Method for producing [6,6] methanofullerene derivatives

Abstract

To provide an efficient production method of a methanofullerene derivative suited for mass production, and to provide a sulfone compound suitably used in the production method.SOLUTION: A production method of a [6,6]methanofullerene derivative is characterized as including a step to make a sulfone compound represented by formula (I) and fullerene react with each other in a solvent and in the presence of a base. [In formula, R1 indicates a C1-30 alkyl group which may have a substituent or the like, R2 indicates a C6-30 aryl group which may have a substituent or the like, R3 indicates H or -X-C(=O)O-R4 (in formula, X indicates a single bond or a C1-10 alkanediyl group, and R4 indicates a C1-30 alkyl group which may have a substituent or the like).]SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an efficient method for producing a [6,6] methanofullerene derivative that is suitable for mass production, and to a sulfone compound that can be suitably used in said method. [Background technology]

[0002] Photovoltaic power generation, which converts light energy such as sunlight into electrical energy, is an extremely clean power generation method that does not emit CO2 or other exhaust gases, and is expected to reduce greenhouse gases and solve the global warming problem. Among these, organic thin-film solar cells are considered promising next-generation solar cells because they can be produced in large areas, easily and inexpensively, are lightweight, and are highly flexible. Toward practical use, it is important to establish manufacturing methods suitable for the industrialization of various materials.

[0003] In 1992, it was shown that fullerene C60 has properties as an electron-accepting material for organic thin-film solar cells (Non-Patent Document 1, Patent Document 1). Furthermore, in order to increase the compatibility of fullerene with hole-transporting materials, methanofullerene PC61BM ([6,6]-phenyl C61 butyric acid methyl ester) was synthesized by crosslinking a phenyl group and a butyric acid ester group with methylene (Non-Patent Document 2), and the photoelectric conversion efficiency was significantly improved compared to C60.

[0004] On the other hand, as a fullerene other than C60, C70 is highly available and has absorption in the longer wavelength region compared to C60, so it can absorb energy on the longer wavelength side, and its use as an electronic material is being actively promoted. In Patent Document 2 and Non-Patent Document 3, it was confirmed that by using methanofullerene PC71BM ([6,6]-phenyl C71 butyric acid methyl ester) synthesized using C70 in a photoelectric conversion layer, the photoelectric conversion efficiency was improved by 50% or more compared to PC61BM. Unlike fullerene C60, fullerene C70 has an elliptical hollow structure, and therefore has two double bonds, α-bonds and β-bonds, which have different chemical reactivity and steric hindrance. This PC71BM was used as a mixture of two types of positional isomers containing about 85% of the α-form obtained by a conventionally known manufacturing method, but in Patent Document 3, a precise isomer separation operation was added to increase the proportion of one positional isomer to 95% or more, and an even higher photoelectric conversion efficiency was demonstrated.

[0005] Currently, the above-mentioned methanofullerene derivatives are used as standard materials in the development of organic thin-film solar cells, and therefore there is a demand for the establishment of a manufacturing method suitable for industrialization.

[0006] However, the conventionally known manufacturing method of methanofullerene derivatives including PC61BM requires high temperature and long reaction time, and since the process goes through the fullerene [5,6] adduct fulleroid, it is necessary to isomerize the [6,6] adduct to metallofullerene under ultra-high temperature conditions. Specifically, C60 is added to methyl 4-benzoylbutyric acid p-tosylhydrazone as a precursor of the addition raw material, and the mixture is heated and stirred at 70°C for a long period of 22 hours, and then the [5,6] adduct fulleroid obtained as an intermediate is subjected to thermal isomerization at a high temperature of 180°C for 7 hours to obtain the [6,6] adduct PC61BM (Non-Patent Document 2).

[0007] Furthermore, the production of PC71BM is also accompanied by the same problems as the production of PC61BM, since it is synthesized in the same manner as PC61BM (Non-Patent Document 3). In addition, in the production of PC71BM, a mixture of two extremely difficult positional isomers, the main component being the α form, is obtained. For this reason, Patent Document 3 employs a labor-intensive isolation method using high performance liquid chromatography (HPLC) to increase the proportion of positional isomers, which poses a problem in terms of production costs.

