents the fact, for example, that when 6-ketodihydrogeraniol, which we obtained in good yield by the saponification of the perchloric acid-treated epoxydihydrogeranyl acetate, was treated with two moles of methyl magnesium halide and then treated with acetone we obtained a hydrated pseudoirone (III) (R=CH which, upon treatment with mineral acid such as phosphoric acid, was converted to alpha-irone in good yields.

In addition to the 6, 9-dimethyl-9-R-9 hydroxy-undeca- 3-5-dien-2-one (III), a small amount of 3-7 dimethyl-6- R-2-octene-1-6-diol (IIIa) is also obtained in accordance with the present process.

We now believe that the mechanism of the conversion of II to III as depicted in the following reaction sequence involves hydrogen transfer from the primary alkoxide H H COMgX I CH0 H ornoooH: S curls-43H,

R OMgX \OMEX /OMgX IIIb IIIc isopropanol alkoxide IIIb to acetone to form the intermediate aldehyde IIIc and isopropanol alkoxide. The reactive intermediate aldehyde IIIc condenses with excess acetone to form 111 in a typical aldol condensation:

Ill:

III

As already indicated, our process is not limited to the preparation of irones, nor, indeed, merely to the preparation of 6-alkyl ionones, but, instead, it can be applied to form other 6-substituted ionones, including those which are substituted in the keto-containing side chain, as well as reaction products formed by the aldol condensation of IIIc and ketones other than acetone, or aldehydes.

We shall now indicate some of the modifications of our process we presently contemplate, as well as the reaction conditions which we have found to yield satisfactory results.

In place of the epoxydihydrogeranyl acetate (I) we can employ the corresponding acetate formed from neryl acetate or a mixture of neryl and geranyl acetates.

Also, in place of the acetate (I), other esters, such as the formate, the propionate, the butyrate, the benzoate, etc., may be employed. In general, any carboxylic acid ester may be used. For economic reasons it is preferred to use the acetate.

In place of II we may use esters having the formula:

CHORr where R, is an acyl radical, preferably a lower acyl radical having from one up to carbon atoms.

As suitable Grignard reagents, RMgX, many of which are now available in commercial quantities from Metal & Thermit Corporation, New York, we may mention (1) those in which R is an alkyl or alkylene radical having up to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, isoamyl, t-butyl, hexyl, allyl and vinyl; or (2) in which R is an aryl or aralkyl radical such as phenyl and benzyl; or (3) in which R is a cycloaliphatic radical such as cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl. X is a halogen, such as chlorine, bromine and iodine.

Specific examples of operable Grignards include methyl magnesium chloride, methyl magnesium bromide, methyl magnesium isodide, ethyl magnesium chloride, ethyl magnesium bromide, ethyl magnesium iodide, propyl magnesium chloride, propyl magnesium bromide, propyl magnesium iodide, butyl magnesium chloride, butyl magnesium bromide, butyl magnesium iodide, phenyl magnesium chloride, phenyl magnesium bromide, phenyl magnesium iodide, benzyl magnesium chloride, benzyl magnesium bromide, benzyl magnesium iodide, cyclohexyl magnesium chloride, cyclohexyl magnesium bromide and cyclohexyl magnesium iodide.

In forming the aldehyde (IIIc) any carbonyl-containing compound may be used. Consequently, ketones and aldehydes in general may be employed. For purposes of 4 making ionones substituted in the keto-side chain we recommend that the applicable ketones should have a reactive methylene group, and should conform to the following formula:

where R and R are H or lower alkyl and alkylene groups, aryl, or aralkyl groups having up to 5 carbon atoms in the side chains. Examples of such ketones include methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl butyl ketone, methyl isobutyl ketone, mesityl oxide, methyl t-butyl ketone, ethyl propyl ketone, ethyl isopropyl ketone, and ethyl t-butyl ketone.

The epoxy geranyl acetate (I) or other esters may be formed from the corresponding geranyl ester in the presence of organic peracids. While perphthalic acid is usually utilized in such a process we prefer to use the cheaper and commercially available 40% peracetic acid in acetic acid solution supplied by Becco Sales Corporation, Buffalo, NY. From one to two moles of peracetic acid per mole of geranyl ester is used. We prefer to use one mole since an excess of peracids tends to form the diepoxide. The temperature of the reaction could range from about 0-50 C. We prefer to use about 1025 C. since at lower temperatures the reaction is very slow and at a higher temperature the epoxy group is opened to form a glycol monoacetate. Around about 15-25 C. the reaction is fairly rapid and the epoxidation could be concluded within 1560 minutes of the introduction of the peracetic acid. We also prefer to use sodium acetate from 1 to 5% by weight of the peracetic acid used in order to neutralize any mineral acids, usually present in commercial peracetic acid.

The rearrangement of the epoxy to the keto group is made with strong mineral acids such as sulfuric or perchloric acid. We prefer to use the latter because the yields are better and there is little by-products formed (such as the opening of the epoxide cycle to form glycol or an allylic alcohol). The temperature of the rearrangement could be carried out as high as 50 C. or as low as 0 C. We prefer to work between 10-35 C. since these temperatures are conveniently close to room temperature and the reaction proceeds at a good rate with the least amount of by-products (10-15% A solvent is not necessary but could be used to control the temperature of the reaction and reduce the amount of by-products; ether, benzene, toluene and other water immiscible solvents could be used advantageously. We prefer to use benzene or toluene for this reaction. The saponification of the intermediate keto ester to II is made by conventional means using aqueous or alcoholic alkalies.

The Grignard reaction (II to III) is carried out by treating II with a Grignard reagent, RMgX, in 2 to 4 molar excess. We prefer to use from 2 to 2.5 moles. Such Grignard reagents are now commercially available from Metal & Thermit Corporation, New York, N.Y., in tetrahydrofuran (T.H.F.) solutions. The introduction of the ketoalcohol (II) to the Grignard reagent could be carried out in a variety of solvents such as ether, T.H.F., benzene, toluene, etc. We prefer to work in benzene or toluene solutions. Commercial acetone (moisture below 0.15%) is used for the treatment of the Grignard reaction product although other ketones and aldehydes could be used. In the latter case, of course, the reaction product would be different since the aldehyde IIIc will give different condensation products with the excess carbonyl derivative. Since the hydride transfer involving the alkoxide and the ketone is essentially an equilibrium type of reaction (analogous to the Meerwein- Pondorf reaction), we use from one to ten molar excess of the ketone. We prefer to use three to five molar excess of the ketone, since below the lower limit little hydride transfer reaction takes place, whereas above the higher limit, considerable self condensation of the ketone may take place with the formation of aldols and water, which deactivates the alkoxides and interferes with the hydride transfer. The temperature of the reaction may be carried out between -100 C. We prefer to use the range between 30-60 C. which is close to room temperature and the boiling point of acetone.

The isomerization or cyclization of the ketone condensation product (III) to a d-substituted ionone is carried out in known manner for the condensation of pseudoionone to ionone.

In order to illustrate the invention, and not by way of limitation, we give the following examples:

Example 1.-6,7-epoxydihydrogeranyl acetate 450 ml. of 40% peracetic acid solution (Becco Chemicals) containing 17 g. anhydrous sodium acetate is slowly introduced into a mixture of 435 g. geranyl acetate and 450 ml. benzene containing 17 g. anhydrous sodium acetate. The addition is made within 30-45 minutes under ice water cooling and stirring, the temperature remaining between 10-20 C. After the addition is complete, stirring is continued at room temperature for an additional 2-3 hours. The mixture is then washed twice with 1 volume of saturated sodium chloride solution and then neutralized with 10% soda ash solution and the solvent evaporated. Upon distillation the main part of the reaction product distills at 113 C. at 2 mm. pressure, n 1.4550-1.4555, yield 420-440 g. Saponification value 262.5 (theory 264).

Example 2.6-ketodihydrogeranyl acetate To 150 g. 6,7-epoxydihydrogeranyl acetate and 250 ml. dry benzene in a flask provided with good agitation and ice-water cooling, is added dropwise 1.8 g. HClO 70% within 10-15 minutes and the temperature kept between 10-20 C. After stirring for an additional 5 minutes the mixture is neutralized with 30% NaOH, the solvent evaporated and the reaction product distilled. The main cut B.P. 1091l0 at 2 mm. 7% 14570-14580 amounts to approximately 115 g. and contains about 85% of the keto ester (by oxirnation).

Example 3.-6-ketodihydrogeraniol 315 g. fi-ketodihydrogeraniol acetate, 120 g. KOH, 60 ml. water and 550 ml. ethanol are heated under reflux for one half hour, then 400 ml. aqueous ethanol is distilled oif. The reaction mixture is then treated with two volumes of saturated sodium chloride solution, extracted with benzene and distilled. The main cut distills at 115- 118 C. at 1 mm. 12 1.47401.4750, carbonyl value 90% (by oximation), yield 225-240 g.

Example 4.6,7-ketodihydrogeraniol directly from geranyl acetate To 1108 g. geranyl acetate, 1100 ml. benzene, and 42 g. sodium acetate is added under good agitation, within 2 hours, 1160 g. 40% peracetic acid (Becco) containing 42 g. anhydrous sodium acetate at a temperature ranging from 25-30 C. After completion of the addition, stirring is continued for two more hours at room temperature and the reaction mixture is then washed twice with 2 volumes of sodium chloride saturated solution and finally neutralized with Na CO The benzene is evaporated leaving about 1215 g. of a crude 6,7-epoxydihydrogeranyl acetate.

The crude epoxide is then slowly fed under good agitation into a flask containing 1000 ml. dry benzene containing 3 g. 70% perchloric acid while the temperature is kept at 10-150 C. with an ice-water cooling bath. After the addition of about half the epoxide Within 25 minutes, an additional 1 g. HClO was added, followed by another 2 g. HClO after the feeding of three quarters of the epoxide. The whole addition of the epoxide took about 1 hour and was followed by the final addition of 2 g. HClO and the reaction was completed by stirring for 10 more minutes at 10-15 C. (a total of 8 g. 70% perchloric acid was used).

The reaction flask was then fitted with a distilling head and 600 g. 50% aqueous sodium hydroxide was fed within 2-3 minutes under agitation. The reaction mixture became viscous and warmed up while benzene distilled off. After 15 minutes agitation, 100 ml. Water was added and the flask heated to distill off the remaining solvent. An additional 100 ml. water was added to dissolve the crystalline salts and the reaction mixture heated under reflux for an additional half hour. The top layer was separated, washed with NaCl saturated solution, slightly acidified with acetic acid and distilled. The main 6-ketodihydrogeraniol distilled at about 115-120 C. at 1 mm. pressure n 1.4740-1.4750, yield: 470-520 g., carbonyl value (by oximation), a higher boiling cut -B.P. 130-135 C. at 1 mm. n 14840-14860 (75-90 g.) consisted of the 3,7-dimethyl-2-7-dien-1-6-diol.

Example 5.6,9,lO-trimethyl-9-hydroxyundeca- 3-5-dien-2-one To a Grignard reagent prepared from 255 g. methyliodide (1.8 m.) in 300 ml. ether and 45 g. magnesium (1.8 m.) in ml. ether, was added under ice-water cooling and stirring, 127.5 g. 6-ketodihydrogeraniol (0.75 m.) in 300 ml. dry benzene. After the addition was completed heating was started and the reaction temperature brought to about 60-70 C. by distilling off the major part of the ether. The heating and stirring was continued for one and a half hours more. The reaction mixture became viscous and was finally cooled to room temperature by means of an ice-water bath. 500 ml. of dry acetone (moisture content 0.11%) was slowly added within 15-20 minutes under strong agitation and cooling. The Grignard reaction product which dissolved as a clear amber solution was heated under agitation and refluxed. After about half an hour a rich precipitate of basic magnesium salt formed and after two hours reflux heating was discontinued and the reaction mixture left overnight at room temperature. A solution of 130 m1. acetic acid and 260 ml. water was then added to dissolve the magnesium salts and the excess acetone distilled until the pot temperature reached 100- C. 150 ml. water was added to the reaction mixture to dissolve the crystalline salts and the top layer separated. After extraction with 100 ml. benzene, the top layers were combined, washed with water and the solvent evaporated. Upon distillation some water of dehydration of the aldolization products was collected followed by acetone condensation products (mesityl oxide, diacetone alcohol etc.) and a main cut (30%) consisting of 3,6,7- trimethyl-Z-octen-1-6-diol (1119.), RF. -130" C. at 1 mm. 11 1.4840-1.4850; followed by a major cut (40- 45%) of 6,9,10 trimethyl 9hydroxy-undeca-3-5-dien-2- one. B. P. -145 C. at 1 mm. 11 1.5250, 2,4-dinitrophenylhydrazone M. P. 177178 C.

Example 6.Alpha-irone 4 g. of 6,9,10-trirnethy1-9-hydroxy-undeca-3-5-dien-2- one (III) was mixed with 18 g. 85% H PO at 30 C. and the temperature maintained between 30-40 C. The reaction mixture was then decomposed with 100 ml.- water and extracted with 25 ml. benzene. After washing with a saturated NaCl solution, the benzene was evaporated and the alpha-irone mixture distilled at 85-95 C. at 1 mm. yielding 3 g. 11 1.4980 possessing the characteristic violet odor of alpha-irone. The gas liquid chromatography on a 20 M Carbowax column showed the product to consist of a mixture of Percent Neo alpha-irone 18.5 Neo iso alpha-irone 71.5 Beta-irone 10 The mixture was almost identical with a product obtained, under the same conditions, from an authentic sample of pseudo-irone. A 4-phenylsemicarbazone M.P. 174 was isolated from the mixture which gave no melting point 7 depression with an authentic sample prepared from neo iso alpha-irone. Example 7.-6,l-dimethyl-9-ethyl-9-hydroxyundeca-3,5-

diene-2-one To 1 mole of ethyl magnesium bromide prepared in the conventional way from 1 mole of ethylbromide (110 g.), 1 mole of magnesium (24.4 g.) in 250 ml. dry ether was added under ice water cooling 0.4 mole (68 g.) of 6-ketodihydrogeraniol in 200 m1. dry benzene within one half hour. The reaction mixture was then heated and the ether evaporated until the reaction temperature reached 60 C. and then refluxed for two and one half hours. After cooling at room temperature 300 g. of dry acetone were slowly added under stirring and cooling within 20- 30 minutes and the reaction mixture which formed a clear solution was refluxed for 4 hours under agitation, whereby a rich precipitate of magnesium salts formed. After cooling the reaction mixture was poured into a solution of 65 ml. acetic acid in 130 ml. of water containing 100 g. ice. The excess acetone was evaporated and the oily layer was separated. The mother liquors were extracted with 50 ml. benzene and the combined organic layers washed with saturated NaCl solution. Upon distillation there was collected about 40-45 g. of 6,lO-dirnethyl-9-ethyl-9-hydroxy undeca-3,5-diene-2-one boiling at 145-15S C. at 1 mm. n 1.5010. A small amount of approximately 2025 g. of 3,7-dimethyl-6-ethyl-2-octen-l,6-diol boiling at 120- 125 C. at 1 mm. n 1.47401.4755 was obtained as a light distillation cut.

Example 8.6-ethylionones g. of 6,10-dimethyl-9-ethyl-9-hydroxyundeca-3-5-diene-2-one as obtained in Example 7 in 10 ml. benzene were mixed with 50 g. 85% phosphoric acid heated to 50 C. under agitation for 1-1.5 hours. The reaction mixture was then quenched into 250 ml. water, the oil separated and the mother liquor extracted with ml. benzene. After washing the organic layer with saturated NaCl solution the solvent was evaporated and the 6-ethylionone mixture was distilled at 120-125 C. at 1 mm. n 1.4950- 1.4985 (6-8 g.). It consisted of a mixture of four isomers in the approximate proportions of 20:35:25 :15. Analysis calculated for C H O: C:8l.77; H=l0.97. Found: C=82.03; H=10.95. The odor was very flowery and pleasant with an iris note which persisted over 2 weeks on the smelling paper whereas the alpha-irone sample lasted less than 48 hours.

As will now be understood by those skilled in the art, the process described in the foregoing examples may be employed to form other 6-substituted ionones, including those having substituents in the side chain containing the carbonyl group. Thus, by stubstituting an equivalent amount of ethyl magnesium bromide for the methyl magnesium iodide used in Example 5, 6-ethyl ionone can be obtained upon cyclization in accordance with Example 6. In similar manner, 6-propyl ionone, and 6-butyl ionone are obtained by substituting the corresponding propyl magnesium iodide and butyl magnesium iodide, respectively, for the methyl magnesium iodide of Example 5. Side chain substituted 6-substituted ionones are obtained by substituting ketones such as methyl ethyl ketone, di-

ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl butyl ketone, methyl isobutyl ketone, mesityl oxide, methyl t-butyl ketone, ethyl propyl ketone, ethyl isopropyl ketone, ethyl t-butyl ketone for the acetone employed in Example 5.

The foregoing illustrates the practice of this invention which, however, is not to be limited thereby, but is to be construed as broadly as permissible in view of the prior art and limited solely by the appended claims.

We claim:

1. A process, which comprises reacting, at a temperature within the range from about 0 C. to C. a compound having the following formula:

I CHzOH with at least twice the molar amount of a Grignard reagent having the formula:

where R is a member selected from the group consisting of lower alkyl radicals and lower alkylene radicals having up to 6 carbon atoms, phenyl, benzyl and a cycloalkyl groups and X is a halogen and treating the resulting reaction product with at least twice the molar amount of a ketone having the formula: RCH COCH R where R and R are selected from the group consisting 'of H, lower alkyl, lower alkylene, phenyl and aralkyl groups having up to 5 carbon atoms in the side chains.

*2. The process of claim 1, wherein RMgX is methyl magnesium halide, and the ketone is acetone.

3. The process of claim 1, wherein R is methyl, X is iodine, and the ketone is acetone.

4. The process of claim 1, wherein RMgX is ethyl magnesium halide, and the ketone is acetone.

5. The process of claim 1, wherein R is ethyl, X is bromine, and the ketone is acetone.

6. The process of claim 1, wherein RMgX is propyl magnesium halide, and the ketone is acetone.

7. The process "of claim 1, wherein R is propyl, X is bromine, and the ketone is acetone.

8. The process of claim 1, wherein RMgX is butyl magnesium halide, and the ketone is acetone.

9. The process of claim 1, wherein R is butyl, X is bromine, and the ketone is acetone.

References Cited UNITED STATES PATENTS 3,117,982 1/1964 Barton et al. 260-587 LEON ZITVER, Primary Examiner.

M. M. JACOB, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,439,02 Dated April 15, 1969 Inventor(s) Emile H. Eschinasi et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 20, column 3, line 53 and claim 1, lines 26 and 32 "Alkylene" should read Alkenyl Column 2, line 53, "o,9diemthyl-" should read 6,10-dimethy1- Column 3, line :2, "CHOR should read Column 4, line 6, "Alkylene" should read Alkenyl line 12; delete "mesityl oxide" Signed and sealed this 21st day of November 1972 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents