JPH0564146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to dihydrofuran derivatives and certain 2,4,5-substituted-
The present invention relates to 2,3-dihydrofuran and a method for isomerizing cyclopropyl ketone to 2,3-dihydrofuran. More particularly, this method describes the use of 2,4,
It involves catalytic rearrangement (isomerization) to 5-substituted-2,3-dihydrofuran. The use of synthetic fragrance substances has added a new dimension to the field of perfume formulation. As a result of the development of novel synthetic fragrance compounds, fragrance manufacturers have greater flexibility in developing fragrance formulations and are better able to mimic natural fragrances. However, as synthetic substances have become more utilized by fragrance manufacturers in the development of delicate fragrance formulations and the subtle nuances typically associated with natural fragrances, there has been an increase in demand for new synthetic fragrance compounds. There is a demand for one side. Furan derivatives are known to have desirable aroma and flavor properties. For example, ethylfuroate, η-amylfuroate, ethylfuryl β-
Hydroxypropionate and furfural have been reported for use in fragrances, cosmetics, and soaps. Furfuryl alkyl and aryl ethers are disclosed as flavor enhancers in US Pat. No. 3,940,502. Tetrahydrofuran has also been disclosed for use as a flavoring agent. US Pat. No. 3,668,314 discloses the use of esters or ethers of tetrahydrofuran as perfume ingredients in detergent compositions. 3
-Oximino-4-oxo-2,5-dimethyltetrahydrofuran is described in US Pat. No. 4,116,982 and is disclosed to have a fine carmela-like aroma which can be used in the manufacture of fragrances and spices. U.S. Pat. No. 3,470,209 discloses 3-acetonyl-3,5-dimethyl-5-isopropyl-tetrahydrofuran as having a pleasant fragrant aroma reminiscent of laurel and eucalyptus. 2-(1'-hydroxymethyl-
Ethyl)-5-methyl-5-vinyl-tetrahydrofuran is disclosed in US Pat. No. 3,764,567 as an active ingredient for inclusion in floral perfumes.
In U.S. Patent No. 3,227,731, 1-(α-furyl)-2,
Carbonates of 2-dialkyl-1,3-dihydroxypropane and 1-(α-tetrahydrofuryl)-2,2-dialkyl-1,3-dihydroxypropane have been shown to be useful as perfume compounds. 2, which has a vinyl group at the 2-position, a lower carboxylate group at the 4-position and a methyl group at the 5-position;
3-dihydrofurans are Chemical Abstracts,
Volume 75 87758y (1971); Volume 93 71095r (1980);
93239112v (1980); reported in Volume 94, 15458v (1981). Konogai Chemical Abstracts Volume 96
52099r (1982) describes 2,3-dihydrofurans with substituents obtained by oxidative addition of 1,3-dicarbonyl compounds with dienes in the presence of manganese acetate () and copper (). It has been reported. The reported 2,3-dihydrofuran is 5-
None have a higher alkyl group substituted at the position, and there is no suggestion that any of these compounds have useful aromatic properties. The method for producing dihydrofuran with substituents is
U.S. Patent No. 4,180,446 to Schmidt;
No. 4198341; No. 4198342 and No. 4198343. This method uses β-alkoxycrotonic acid ester or 3,3-bisalkoxybutyric acid ester and 1,1,1-trihalogen-4-methyl-3-
It involves a reaction with penten-2-ol or 1,1,1-trihalogen-4-methyl-4-penten-2-ol in the presence of an acid catalyst. 2,4,4-trimethyl-3-carbalkoxy-5-(β,β-
Vinyl dihalogen)-4,5-dihydrofuran is produced in this process. Alonso et al. described the rearrangement of cyclopropyl ketone to 4,5-dihydrofuran using aluminum oxide at room temperature in J.Org.Chem . , 45 , 4530−4532 (1980)
has been reported. The rearrangement is carried out by passing a neutral alumina column through a solution of cyclopropyl ketone in chloroform. dihydrofuran Even if a nearly quantitative yield of 24 to 72
Hours of contact time is required. Tischenko et al. [ Chemical Abstracts , 94 , (1981), 15229w]
describes the ring opening of 1-acetyl-2,2-dichlorocyclopropane in the presence of sodium alcoholate. Depending on the amount of sodium alcoholate used, dihydrofuran or alkynes are formed. Dihydrofuran is also a byproduct of the reaction of 1,4-dichlorobutene-2 with sodium ethyl acetylacetate in alcoholic solution.
Bull.Soc.Chim.France by Bahurel et al., 1971
(6), 2203-8. Fayter,
U.S. Pat. No. 4,252,739 to Jr et al. describes a phase-transfer process for the preparation of vinylcyclopropane derivatives using an onium catalyst and reacting an alkylating agent with an activated methylene compound in the presence of an alkali metal compound and water. are doing. Even if alkylation of the activated carbon atom is predominant, up to about 15% dihydrofuran may be used if the activated methylene compound contains an acyl moiety, such as ethyl acetoacetate. By-products will be obtained as a result of alkylation of the oxygen atom of the acyl group. Dihydrofuran is produced from acid or light rearrangement by McGeer et al., Can.J.Chem . , 51 (10),
1487−93 (1973); Armitage et al., J.Am.Chem.
Soc. , 81 , 2437 (1959); Wilson, J.Am.Chem.
Soc. , 69 , 3002-3 (1947); and Dauben et al., J.
Org.Chem. , 34 , 2301-6 (1969). Although it is known that dihydrofuran can be obtained from cyclopropyl ketone, it is clear from the above literature that various other rearrangement products are formed depending on the reaction conditions used. It would therefore be highly desirable if other processes were available that could specifically obtain dihydrofurans by rearrangement of cyclopropyl ketones. The present invention is based on the general formula [However, R is ethyl or vinyl salt, and R ₂
is a C _1-4 alkyl group and R ₁ is a C _3-10 alkyl group]
A fragrance composition containing dihydrofuran is provided. 2,4,5-tri-substituted-2,3 with the formula
- Dihydrofuran is useful as an aromatic compound for a variety of applications and has the general formula [However, R is an ethyl or vinyl group, and R ₂
is an alkyl group having 1 to 4 carbon atoms, and R ₁ is an alkyl group having 3 to 10 carbon atoms. R ₂ can be a straight-chain or branched group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl and sec-butyl. The alkyl group R ₁ can be straight chain or branched. Compounds exemplifying the above definitions include 4-carbomethoxy-5-n-pentyl-2-
Vinyl-2,3-dihydrofuran; 4-carbetoxy-5-n-pentyl-2-vinyl-2,3-dihydrofuran; 4-carbetoxy-5-n-pentyl-2-ethyl-2,3-dihydrofuran ; 4-carbethoxy-5-(3-thimel-butyl)
-2-vinyl-2,3-dihydrofuran; 4-carbethoxy-5-(3-thymer-butyl)
-2-ethyl-2,3-dihydrofuran; 4-carbetoxy-5-(4-methyl-3-pentenyl)-2-ethyl-2,3-dihydrofuran; 4-carbethoxy-5-(4-methyl- 3-pentenyl-2-ethyl-2,3-dihydrofuran; 4-carboisopropoxy-5-isopropyl-2-vinyl-2,3-cyhydrofuran; 4-carboisopropoxy-5-isopentenyl-2-ethyl- In view of its highly desirable aromatic properties, particularly useful 2,4,5-trisubstituted-2,3-dihydrofurans are those in which R is ethyl or vinyl and R ₂ is methyl. or ethyl, and R ₁ is C _3-8 alkyl. The 2,3-dihydrofurans of the invention are generally characterized by having a pleasant natural aroma. By changing it in various ways, you can create various natural odors (fragrances), for example,
It can imitate herbaceous, green, nutty, fruity or vegetable aromas. In most cases, several of these notes will be present (at the same time) in a fragrance, although one note is often stronger. The aroma is intense but not overpowering, and has good spread rate, stability and dryness. 2,4,5-trisubstituted-2,3-dihydrofurans are used in the production of aromatic products such as perfumes, shampoos, deodorants, shaving creams and gels, body lotions and creams, detergents and bar soaps, etc. and compounds useful in formulation preparation. These 2,4,5-tri-substituted-2,
3-dihydrofuran can be used as the sole fragrance, but is most commonly used in combination with other fragrances. When combined with other fragrances, 2,3-dihydrofuran may be present in trace amounts up to about 50% of the fragrance formulation, depending on the particular fragrance desired and the intended use of the final product. The process of the invention generally relies on catalytic isomerization,
The present invention relates to the preparation of 2,3-dihydrofuran from the corresponding cyclopropyl ketone compound. More particularly, an onium compound of 1,1-disubstituted-2-alkylcyclopropane or 1,1-disubstituted-2-alkenylcyclopropane in which one of the substituents at position 1 is an acyl group is used as a catalyst. ,2,
Concerning rearrangement (isomerization) to 4,5-substituted-2,3-dihydrofuran. By this method, a wide variety of 4,5-disubstituted-2-alkyl (or alkenyl)-2,3-dihydrofurans can be easily obtained. Using the process of the invention, it is also possible to treat products containing a mixture of vinylcyclopropane and dihydrofuran moieties to increase the amount of dihydrofuran. The method of the invention uses 1,1-disubstituted-2-hydrocarbylcyclopropanes in which one of the substituents in position 1 is an acyl group. Here, it is also called cyclopropyl ketone compound 1,
1-Disubstituted-2-hydrocarbylcyclopropane has the general formula [wherein R and R ₁ are hydrocarbon groups having 1 to 24 carbon atoms and X is a carboxylate, nitrile, amide or sulfonyl group]. From this formula, it is clear that a wide variety of cyclopropyl ketones can be used in the method for producing 2,3-dihydrofuran of the present invention. The process of the present invention further encompasses the various geometric and stereoisomeric forms of these cyclopropyl ketones, as well as mixtures and racemates thereof. a hydrocarbyl group from which R ₁ is selected;
That is, a group consisting only of carbon and hydrogen can be aliphatic, cycloaliphatic or aromatic. If R ₁ is an aliphatic group, it may be straight-chain or branched, saturated or unsaturated and preferably contains 1 to 12 carbon atoms. Unsaturated aliphatic groups will normally have no more than one double bond per four carbon atoms. Useful cycloaliphatic groups from which R ₁ is selected may contain from 3 to 24 carbon atoms, but
However, preferred cycloaliphatic groups have 5 to 20 carbon atoms and have the formula [However, m is an integer of 0 to 8, and more preferably 0 to 4, and A is a non-aromatic 5-membered
or represents a 6-membered carbocyclic ring system, and r' and r'' correspond to hydrogen, C _1-8 alkyl, C _1-8 alkyl, phenyl or benzine. Particularly preferred cycloaliphatic groups are [Formula] The moiety is an unsubstituted or mono-C _1-8 alkyl- or alkynyl-substituted cyclopropyl, cyclopentenyl, cyclo-hexyl, cyclohexenyl or cyclohex-2,4-dienyl group; If R ₁ is an aromatic hydrocarbon group, it will contain from 6 to 24 carbon atoms and may be substituted with one or more hydrocarbon groups. may consist of a single ring or a fused ring system.
Particularly useful aromatic groups contain 6 to 18 carbon atoms and have the formula [where m, r' and r'' are the same as defined above for cycloaliphatic]. Preferred aromatic groups include phenyl, C _1-8 alkyl- or alkenyl-substituents. phenyl, benzine and
C _1-8 benzyl with an alkyl- or alkenyl-substituent. The ring may also contain other substituents, such as halogen, hydroxy, alkoxy, carboxy,
carboxylates, etc. The hydrocarbyl group R containing 1 to 24 carbon atoms can be an aliphatic, cycloaliphatic or aromatic group of the general type mentioned above for R ₁ .
Most commonly, however, R is a C _2-8 aliphatic group, which may be straight chain or branched, and may be saturated or unsaturated. If R is unsaturated, it will not have more than one double bond. Vinyl and vinylene groups are particularly useful unsaturated aliphatic groups. The process of the invention is particularly effective for the isomerization of cyclopropyl ketones where R is vinyl or ethyl. X is of the formula -C≡N, [Formula] and [Formula], respectively, where R ₂ , R ₄ and R ₅ are hydrocarbyl groups as defined above for R ₁ and R ₃ is hydrogen or a hydrocarbyl group as defined above for R ₁ ]. The hydrocarbyl group selected from R ₂ , R ₃ , R ₄ and R ₅ is C _1-4 alkyl, phenyl,
The cases of phenyl, benzyl with C _1-4 alkyl substituents or benzyl with C _1-4 alkyl substituents are particularly useful in the present invention. In the method of the invention, cyclopropyl ketone is isomerized by heating in the presence of an onium catalyst. This reaction has the general formula: [However, X, R and R ₁ are the same as defined above]. The temperature for the reaction will range from about 60°C to 200°C, and best results will range from about 80°C to 170°C.
obtained at a temperature of The onium catalyst is used in an amount of about 0.5 to 20% by weight of the cyclopropyl ketone. Most commonly about 2 to 15% by weight of onium catalyst is present. Although not necessary for the reaction, it may be advantageous if there is a use of a solvent or diluent. For example, when cyclopropyl ketone is a solid or viscous fluid, handling of the raw material can be facilitated by dissolving it in a small amount of a suitable solvent or diluent.
The solvent/diluent should be inert under the conditions used for the reaction and should not react with the cyclopropyl ketone, 2,3-dihydrofuran or onium catalyst. It is also preferred that the solvent has a boiling point above the reaction temperature. Although low boiling point solvents can also be used,
In this case, it is necessary to use a closed container (autoclave) or the like. When the product is separated (recovered) by distillation, the boiling point of the solvent is such that it is easily
It must be able to be separated from 3-dihydrofuran and the completed, unreacted cyclopropyl ketone. Useful solvents used in the method of the invention/
Diluents include dimethyl sulfoxide; dimethyl sulfolane; sulfolane; dimethylformamide; N
-Methyl-2-pyrrolidone; hexamethylphosphoramide; triglyme and the like. In a preferred embodiment of the invention, the onium catalyst is dissolved in cyclopropyl ketone and the reaction is carried out in the absence of other materials, ie, without additional solvents or diluents. Onium compounds useful as catalysts for this invention have at least 6 carbon atoms and have the formula [However, M is nitrogen or phosphorus, and R ^* is 1 to
represents a hydrocarbon group having 22 carbon atoms and A is halide, preferably chloride or bromide], and quaternary ammonium and phosphonium compounds are included. hydrocarbon group
R ^* may be the same or different and may be an alkyl group (which can be saturated, unsaturated, branched or straight chain), phenyl, phenyl with a C _1-4 alkyl substituent, benzine or C _1-4 alkyl Contains benzyl with substituents. Particularly useful onium catalysts contain at least 10 carbon atoms. Exemplary onium compounds that can be used as catalysts for the process of the invention include: tetrabutylammonium chloride, tetrabutylammonium bromide; dimethyldibenzylammonium chloride; dimethyldibenzylammonium bromide; trimethylbenzylammonium chloride; trimethylbenzylammonium bromide Tricaprylylmethylammonium chloride; Tricaprylylmethylammonium bromide; Tributylhexadecylphosphonium chloride; Tributylhexadecylphosphonium bromide; and the like. The cyclopropyl ketone used in the process of the invention must be essentially free of water and caustic.
For this reason, cyclopropyl ketones obtained by classical or phase transfer condensation are
Perform normal processing to remove water, caustic and inorganic salts. For example, if cyclopropyl ketone is obtained by the phase transfer method of U.S. Pat. The salt may be dissolved in water and then the organic and aqueous phases may be separated. Residual caustic compounds can be neutralized with dilute acids prior to dissolution of the peroxide or salt. The resulting organic phase, treated as described above, may then be treated with a desiccant to remove water. Most commonly, however, the organic phase is stripped or distilled under reduced pressure to remove the water and organic solvent present therein. Example 1 Methyl 1-acetyl-2-vinylcyclopropane-1- is produced by reaction of 1,4-dichlorobutene-2 with methyl acetoacetate using a classical condensation method.
A carboxylate was produced. In that reaction, first
Methyl natriacetoacetate was produced by reacting 36.6 g of sodium metal with 500 ml of anhydrous methanol and then adding 185.6 g of acetoacetic acid methyl ester. The resulting solution was then added dropwise to 100 g of 1,4-dichlorobutene-2 in 200 ml of methanol solvent under a nitrogen atmosphere at a rate sufficient to maintain reflux. Refluxing was continued for 3 hours after the addition was complete and then stirred overnight at ambient temperature. After filtration to remove insoluble salts, the resulting reaction product (IA) was stripped under reduced pressure. Fractional distillation yields the preeminently desired vinylcyclopropane product [boiling point 83.5
-85.0°C (4.5 mmHg); n _D ²² °1.4705], and the product (IB) was obtained in 55% yield. Nuclear magnetic resonance spectroscopy and gas chromatography analysis of IB revealed that the products were 85.7% methyl 1-acetyl-2-vinylcyclopropane-1-carboxylate and 14.3% 4-carbomethoxy-5-methyl-2-vinyl-
It was shown that it consists of 2,3-dihydrofuran. To illustrate the rearrangement reaction, 2 g of IB was mixed with 0.24 g of tricaprylylmethylammonium chloride and heated at 100°. After 20 hours, methyl 1-acetyl-2-vinylcyclopropane-1-carboxylate had decreased to 11.6%. The majority of the product (76.3%) is 4-carbomethoxy-5-methyl-
It was confirmed to be 2-vinyl-2,3-dihydrofuran. When heated for an additional 20 hours, 4-carbomethoxy-5-methyl-2-vinyl-
The amount of 2,3-dihydrofuran increased to 83.3%. When IB was heated alone for 20 hours, methyl 1-
The amounts of acetyl-2-vinylcyclopropane-1-carboxylate and 4-carbomethoxy-5-methyl-2-vinyl-2,3-cyhydrofuran were 85.4% and 14.6%, respectively, with essentially no change occurring. Ta. In a closed reactor (autoclave),
Heating IA for 2 hours at 100 °C is essential for the relative proportions of methyl 1-acetyl-2-vinylcyclopropane-1-carboxylate and 4-carbomethoxy-5-methyl-2-vinyl-2,3-dihydrofuran. No change was made. Example 2 2 g of product IB are mixed with 0.16 g of dibenzyldimethylammonium chloride and the mixture is heated to 100°C.
heated with. As confirmed by nuclear magnetic resonance spectroscopy and gas chromatography analysis, the rearrangement product obtained after 20 hours was 74.5% 4-carbomethoxy-
It was confirmed that it contained 5-methyl-2-vinyl-2,3-dihydrofuran and 25.2% of methyl 1-acetyl-2-vinylcyclopropane-1-carboxylate. Example 3 Product IB (2 g) was mixed with 0.30 g of tri-n-butylhexadecylphosphonium bromide and the mixture was heated at 100<0>C. After 7 hours, the 1-acetyl- present in the mixture
The amount of 2-vinylcyclopropane-1-carboxylate was reduced to 52% and 44% of 4-carbomethoxy-5-methyl-2-vinyl-2,3-
Dihydrofuran was present. When heating was continued for an additional 12 hours, the amount of 4-carbomethoxy-5-methyl-2-vinyl-2,3-dihydrofuran in the mixture was approximately
increased to 75%. Example 4 To demonstrate the criticality of the catalyst for rearrangement, Example 3 was repeated using tetramethylammonium bromide in the same mole percent instead of tri-n-butylhexadecylphosphonium bromide. After heating at 100℃ for 20 hours, 4 in the mixture
-carbomethoxy-5-methyl-2-vinyl-
The amount of 2,3-dihydrofuran remained essentially unchanged. Example 5 Substantially pure 1-acetyl-2-vinylcyclopropane-carboxyanilide (melting point 104°C-104.7
C) was obtained by recrystallization from isopropanol and rearranged to 4-carboxyanilide-5-methyl-2-vinyl-2,3-dihydrofuran by the method of the invention. In this reaction, 0.5 g of 1-
Acetyl-2-vinylcyclopropanecarboxyanilide was mixed with 8.9 mg of tricaprylylmethylammonium chloride and heated at 100°C for 1 hour. Analytical results showed approximately 70% conversion of 1-acetyl-2-vinylcyclopropanecarboxyanilide to 4-carboxyanilide-5-methyl-2-vinyl-2,3-dihydrofuran. Reheating further increased the amount of 4-carboxyanilide-5-methyl-2-vinyl-2,3-dihydrofuran formed. 62mg as catalyst
When this reaction is repeated using tetrabutylammonium chloride of
80% conversion of vinyl-2,3-dihydrofuran was achieved. 1-acetyl- without onium catalyst
2-vinylcyclopropanecarboxyanilide
No dislocation was observed when heated at 100°C. Example 6 By the phase transfer method of U.S. Pat. No. 4,252,739,
Ethyl 2-vinyl-1-
Hexanoylcyclopropane-1-carboxylate was obtained. The reaction was carried out in a mixture of water and methylene chloride using 0.0133 mol of tricaprylylmethylammonium chloride as a phase transfer catalyst.
The resulting reaction product was then passed through a sintered glass funnel to remove excess sodium hydroxide and insoluble salts formed during the reaction, and neutralized using 10% sulfuric acid. The crude product obtained after drying and removal of methylene chloride contained approximately 95% ethyl 2-vinyl-1-hexanoylcyclopropane-1-carboxylate. Ethyl 2-vinyl- obtained above (120 g)
1-hexanoylcyclopropane-1-carboxylate was mixed with 25.6 g of tricaprylylmethylammonium chloride and heated to 110°C under a nitrogen atmosphere with stirring to convert the cyclopropyl ketone into the corresponding 2,3-dihydrofuran. became isomerized.
After 3 hours, the results of gas chromatography analysis showed that
The reaction mixture was 41% 4-carbethoxy-5-n-
It became clear that it contained pentyl-2-vinyl-2,3-dihydrofuran. 4-carbethoxy-5-n-pentyl-2-vinyl-2,3
- 110°C until dihydrofuran content increases to 87%
Continued heating. Almost pure 4-carbethoxy-5-n-pentyl-2-vinyl by distillation
It was possible to obtain 2,3-dihydrofuran. 4-carbethoxy-5-n-pentyl-2-
Vinyl-2,3-dihydrofuran was a clear, colorless liquid (BP 103-109°C @ 2mmHg; nD ²⁵ ° 1.4709) with a pleasant aroma useful in diasmone and/or trans formulations. nmr( _CDCl3 )σ1.28(t,3H( _CH3 - _CH2 -O-
CO);4.23(q,2H( _CH3 - _CH2 -O-CO-));
0.90(t, 3H( _CH3 - _CH2 - _CH2 )); 1.10-1.80
(m, 6 methylene H); 2.50-3.55 (m, 2-ring methylene H); 2.70 (br.t., (2 methylene H. (adjacent to the ring)); 4.80-5.55 (m, 3 vinyl H), 5.70−6.34
(m, I ring H). IR (Film) 2960, 2930, 2870, 1695,
1637, 1370, 1252, 1225, 1173, 1104, 1050,
970 and 767 cm ^-1 . Example 7 4-carbetoxy-5-n-pentyl-2-vinyl-2,3- prepared according to the method of Example 6
Hydrogenating dihydrofuran to form 4-carbethoxy-
5-n-pentyl-2-ethyl-2,3-dihydrofuran was obtained. In this reaction, 13 g of 4-carbetoxy-5-n-pentyl-2-vinyl-2,
Parr 3-dihydrofuran and 75 ml of ethyl acetate.
into the reactor of the device. The system was thoroughly purged with nitrogen and 0.65 g of hydrogenation catalyst (5% Pd on carbon) was added under a nitrogen atmosphere. Furthermore, perform a nitrogen purge,
Shaking was started and the system was pressurized to 15 psig with hydrogen. The system was pressurized as necessary until no more hydrogen absorption was observed. The reaction mixture was then passed through Dicalite to remove the Pd/carbon catalyst;
Ethyl acetate was removed under reduced pressure. Gas chromatographic analysis showed 98% yield of crude 4-carbethoxy-5-n-pentyl-2-ethyl-2,3-dihydrofuran. The crude product was subjected to rectification using a rotating band rectifier to obtain essentially pure 4-carbethoxy-5-n-pentyl-
2-ethyl-2,3-dihydrofuran (BP112
−114° @ 1 mmHg; n _D ²⁵ ° 1.4636), which was confirmed by nuclear magnetic resonance absorption (nmr) and infrared (IR) spectroscopy. nmr( _CDCl3 )σ1.29(t,3H( _CH3 - _CH2 -O-
CO−));4.19(q,2H( _CH3 − _CH2 −O−CO
−)); 0.60−1.95(m, 14H(−CH ₂ − CH ₂ and
_CH3 - _CH2 -type H)); 2.30-3.42 (m, 2-ring methylene H); 2.68 (br.t., (2-methylene H [adjacent to the ring])); 4.30-4.95 (m, 1 Ring H). IR (Film) 2970, 2930, 2870, 1694,
1636, 1462, 1370, 1330, 1255, 1228, 1173,
1104, 1048, 973 and 765cm ^2-1 . 4-Carbethoxy-5-n-pentyl-2-ethyl-2,3-dihydrofuran had a suitable and appropriate note for the formulation of diasmone and citrus compositions. Example 8 In a manner similar to that described in Example 6, ethyl 2-vinyl-1-(4-methylpentanoyl)
4-carbethoxy-5-(3-methyl-
Butyl)-2-vinyl-2,3-cyhydrofuran was produced. For this reaction, 125 ml of ethyl 2-vinyl-1-(4-methylpentanoyl)cyclopropane-1-carboxylate was mixed with 25.4 g of tricaprylylmethylammonium chloride. This mixture was stirred at 100° C. for approximately 11 hours.
Subsequent gas chromatographic analysis showed that the reaction mixture contained approximately 85% 4-carbethoxy-5-(3
-Methyl-butyl)-2-vinyl-2,3-dihydrofuran. Heating was removed and the crude product was rectified using a rotating band rectifier equipped with a 12 inch column. almost pure 4
-carbethoxy-5-(3-methyl-butyl)-2
-vinyl-2,3-dihydrofuran (BP101-
dn _D ²⁵ °1.4742) was obtained. 4-
Carbethoxy-5-(3-methyl-butyl)-2-
Vinyl-2,3-dihydrofuran had a pleasant aroma with a somewhat weedy, fatty, nutty Scotch whiskey aroma profile. nmr( _CDCl3 )σ1.27(t,3H( _CH3 - _CH2 -O-
CO−));4.23(q,2H( _CH3 − _CH2 −O−CO
−));0.90(d,6H( _CH3 ) ₂ −CH));1.22−1.82
(m, 3H(−CH ₂ − CH ₂ − CH −)); 2.68(br.t,
2H (2 methylene H [adjacent to the ring])); 2.40−3.40 (m,
2-ring methylene H); 4.85-5.60 (m, 3 vinyl H); 5.78-6.40 (m, 1-ring H). IR (Film) 2959, 2930, 2875, 1699,
1636, 1369, 1311, 1250, 1234, 1192, 1172,
1135, 1107, 1054, 970 and 765 cm ^-1 . Example 9 4-carbetoxy-5- obtained by the method of Example 8
(3-Methyl-butyl)-2-vinyl-2,3-dihydrofuran was hydrogenated and 4-carbethoxy-5
-(3-methyl-butyl)-2-vinyl-2,3-
Dihydrofuran was obtained. The hydrogenation method used is the same as described in Example 7. After removing the catalyst and ethyl acetate, 17.47 g of crude 4-carbethoxy-5-(3-methyl-butyl)-2-ethyl-
2,3-dihydrofuran was obtained. Rectification of the crude hydrogenation product yields nearly pure 4-carbethoxy-5-(3-
Methyl-butyl)-2-ethyl-2,3-dihydrofuran (n _D ²⁵ °1.4621) was obtained. This material had a rich fruity aroma - mainly strawberry and apples, with traces of chamomile. nmr( _CDCl3 )σ1.28(t,3H( _CH3 - _CH2 -O-
CO−));4.21(q,2H( _CH3 − _CH2 −O−CO
−));0.93(d,6H( _CH3 ) ₂ −CH−));0.71−
1.86 (m (complex), 8H; 2.68 (br.t, 2H
(2 methylene H [adjacent to the ring])); 2.26−3.31 (m, 2
Ring methylene H); 4.28-5.01 (m, 1 ring H). IR (Film) 2980, 2955, 2900, 1705,
1640, 1472, 1375, 1340, 1265, 1240, 1175,
1145, 1110, 1055, 970 and 770 cm ^-1 . Example 10 Ethyl 2 obtained by condensation of ethyl 5-methyl-4-hexenoyl acetate with 1,4-dichlorobutene-2 under phase transfer conditions in a similar manner to that previously described. -Isomerizing vinyl-1-(5-methyl-4-hexenoyl)cyclopropane-1-carboxylate to 4-carbetoxy-5-(4-methyl-3-pentenyl)-2-vinyl-2,3 -Dihydrofuran was obtained. Isomerization is
It was carried out at 110° under a nitrogen atmosphere using a 19.6% by weight tricaprylylmethylammonium chloride catalyst. After 3 hours, chromatographic analysis showed that 92% of 4-carbetoxy-
The presence of 5-(4-methyl-3-pentenyl)-2-vinyl-2,3-dihydrofuran was confirmed. Rectification of the isomerization product yields 15 g of pure 4-carbethoxy-5-(4-methyl-3-pentenyl)
-2-vinyl-2,3-dihydrofuran (B.
P.104−110℃@0.6mmHg; n _D ²⁵ °1.4910) was obtained. This clear, colorless liquid had a somewhat hawthorn-like aroma with chamomile-like overtones. nmr( _CDCl3 )σ1.30(t,3H( _CH3 - _CH2 -O-
CO−)); 4.25(q, 2H( _CH3 − _CH2 −O−CO
−)); 1.68 (d, 6H ( CH ₃ ) ₂ = CH−)); 2.42 (br.t
，
2H( _-CH2 -CH=C( _CH3 ) ₂ )); 2.75(br.t, 2H
(2 methylene H [adjacent to the ring])); 2.40−3.45 (m, 2
Ring methylene H, partially hidden); 4.85-5.60 (m,
2-ring methylene H); 5.77-6.37 (m, 1-ring H). IR (Film) 2975, 2920, 2875, 1691,
1633, 1447, 1372, 1310, 1232, 1155, 1107,
1065, 1025, 972, 915 and 765 cm ^-1 . Example 11 4-carbetoxy-5-(4-methyl-3-pentenyl)-2-vinyl-2,3-dihydrofuran of Example 10 was hydrogenated to give 4-carbetoxy-5-(4-methyl-3-pentenyl)-2-vinyl-2,3-dihydrofuran.
5-(4-methyl-3-pentenyl)-2-ethyl-2,3-dihydrofuran was obtained. A 5% catalyst by weight (5% Pd on carbon) was used. Hydrogenation was almost complete within 3 hours. After removing the catalyst and ethyl acetate solvent, the crude hydrogenation product was rectified using a 50-stage rotating band rectifier to obtain nearly pure 4-
Carbethoxy-5-(4-methyl-3-pentenyl)-2-ethyl-2,3-dihydrofuran (B.
P.58℃ @0.01mmHg; n _D ²⁵ °1.4791) was obtained. This product had a nutty character and a milder overall odor quality than the unsaturated parent disclosed in Example 10. nmr( _CDCl3 )σ1.28(t,3H( _CH3 -CH-O-
CO−));4.22(q,2H( _CH3 − _CH2 −O−CO
−));0.98(t,3H( _CH3 − _CH2 −C−));1.33−
1.70 (q.2H (CH ₃ − CH ₂ −C−) hidden);
1.68(d, 6H(( _CH3 ) _2C =CH-)); 2.35(br.t,
2H(-CH2 _- CH=C( _CH3 ) ₂ )); 2.73(br.t, 2H
(2 methylene H [adjacent to the ring])); 2.30−3.35 (m, 2
Ring methylene H, partially hidden); 4.30−4.80
(m, 1 ring H); 5.23 (br, t, 1 vinyl H). IR (Film) 2970, 2930, 2875, 1690,
1635, 1450, 1373, 1236, 1156, 1107, 1066,
1026, 985, 830 and 765 cm ^-1 . Example 12 Ethyl 2-vinyl-1
Isomerization of -benzoylcyclopropane-1-carboxylate gave 4-carbethoxy-5-phenyl-2-vinyl-2,3-dihydrofuran. 20% by weight of tricaprylylmethylammonium chloride was used to promote isomerization. The mixture was heated at 150°C for about 2 hours. Here about 7%
Only 1 cyclopropyl ketone remained.
Two rectifications of the resulting isomerized product yield almost pure 4-carbethoxy-5-phenyl-2-vinyl-
2,3-dihydrofuran (BP110℃ @0.1mm
Hg; n _D ²⁵ °1.5570) was obtained. This product had odor characteristics somewhat similar to coumarin. nmr( _CDCl3 )σ1.20(t,3H( _CH3 − _CH2− O
-CO-);4.17(q,2H( _CH3 - _CH2 -O-
CO)); 2.70−3.60 (oct, 2-ring methylene H); 2.93
-5.60 (m, 3 vinyl H); 5.80-6.45 (m, 1 ring H); 7.30-8.15 (m, 5 phenyl H). IR (Film) 2980, 1697, 1622, 1598,
1496, 1446, 1370, 1240, 1085, 1070, 987,
926, 760 and 695 cm ^-1 . Examples 13-14 Various products obtained from phase transfer reactions similar to Examples 8-12 and containing varying amounts of cyclopropyl ketone were rearranged by the method of the present invention. The products of the phase transfer reaction (used in the rearrangement reaction) were neutralized and essentially free of insoluble salts, water and inorganic solvents. Tricaprylylmethylammonium chloride was used as catalyst for all rearrangement reactions. Cyclopropyl ketone and the corresponding 2,3-
Some details of these and previously described reactions, including the amount of dihydrofuran, are shown in Table 1. By-products present in the starting materials and resulting from the rearrangement have not been identified. [Table] −Dihydrofuran
-dihydrofuran
【table】

Claims (1)

[Claims] 1 formula [However, R is an ethyl or vinyl group, and R ₂
is a C _1-4 alkyl group, and R ₁ is 3 to 10
an alkyl group having 5 carbon atoms. 2. The fragrance composition according to claim 1, wherein R ₁ is a straight-chain alkyl group. 3. The fragrance composition according to claim 1 or 2, wherein R ₁ is a C _3-8 alkyl group. 4. The fragrance composition according to any one of claims 1 to 3, wherein R ₂ is methyl or ethyl. 5 4-carbethoxy-5-n-pentyl-2-
Vinyl-2,3-dihydrofuran, 4-carbetoxy-5-n-pentyl-2-ethyl-2,3-dihydrofuran, 4-carbethoxy-5-(3-methyl-butyl)
-2-vinyl-2,3-dihydrofuran, 4-carbethoxy-5-(3-methyl-butyl)
-2-ethyl-2,3-dihydrofuran, or (4-carbethoxy-5-(4-methyl-
The fragrance composition according to claim 1, which is 3-pentenyl)-2-vinyl-2,3-dihydrofuran.