JPH11228479A - Production of aldehydes or ketones using arylboron compound catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce aldehydes or ketones useful for synthesizing medicines or chemically synthesizing an organic material, reduce the amount of a catalyst and further reduce a load on an environment by oxidizing allyl alcohol in the presence of a specific polyphosphoric acid catalyst. SOLUTION: Perillyl alcohol represented by formula I, an alcohol represented by formula III (R<1> and R<2> are each independently H, a 1-10C aliphatic hydrocarbon group or the like; R<3> is H or a 1-4C alkyl) or an alcohol represented by formula V (X is H, a halogen or the like; R<4> is H; R<5> is H or a halogen and R<6> and R<7> are each H or R<4> and R<5> together form a benzene ring; R<6> and R<7> are each H or R4 is H; R<5> is H, a halogen or the like; R<6> and R<7> together form a 5-membered ring) is oxidized in the presence of an arylboron compound catalyst represented by the formula Ar3 B(OH)3-n [Ar is C6 F5 ; (n) is 2 or 3] to respectively provide perillaaldehyde represented by formula II, an unsaturated ketone (an α,β-unsaturated ketone) represented by formula IV or an aromatic ketone represented by formula VI.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for oxidizing allyl alcohol, and more particularly to a method for oxidizing allyl alcohol in the presence of a specific borinic acid catalyst to produce an aldehyde compound or a ketone compound.

[0002]

2. Description of the Related Art Oppenauer oxidation (O)
PP) is one of the useful methods for converting secondary alcohols to ketones. In this method, functional groups such as carbon-carbon double bonds, triple bonds, aldehydes, amines, halogens, and sulfur-containing groups are not affected. Therefore,
This OPP method is a very advantageous process. But,
Generally, it is difficult to oxidize a primary alcohol to the corresponding aldehyde by the OPP method. That is,
Oxidation of primary alcohols is mainly caused by side reactions such as aldol reaction following oxidation because the reactants are basic.

On the other hand, a wide variety of organic and inorganic metal reagents have been reported as OPP catalysts. OPP
As a conventional method of oxidizing allyl alcohol to aldehyde or ketone using a method, a process using an excessive amount of activated manganese dioxide has been common. However, the degree of activity of activated manganese dioxide is not always constant depending on the method of producing it, and the state of the reaction often depends on the amount of the oxidizing agent used and the type of the solvent, so it has been difficult to search for experimental conditions. In addition, the amount of active manganese dioxide generally used is 5 to 30 times the weight of the substrate, which is a large excess, which is not suitable for large-scale synthesis, and also has a problem of discharging a large amount of manganese waste.

[0004]

It is very important in organic synthesis to obtain an unsaturated carbonyl compound efficiently by oxidizing allyl alcohol. Moreover, there has been almost no practical oxidation method which can be applied industrially as described above. Therefore, the development of an environmentally friendly catalytic oxidation reaction has been expected for the purpose of providing a large amount and high purity of the unstable unsaturated carbonyl compound. The present invention has been made to meet such a demand.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the present invention

Embedded image Perillyl alcohol represented by
Formula II:

Embedded image (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula III:

Embedded image And obtaining perillaldehyde represented by the formula:

Further, the present invention provides a compound of the following formula IV:

Embedded image (In the formula, R ¹ or R ² is independently a hydrogen or a C ₁ -C ₁₀ branched or straight-chain saturated or unsaturated aliphatic hydrocarbon group which may be optionally substituted with halogen.) Yes,
R ³ is hydrogen or C ₁ -C ₄ alkyl) of the formula II:

Embedded image (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula V:

Embedded image (Wherein R ¹ , R ² , and R ³ have the meanings defined in Formula I, respectively).

Further, the present invention provides the following formula VI:

Embedded image Wherein X is hydrogen, halogen or C ₁ -C ₄ alkyl, R ⁴ is hydrogen, R ⁵ is hydrogen or halogen, R ⁶ and R ⁷ are each hydrogen; or X is hydrogen, halogen or C ₁ -C ₄ alkyl, R ⁴ and R ⁵ are both together form a benzene ring, R ⁶
And R ⁷ are each hydrogen; or X is hydrogen, halogen or C ₁ -C ₄ alkyl, R ⁴ is hydrogen, R ⁵ is hydrogen, halogen or C ₁ -C ₄ alkyl, R ⁶ and R ⁷ together form a 5-membered ring)
The alcohol represented by the following formula II:

Embedded image (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula VII:

Embedded image Wherein an aromatic ketone represented by the formula:

Further, the present invention provides the following formula VIII:

Embedded image The myrtenol represented by the following formula II:

Embedded image (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula IX:

Embedded image Wherein a crosslinked ring aldehyde represented by the formula: is obtained.

Further, the present invention provides the following formula X:

Embedded image (S) -cis-verbenol represented by
Formula II:

Embedded image (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula XI:

Embedded image Wherein a crosslinked ketone represented by the formula:

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies to develop a catalyst having excellent activity which does not have the above-mentioned disadvantages in the above-mentioned Oppenauer oxidation reaction, and as a result, bis (penfluorophenyl) The present inventors have found that bolinic acid is an excellent catalyst in the oxidation reaction, and completed the present invention.

That is, using an organic solvent such as a toluene solvent, a bis (pentafluorophenyl) borinic acid catalyst of 1 to 2 mol%, 6 equivalents of bivalaldehyde (hydrido acceptor), The desired carbonyl compound can be obtained almost quantitatively only by adding magnesium (drying agent) and stirring at room temperature for several hours. The oxidation reaction proceeded smoothly with allyl alcohol regardless of primary or secondary. The present invention is also effective for primary benzyl alcohol and cyclic secondary benzyl alcohol. That is, alcohols (substrates) to which the present invention can be applied include allyl alcohols, benzyl alcohols,
Alcohols containing other functional groups (eg, halogen, ether, etc.) in the molecule and other functional groups (eg, halogen, ether, etc.)
Ether) in the molecule.

On the other hand, since the reactivity of bulky benzyl alcohol and saturated alcohol is significantly reduced, it has been found that the present invention is particularly effective for the selective oxidation of allyl alcohol.

In the process of the present invention, bis (pentafluorophenyl) borinic acid is most preferably used, but tris (pentafluorophenyl) boron (n = 3 in formula II) can also be used as a catalyst.

The aryl boron compound catalyst used in the method of the present invention can be preferably prepared, for example, as follows. A representative catalyst in the present invention, namely bis (pentafluosphenyl) borinic acid (a catalyst represented by the following formula 1b), is obtained by hydrolyzing a known chloroborane using aqueous 2N HCl ((a) Chamber).
s, RD; Chivers, TJ Chem. Soc. 1964, 4782, (b) C
humbers, RD; Chivers, TJChem. Soc. 1965, 393
3). The bis (pentafluorophenyl) borinic acid is a white microcrystalline solid, easy to handle in air, and soluble in many organic solvents. Furthermore, the bis (pentafluorophenyl) borinic acid is a stronger Lewis acid than (pentafluorophenyl) boronic acid, but weaker than tris (pentafluorophenyl) boron.

In the process of the present invention, the alcohol which can be used as a substrate in the presence of the above-mentioned aryl boron compound catalyst is obtained by converting an aromatic organic solvent such as benzene or toluene;
Halogen-based organic solvents such as dichloromethane, or dissolved or suspended in an aliphatic organic solvent such as cyclohexane or octane, for example, can be carried out at 0 to 160 ° C. for a reaction time of 5 minutes to 42 hours. 2 at room temperature
It can be carried out by stirring for ５5 hours. It is very effective to carry out this reaction process in the presence of a large excess of ketones such as benzophenone or aldehydes such as pival aldehyde and benzaldehyde. The reaction product can be purified by a conventional method using chromatography or the like.

The process according to the invention makes it possible to obtain the desired products in very high yields, as is also demonstrated in the examples.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples.

EXAMPLE 1 The following equations 1a, 1b and 1c, 2b and 3
b:

Embedded image (S) -perillyl alcohol using various aryl boron compounds represented by
Was oxidized. Table 1 shows the oxidation reaction conditions and the yield of the produced compound.

[0018]

[Table 1]

That is, in the oxidation reaction, 1-2
Using mol% of catalyst, 6 equivalents of pivalaldehyde (t-BuCHO) were used as hydride acceptor. As shown in Table 1, the diaryl boron compound, particularly the catalyst of 1b, showed the highest activity (Experiment No. 2, Vs No. 4,
5). On the other hand, the catalyst of 1a had no catalytic activity at all.

Interestingly, the catalyst 1c showed the same activity as the catalyst b. This shows that under the reaction conditions, catalyst 1
This is because c gradually decomposes to borinic acid 1b and trifluorobenzene, and finally to boric acid 1a. That is, the true catalytically active species is not the catalyst 1c but the catalyst 1b. Therefore, in order to improve the catalytic activity in this reaction, it is necessary to take measures to prevent the decomposition of borinic acid. Bolinic acid is generally neutral or basic and easily decomposed, and is relatively stable under acidic conditions. It can be inferred that the decomposition of borinic acid in this reaction was caused by nucleophilic addition of generated water, aldehyde or raw material alcohol to boron, and in fact, addition of magnesium sulfate to the reaction system was effective.

Next, the experimental procedure in the embodiment will be described. Experimental procedure: Under an argon atmosphere, bis (pentafluorophenyl) borinic acid 1b (3.6 mg, 0.01 mmol)
l), magnesium sulfate (120 mg, 1.0 mmol
l), (S) -perillyl alcohol
(159 mL, 1.0 mmol) mixed with toluene (2
pivalaldehyde (326 mL, 3. mL).
0 mmol) was added at room temperature. After stirring for 3 hours, the reaction mixture was quenched with saturated aqueous sodium hydrogen carbonate (5 mL) and extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product was purified by silica gel chromatography (developing solvent, pentane: diethyl ether = 7: 1) to obtain the desired perillaldehyde at a chemical yield of 99% (149 mg).

Next, the method of the present invention was applied to various alcohols using bis (pentafluorophenyl) borinic acid which was found as a preferred catalyst in Example 1. Examples are shown in Examples 2 to 8.

Example 2 Under an argon atmosphere, bis (pentafluorophenyl) borinic acid (7.2 mg, 0.02 mmol), magnesium sulfate (120 mg, 1.0 mmol), 2-tridecene-1-ol (198 mg, 1. 0 mmol) in a toluene (2 mL) suspension mixed with pivalaldehyde (4 mmol).
36 μL, 4.0 mmol) were added at room temperature. After stirring for 27 hours, a saturated aqueous sodium bicarbonate solution (5 mL) was added to the reaction mixture to stop the reaction, and the mixture was extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product was purified by silica gel chromatography (developing solvent, pentane: diethyl ether = 7: 1) to obtain 2-tridecenal in a chemical yield of 85% (167 mg) (see Table 2, Experiment No. 1). .

Example 3 Toluene mixed with bis (pentafluorophenyl) borinic acid (3.6 mg, 0.01 mmol), magnesium sulfate (120 mg, 1.0 mmol) and geraniol (173 μL, 1.0 mmol) under an argon atmosphere. (2
pivalaldehyde (327 μL, 3. mL) in the suspension.
0 mmol) was added at room temperature. After stirring for 3 hours, the reaction mixture was quenched with saturated aqueous sodium hydrogen carbonate (5 mL) and extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product was purified by silica gel chromatography (developing solvent, pentane: diethyl ether = 7: 1) to give the desired geranyl aldehyde in a 95% chemical yield (145%).
mg), E / Z = 99: 1 (see Table 2, Experiment No. 2).

Example 4 Bis (pentafluorophenyl) borinic acid (3.6 mg, 0.01 mmol), magnesium sulfate (120 mg, 1.0 mmol), nerol (1
76 μL, 1.0 mmol) mixed with toluene (2 m
L) Pivalaldehyde (327 μL, 3.0) was added to the suspension.
mmol) at room temperature. After stirring for 3 hours, the reaction mixture was quenched with saturated aqueous sodium hydrogen carbonate (5 mL) and extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product was purified by silica gel chromatography (developing solvent, pentane: diethyl ether = 7: 1), and the target geranyl aldehyde was converted to a 98% chemical yield (150 m
g), E / Z = 72: 28 (see Table 2, Experiment No. 3).

Example 5 Bis (pentafluorophenyl) borinic acid (3.6 mg, 0.01 mmol), magnesium sulfate (120 mg, 1.0 mmol), (1R)-
(−)-Myrtenol (152 mg, 1.
Pivalaldehyde (327 μL, 3.0 mmol) was added to a suspension of toluene (2 mL) mixed with 0 mmol) at room temperature. After stirring for 3 hours, the reaction mixture was added to a saturated aqueous sodium hydrogen carbonate solution (5%).
mL) to stop the reaction, and the mixture was extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product was purified by silica gel chromatography (developing solvent, pentane: diethyl ether = 10: 1) to obtain the desired myrtenal in a chemical yield (150 mg) of> 99% (Table 2, experiment). No. 4).

Example 6 Under an argon atmosphere, bis (pentafluorophenyl) borinic acid (3.6 mg, 0.01 mmol), magnesium sulfate (120 mg, 1.0 mmol), (S) -cis-verbenol (verbenol, Synonyms (1S-cis) -4,6
6-trimethylbicyclo [3.3.1] hept-3-en-2
-Ol) (152 mg, 1.0 mmol) in a toluene (2 mL) suspension mixed with pivalaldehyde (327 μl).
L, 3.0 mmol) at room temperature. After stirring for 2 hours,
Saturated aqueous sodium hydrogen carbonate (5 mL) was added to the reaction mixture to stop the reaction,
Extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product was purified by silica gel chromatography (developing solvent, pentane: diethyl ether = 2: 1), and the desired (1S)-(−)-verbenone (verbeno) was obtained.
ne, also known as (1S-cis) -4,6,6-trimethylbicyclo
[3.3.1] Hept-en-2-one) was obtained in a chemical yield (150 mg) of> 99% (see Table 2, Experiment No. 5).

Example 7 Under an argon atmosphere, bis (pentafluorophenyl) borinic acid (7.2 mg, 0.02 mmol), magnesium sulfate (120 mg, 1.0 mmol) and 1-naphthalenemethanol (158 mg, 1.0 mmol) were added. Pivalaldehyde (43 mL) was added to the mixed suspension of toluene (2 mL).
6 μL, 4.0 mmol) at room temperature. After stirring for 42 hours, the reaction mixture was quenched with saturated aqueous sodium hydrogen carbonate (5 mL) and extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product is subjected to silica gel chromatography (developing solvent, pentane: diethyl ether = 12: 1)
To give the desired 1-naphthaleneacetaldehyde in 85% chemical yield (133 mg) (Table 2,
Experiment No. 6).

Example 8 Under an argon atmosphere, bis (pentafluorophenyl) borinic acid (7.2 mg, 0.02 mmol), magnesium sulfate (240 mg, 2.0 mmol), and 1-indanol (134 mg, 1.0 mmol) were mixed. To a suspension of toluene (2 mL) was added pivalaldehyde (436 μL,
4.0 mmol) was added at room temperature. After stirring for 5 hours, a saturated aqueous sodium hydrogen carbonate solution (5 mL) was added to the reaction mixture to stop the reaction, and the mixture was extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure.
The crude product is subjected to silica gel chromatography (developing solvent,
Purified by pentane: diethyl ether = 3: 1),
The target 1-indanone was converted to a 90% chemical yield (119).
mg) (see Table 2, Experiment No. 7).

Next, when the process of the present invention is applied, the reactivity may decrease depending on the substrate. For example, when the substrate is bulky benzyl alcohol or saturated alcohol. Hereinafter, those examples are shown as comparative examples.

Comparative Example 1 Under an argon atmosphere, bis (pentafluorophenyl) borinic acid (7.2 mg, 0.02 mmol), magnesium sulfate (240 mg, 2.0 mmol), 1-phenyl-1-propanol (136 mg, 1. Pivalaldehyde (327 μL, 3.0 mmol) was added to a suspension of toluene (2 mL) mixed with 0 mmol) at room temperature. After stirring for 5 hours, a saturated aqueous sodium hydrogen carbonate solution (5 mL) was added to the reaction mixture to stop the reaction, and the mixture was extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product was purified by silica gel chromatography (developing solvent, pentane: diethyl ether = 12:
Purification according to 1) to obtain the desired 1-phenyl-1-propanone in a chemical yield of 20% (27 mg) (Table 2,
Experiment No. 8).

Comparative Example 2 Toluene mixed with bis (pentafluorophenyl) borinic acid (7.2 mg, 0.02 mmol), magnesium sulfate (120 mg, 1.0 mmol) and tridecanol (200 mg, 1.0 mmol) under an argon atmosphere. (2 mL) pivalaldehyde (436 μL,
4.0 mmol) was added at room temperature. After stirring for 6 hours, the reaction mixture was added with saturated aqueous sodium hydrogen carbonate (5 mL) to stop the reaction, and extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure.
The crude product is subjected to silica gel chromatography (developing solvent,
Although purified by pentane: diethyl ether = 7: 1), tridecanal containing impurities which cannot be separated is <26.
% (52 mg) (see Table 2, Experiment No. 9).

Comparative Example 3 Under an argon atmosphere, bis (pentafluorophenyl) borinic acid (7.2 mg, 0.02 mmol), magnesium sulfate (120 mg, 1.0 mmol), 4-t-butylcyclohexynol (156 mg, 1. Pivalaldehyde (327 μL, 3.0 mmol) was added to a suspension of toluene (2 mL) mixed with 0 mmol) at room temperature. After stirring for 6 hours, the reaction mixture was added with saturated aqueous sodium hydrogen carbonate (5 mL) to stop the reaction, and extracted twice with diethyl ether. The obtained organic phase was dried over magnesium sulfate, filtered, and then concentrated under reduced pressure. The crude product is subjected to silica gel chromatography (developing solvent, pentane: diethyl ether = 7: 1)
To obtain the desired 4-t-butylcyclohexanone in a chemical yield of 49% (76 mg) (see Table 2, Experiment No. 10).

[0034]

[Table 2]

APPLICATION EXAMPLES As described above, the method of the present invention is very effective for the selective oxidation of allyl alcohol. For example, if the carveol oxidation reaction with a scene-to-anti ratio of 42:58 is carried out using 1 mol% of catalyst 1b, the syn isomer is preferentially oxidized to give carvone in a yield of 48% and recovered. Carveol was 98% anti-isomer (formula
XII). That is, even with the same allyl alcohol, a hydroxyl group having less steric hindrance is easily oxidized selectively. In the reaction of the formula XII, the syn isomer has less steric hindrance and the reaction proceeds selectively.

When the oxidation reaction of a one-to-one mixture of geraniol and β-citronellol is similarly performed, geraniol, which is an allyl alcohol, is preferentially oxidized, and the ratio of geranial to citronellal obtained is 93: 7. (Formula XIII).

[0037]

Embedded image

[0038]

Embedded image

[0039]

As described above, the present invention is designed to oxidize alcohols to which Oppenauer oxidation is applied in the presence of a specific catalyst, that is, an arylboron compound. The oxidation reaction proceeds smoothly with any allyl alcohol, whether primary or secondary, and has the effect of obtaining a reaction product, aldehyde or ketone, in high yield. Further, the method of the present invention can be effectively applied to primary benzyl alcohol and cyclic secondary benzyl alcohol. On the other hand, since the reactivity of bulky benzyl alcohol and saturated alcohol is significantly reduced, the method of the present invention is particularly effective for the selective oxidation of allyl alcohol. Therefore, the method of the present invention has an effect that can be widely applied to pharmaceutical synthesis and chemical synthesis of organic materials.

Furthermore, the amount of manganese dioxide conventionally used as a catalyst is in a large excess with respect to the substrate, and the treatment of manganese waste is an environmental problem.
On the other hand, in the method of the present invention, by using a specific arylboron compound as a catalyst, the amount used can be extremely small with respect to the substrate. Therefore, there is an effect that an environmentally friendly catalytic oxidation reaction can be performed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C07C 47/23 C07C 47/23 47/45 47/45 49/627 49/627 49/67 49/67 // C07B 61/00 300 C07B 61/00 300

Claims (5)

[Claims] 1. The following formula I: Perillyl alcohol represented by
The following formula II: Wherein Ar represents C ₆ F ₅ and n is 2 or 3 in the presence of an aryl boron compound catalyst represented by the following formula III: A method for producing perillaaldehyde, characterized by obtaining an aldehyde represented by the formula: 2. The following formula IV: (In the formula, R ¹ or R ² is independently a hydrogen or a C ₁ -C ₁₀ branched or straight-chain saturated or unsaturated aliphatic hydrocarbon group which may be optionally substituted with halogen.) Yes,
R ³ is hydrogen or C ₁ -C ₄ alkyl) with an alcohol of the following formula II: (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula V: (Wherein R ¹ , R ² , and R ³ have the meanings defined in Formula I), wherein α, β-unsaturated ketone is obtained. 3. The following formula VI: An alcohol represented by the following formula II: wherein X is hydrogen,
R ⁴ is hydrogen, R ⁵ is hydrogen or halogen, and R ⁶ and R ⁷ are halogen or C ₁ -C ₄ alkyl.
Is each hydrogen; or X is hydrogen, halogen or C ₁ -C ₄ alkyl, R ⁴ and R ⁵ together form a benzene ring, and R ⁶ and R ⁷ are each hydrogen Or X is hydrogen, halogen or C ₁ -C
Is ₄ alkyl, R ⁴ is hydrogen, R ⁵ is hydrogen, halogen or C ₁ -C ₄ alkyl, represented by R ⁶ and R ⁷ are both together form a 5-membered ring) The alcohol is converted to the following formula II: (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula VII: (Wherein R ⁴ , R ⁵ , R ⁶ and R ⁷ have the meanings defined by the formula IV). 4. The following formula VIII: The myrtenol represented by the following formula II is represented by the following formula II: (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula IX: A method for producing a crosslinked ring aldehyde compound, characterized by obtaining an aldehyde represented by the formula: 5. The following formula X: (S) -cis-verbenol represented by
The following formula II: (Wherein, Ar represents C ₆ F ₅ and n is 2 or 3)
Oxidation in the presence of an aryl boron compound catalyst represented by the following formula XI: A method for producing a bridged ring ketone compound, characterized by obtaining a ketone represented by the formula: