JPS58146530A - Preparation of 9-ketodihydro-alpha-damascone - Google Patents

Abstract

PURPOSE:To prepare the titled compound useful as an intermediate of an aromatic substance, damascone, etc., in high efficiency, with a single step reaction, by using a cyclogeranic acid derivative as a starting material, and reacting with a chain ketone in the presence of a carbanionizing agent. CONSTITUTION:The cycloaliphatic diketone of formula III (R5 and R6 are 1-2C alkyl; m is 0-2; n is 1-3) (e.g. 9-ketodihydro-alpha-damascone) is prepared by carbanionizing a chain ketone of formulaI(R' and R'' are R5 and R6; a and b are integer of 1-3) (e.g. acetone) with a carbanionizing agent such as sodium amide, and reacting with a cyclogeranic acid derivative of formula II (R1-R4 are H or <=3C alkyl; X is halogen or alkoxy; one of the dotted lines is double bond), e.g. alpha-cyclogeranic acid chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing an alicyclic diketone represented by the general formula (III), and more specifically, for efficiently producing the alicyclic diketone in one step from a cyclogeranic acid derivative. Regarding the method.

Alicyclic diketones represented by the above general formula [111), such as 9-ketodihydro-α-damaskot, 9-ketodihydro-β-damascone, 9-ketodihydro-β-damascone, etc., are themselves useful as aromatic substances. De),
In addition, since damascone can be easily obtained by reducing and dehydrating such alicyclic diketones, it is a useful substance as an intermediate for damascone (for example, JP-A-49-7
(Refer to No. 250) 0 Conventionally, methods for synthesizing such alicyclic diketones include
The following method using Yono/ as a starting material is known (
(see the above-mentioned publication), such a method requires a long reaction process and cannot necessarily be said to be efficient.

Therefore, the present inventors conducted intensive studies to efficiently synthesize the desired alicyclic diketo in a shorter process, and found that the desired object could be obtained in one step by using a cyclogeranic acid derivative as a starting material. Thus, the present invention is characterized in that a linear ketone represented by the general formula CI) is reacted with a cyclogeranic acid derivative represented by the general formula (It) in the presence of an agent for carbanionizing the ketone. A novel method for producing an alicyclic diketone represented by general formula (II) is provided.

(R')-C(--c-c(a)b-(R'')...
・・・・・・ [Engineering] S-&
M-b (in the formula, R' and R'' are alkyl groups having 1 to 2 carbon atoms, and a and b represent integers of 1 to 5) 1 (in the formula, R1, R,, R, and R4ti Hydrogen or an alkyl group having 5 or less carbon atoms, X represents a halogen or an alkoxy group, and one of the positions indicated by the dotted line represents a double bond) 1 (wherein, R,, R,, R,, R2 and the meanings of the dotted line parts are the same as above, and R1 and Ro are the above R' or R''
In the present invention, a chain ketone represented by the general formula [■] is used as the first component of the starting material. is used. Specific examples of such ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone, etc. Acetone also lasts a long time.

On the other hand, the cyclogeranic acid derivative used as the second component is represented by the general formula [I[] when α-1β
- or because of r-cyclogeranic acid -
−飄 −−柟＋ −1−１ −１
Specific examples of acid halides include acid chloride, acid bromide, etc., and specific examples of esters include methyl ester, ethyl ester, etc. Among these, acid halides and <K acid chloride are prized from the standpoint of reactivity and economy, and α-cyclogranic acid chloride is particularly prized.

The α-1β- and γ-cyclogranic acid derivatives can be easily synthesized according to known methods (see, for example, Japanese Patent Publication No. 5528/1983).

The reaction in the present invention is carried out by previously converting the chain ketone into a total carbanion and then contacting it with a cyclogeranic acid derivative. For example, taking acetone as a chain keto/, the following anti-OH.

The carbanionizing agent used in the reaction may be any agent that can efficiently form a carbanion of a chain ketone, and specific examples thereof include lithium, sodium, potassium, etc. Examples include alkali metals such as alkali metals, amides of these alkali metals, hydrides, alkylated products, alkoxides, etc.Among them, alkali metal amides, especially sodium amide, are preferred from the viewpoint of reactivity and economy.

In the present invention, first, a chain ketone and a carbanionizing agent are mixed at 180 to 50C in the presence or absence of a diluent.
A linear keto/carbanion is formed by contacting for minutes to 2 hours. At this time, the amount of the carbanionizing agent to be used is appropriately selected within a range that can generate the carbanion necessary for the reaction with the cyclogranic acid derivative.

The diluent used in the reaction may be any diluent as long as it is inert to the reaction, specific examples of which include diethyl ether,
Examples include polar solvents such as tetrahydrofuran, and hydrocarbon solvents such as hexane, heptane, benzene, toluene, and cyclohexane. Such a diluent is usually used in a proportion of 10 times or less by weight relative to the ketone.

After forming the carbanion, the desired alicyclic diketo/ is synthesized by reacting with a cyclogeranic acid derivative. Such a reaction is usually carried out at a temperature of -80 to 50C, preferably -50 to 50C for 1 minute to 5 hours. Also, the amount of cyclogeranic acid derivative used is per mole of pre-formed carbaeoff! OA constant 0.1
~0.7 mol, preferably 0.2-0.5 mol,
If the amount used is excessively large, by-products will increase, which is undesirable.

After the reaction is completed, the target product is separated from the reaction solution according to a conventional method to obtain a highly pure alicyclic diketo.In addition, unreacted cyclogranic acid derivatives or their hydrolyzed derivatives may be present in the reaction solution. There is also generated cyclogeranic acid, which can be recovered separately and reused as a raw material.Thus, according to the present invention, the desired alicyclic diketone can be efficiently produced in one step using inexpensive raw materials. Obtainable.

The present invention will be described in more detail with reference to Examples below. In the Examples, parts and weights are based on weight unless otherwise specified. Example 1 Sodium amide 0. 6P (15mm
After refluxing f) and 611 tl of dry ether for 30 minutes, 5wt1 of dry ether was added, and acetone Q, 5 ml of dry ether was added at room temperature. (9
A mixed solution of Otori so/ ) and dry ether 2.2114 was added dropwise, stirred for 20 minutes, cooled to mouth C, and α-cyclogeranate dichloride 05 f (2.7 mmo
/) and dry ether 15 III was quickly added and stirred for 5 minutes at OC and 15 minutes at room temperature. After that,
Separated on a silica gel column (solvent benzene), 0.225 L of 9-ketodihydro-α-damascone (1.2 mm
o/)f obtained. The yield was 40% based on α-cyclogeranate dichloride.

In addition to the target product, 0.20 P (12 mmo/) of α-cyclogranic acid was obtained by hydrolysis of unreacted raw materials.

Example 2 The temperature at the time of dropping acetone was changed to t--100, and Chikarashimatsu α
-Reaction conditions for cyclogeranic acid chloride t--10
The reaction was carried out in the same manner as in Example 1 except that the reaction was carried out for 2 hours after the dropwise addition at C and then for 50 minutes at room temperature. The yield of 9-ketodihydro-α-damascone was 52.
It was 1t'4.

Example 6 Acet/α5? , dry ether 121111 and sodium metal α3y- were stirred with OC for 15 minutes, then α-
Add a mixture of cyclogeranic acid chloride n,sy and dry ether 2- for 30 min at OC and then for 60 min at room temperature.
The mixture was stirred for a minute. Thereafter, methanol was added and column separation was performed in the same manner as in Example 1 to obtain 9-ketodihydro α-damascone α08? Obtained 0 Patent applicant Takao Kata Kiri

Claims (1)

[Scope of Claims] t A general method characterized in that a chain ketone represented by the general formula CI) is reacted with a cyclogeranic acid derivative represented by the general formula [II] in the presence of an agent for carbanionizing the ketone. A method for producing an alicyclic diketone represented by the formula (fit). (R'), τ, C! (H)a-00(1'Ob (
R'-5... CI) (In the formula, R' and R' are alkyl groups having 1 to 2 carbon atoms, and a and b represent integers of 1 to 3) bar (In the formula, R R R R1 and R4 Fi hydrogen or carbon number 3
In the following alkyl group, X represents a halogen 4-alkoxy group, and one of the positions indicated by a dotted line represents a double bond) Same as above, R1 and Ro are R' or R', Otori is an integer from 0 to 2), nij is an integer from 1 to 3)