[0008] The present inventors have developed a reaction between a metastable sulfur ylide prepared from a sulfonium salt and C60. In this method, [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) is obtained without forming the [5,6] isomer. In the reaction with fullerene C70, it was shown that the production rate of α-PC71BM can be improved to 98% by using a sulfur ylide prepared from a diisopropyl (5-methoxy-5-oxo-1-phenylpentyl) sulfonium salt (Patent Document 4, Non-Patent Documents 4-5). On the other hand, in Patent Document 5 and Patent Document 6, α-PC71BM is synthesized at 98% by using a sulfur ylide prepared from the same diisopropyl (5-methoxy-5-oxo-1-phenylpentyl) sulfonium salt. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent No. 5,331,183 [Patent Document 2] Special table number 2006-518110 [Patent Document 3] Patent Publication No. 2009-76683 [Patent Document 4] Patent Publication No. 2014-034519 [Patent Document 5] U.S. Patent No. 9,527,797 [Patent Document 6] Patent Publication No. 2017-197518 [Non-patent literature]

[0010] [Non-Patent Document 1] NSSariciftci,et al.,Science,1992,258,1474 [Non-Patent Document 2] JCHummelen,et al.,J.Org.Chem.,1995,60,532 [Non-Patent Document 3] MMWienk,et al.,Angew.Chem,Int.Ed.,2003,42,3371 [Non-Patent Document 4] T.Ito,et al.,Synlett,2013,24,1988 [Non-Patent Document 5] T. Ito,et al.,Synlett,2017,28,1457 Summary of the Invention [Problem to be solved by the invention]

[0011] As mentioned above, methanofullerene derivatives have attracted attention as materials for organic thin-film solar cells. However, conventional methods for producing methanofullerene derivatives require a thermal transfer reaction from [5,6] fulleroid to [6,6] metallofullerene, which is inefficient, and the raw material compounds are not stable, making them unsuitable for industrial mass production. Therefore, an object of the present invention is to provide an efficient method for producing a methanofullerene derivative suitable for mass production, and a sulfone compound that can be suitably used in said method. [Means for solving the problem]

[0012] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the desired methanofullerene derivative can be efficiently obtained by reacting a stable sulfone compound with a fullerene in the presence of a base, thereby completing the present invention. The present invention will now be described.

[0013] [1] A method for producing a [6,6] methanofullerene derivative, comprising: A method comprising the step of reacting a sulfone compound represented by the following formula (I) with a fullerene in the presence of a base in a solvent: [ka] [In the formula, R 1 C which may have a substituent α 1-30 C which may have an alkyl group or a substituent α 2-30 Alkenyl group, C optionally having a substituent α 2-30 Alkynyl group, C optionally having a substituent β 6-30 represents an aryl group or an aromatic heterocyclic group which may have a substituent β, R 2 C which may have a substituent β 6-30 represents an aryl group or an aromatic heterocyclic group which may have a substituent β, R 3 is H, or -XC(=O)OR 4 (wherein X is a single bond or C 1-10 R represents an alkanediyl group. 4 C which may have a substituent α 1-30 C which may have an alkyl group or a substituent α 2-30 Alkenyl group, C optionally having a substituent α 2-30 Alkynyl group, C optionally having a substituent β 6-30 represents an aryl group, an aromatic heterocyclic group which may have a substituent β, or a polyalkylene glycol group; The substituent α is C 1-6 Alkoxy group, C 6-12 Aryl group, C 1-7 represents one or more substituents selected from the group consisting of an alkanoyl group, an amino group, a halogeno group, a hydroxyl group, a nitro group, and a cyano group, The substituent β is C 1-6 Alkyl group, C 1-6 Alkoxy group, C 6-12 Aryl group, C 1-7represents one or more substituents selected from the group consisting of an alkanoyl group, an amino group, a halogeno group, a hydroxyl group, a nitro group, and a cyano group.] [2] The method according to [1] above, wherein the fullerene is a C60 fullerene or a C70 fullerene. [3] The method according to [1] or [2] above, wherein the fullerene is a C70 fullerene, and the proportion of α-isomers in the [6,6] methanofullerene derivative produced by the reaction is greater than 99%. [4] The method according to any one of the above [1] to [3], wherein the solvent is a mixed solvent of an aromatic hydrocarbon solvent and an aprotic polar solvent. [5] The method according to the above [4], wherein the aromatic hydrocarbon solvent is dichlorobenzene. [6] The method according to [4] or [5] above, wherein the aprotic polar solvent is dimethylsulfoxide and / or dimethylformamide. [7] R 2 The method according to any one of the above [1] to [6], wherein is a phenyl group which may have a substituent β. [8] R 4 The method according to any one of the above [1] to [7], wherein [9] A sulfone compound represented by the following formula (II): [ka] [In the formula, R 1 is a C having a substituent γ 1-30 Alkyl group, C with γ substituent 2-30 Alkenyl group, C with γ substituent 2-30 Alkynyl group, C optionally having a substituent γ 6-30 represents an aryl group or an aromatic heterocyclic group which may have a substituent γ, R 2 C which may have a substituent β 6-30 represents an aryl group or an aromatic heterocyclic group which may have a substituent γ, R 4 C which may have a substituent α 1-30C which may have an alkyl group or a substituent α 2-30 Alkenyl group, C optionally having a substituent α 2-30 Alkynyl group, C optionally having a substituent β 6-30 represents an aryl group, an aromatic heterocyclic group which may have a substituent β, or a polyalkylene glycol group, n is an integer of 3 or more and 5 or less, The substituent α is C 1-6 Alkoxy group, C 6-12 Aryl group, C 1-7 represents one or more substituents selected from the group consisting of an alkanoyl group, an amino group, a halogeno group, a hydroxyl group, a nitro group, and a cyano group, The substituent β is C 1-6 Alkyl group, C 1-6 Alkoxy group, C 6-12 Aryl group, C 1-7 represents one or more substituents selected from the group consisting of an alkanoyl group, an amino group, a halogeno group, a hydroxyl group, a nitro group, and a cyano group, The substituent γ represents one or more substituents selected from the group consisting of a halogeno group, a nitro group, and a cyano group.]

[0014] In this disclosure, 6-30 The term "aryl group" refers to a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms. Examples of the aryl group include phenyl, naphthyl, indenyl, biphenyl, anthracenyl, pyrenyl, naphthacenyl, pentacenyl, hexacenyl, and heptacenyl. 6-20 Aryl groups are preferred, C 6-12 Aryl groups are more preferred, with phenyl being even more preferred.

[0015] The term "aromatic heterocyclic group" refers to a 5-membered ring aromatic heterocyclic group, a 6-membered ring aromatic heterocyclic group, or a condensed ring aromatic heterocyclic group having at least one heteroatom such as a nitrogen atom, an oxygen atom, or a sulfur atom. Examples of the heterocyclic group include 5-membered ring heterocyclic groups such as pyrrolyl, imidazolyl, pyrazolyl, thienyl, furyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, and thiadiazole; 6-membered ring heterocyclic groups such as pyridinyl, pyrazinyl, pyrimidinyl, and pyridazinyl; and condensed ring aromatic heterocyclic groups such as indolyl, isoindolyl, quinolinyl, isoquinolinyl, benzofuranyl, isobenzofuranyl, and chromenyl.

[0016] A "single bond" refers to a covalent bond joining two adjacent carbon atoms.

[0017] "C 1-10 The term "alkanediyl group" refers to a linear or branched divalent saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms. Examples of the alkyl group include methylene, ethylene, methylmethylene, n-propylene, methylethylene, n-butylene, methylpropylene, dimethylethylene, n-pentylene, n-hexylene, n-octalene, and n-decanediyl. 1-8 Alkanediyl group or C 1-6 Alkanediyl groups are preferred, C 2-4 Alkanediyl group or -(CH2) 2-4 The - group is more preferred, with n-propylene (n-propanediyl) being even more preferred.

[0018] "C 1-30 The term "alkyl group" refers to a linear or branched monovalent saturated aliphatic hydrocarbon group having 1 to 30 carbon atoms. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, n-decanyl, n-dodecanyl, n-tetradecanyl, n-hexadecanyl, n-octadecanyl, n-icosanyl, n-hexyl, and n-triacontanyl. 1-20 Alkyl group or C 1-10 Alkyl groups are preferred, C 1-8 Alkyl group or C1-6 Alkyl groups are more preferred, C 1-4 Even more preferred is an alkyl group or methyl.

[0019] "C 2-30 The term "alkenyl group" refers to a linear or branched monovalent unsaturated aliphatic hydrocarbon group having 2 to 30 carbon atoms and at least one carbon-carbon double bond. Examples of the alkenyl group include ethenyl (vinyl), 1-propenyl, 2-propenyl (allyl), isopropenyl, 2-butenyl, 3-butenyl, isobutenyl, pentenyl, hexenyl, decenyl, icosenyl, and triacontenyl. 2-20 Alkenyl group or C 2-10 Alkenyl groups are preferred, C 2-8 Alkenyl group or C 2-6 Alkenyl groups are more preferred, C 2-4 Even more preferred is an alkenyl group or ethenyl (vinyl).

[0020] "C 2-30 The term "alkynyl group" refers to a linear or branched monovalent unsaturated aliphatic hydrocarbon group having 2 to 30 carbon atoms and at least one carbon-carbon triple bond. Examples of the alkynyl group include ethynyl, 1-propynyl, 2-propynyl, 2-butynyl, 3-butynyl, pentynyl, hexynyl, decynyl, icosynyl, and triacontinyl. 2-20 Alkynyl group or C 2-10 Alkynyl groups are preferred, C 2-8 Alkynyl group or C 2-6 Alkynyl groups are more preferred, C 2-4 Alkynyl groups are even more preferred.

[0021] The "polyalkylene glycol group" is a group represented by the formula -(CR 11 R 12 -CR 13 R 14 -O) m -H(wherein, R 11 ~R 14 are independently H or C 1-4In the above formula, R represents an alkyl group, and m represents an integer of 1 to 10. 11 ~R 14 As H or C 1-2 An alkyl group is preferred, H or methyl is more preferred, and m is preferably 8 or less, more preferably 5 or less, and even more preferably 3 or less.

[0022] "C 1-6 The term "alkoxy group" refers to a straight-chain or branched-chain aliphatic hydrocarbon oxy group having 1 to 6 carbon atoms. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, t-butoxy, n-pentoxy, and n-hexoxy. 1-4 Alkoxy groups are preferred, C 1-2 Alkoxy groups are more preferred, with methoxy being even more preferred.

[0023] "C 1-7 The term "alkanoyl group" refers to the remaining atomic group obtained by removing OH from an aliphatic carboxylic acid having 1 to 7 carbon atoms. Examples of the alkanoyl group include formyl, acetyl, ethylcarbonyl, n-propylcarbonyl, isopropylcarbonyl, n-butylcarbonyl, isobutylcarbonyl, t-butylcarbonyl, n-pentylcarbonyl, and n-hexylcarbonyl. 1-4 Alkanoyl groups are preferred, C 1-2 Alkanoyl groups are more preferred, with acetyl being even more preferred.

[0024] "Amino group" includes unsubstituted amino groups (-NH2) and one C 1-6 Alkyl-substituted mono(C 1-6 alkyl)amino group and two C 1-6 Alkyl-substituted di(C 1-6 alkyl)amino groups. 1-6 In the alkyl)amino group, two C 1-6The alkyl groups may be the same or different. Examples of such amino groups include mono(C)amino groups such as methylamino, ethylamino, n-propylamino, isopropylamino, n-butylamino, isobutylamino, t-butylamino, n-pentylamino, and n-hexylamino. 1-6 alkyl)amino; di(C)amino such as dimethylamino, diethylamino, di(n-propyl)amino, diisopropylamino, di(n-butyl)amino, diisobutylamino, di(n-pentyl)amino, di(n-hexyl)amino, ethylmethylamino, methyl(n-propyl)amino, n-butylmethylamino, ethyl(n-propyl)amino, and n-butylethylamino; 1-6 Preferably, the amino group is an unsubstituted amino group.

[0025] The term "halogeno group" includes one or more halogeno groups selected from the group consisting of fluoro, chloro, bromo, and iodo.

[0026] The substituent α is a substituent on an aliphatic hydrocarbon group, the substituent β is a substituent on an aromatic group, and the substituent γ is an electron-withdrawing substituent. The number of the substituents α, the substituent β, and the substituent γ is not particularly limited as long as they are substitutable, but can be, for example, 1 or more and 5 or less, preferably 3 or less or 2 or less, and more preferably 1. In addition, when the number of the substituents is 2 or more, the substituents may be the same or different from each other. As the substituent γ, a halogeno group is preferable, and a fluoro group is more preferable.

[0027] The sulfone compound represented by formula (I) is -SO2-R 1 The group is a leaving group. Examples of the group include a methanesulfonyl group, a trifluoromethanesulfonyl group, a benzenesulfonyl group, a p-toluenesulfonyl group, and an o-nitrobenzenesulfonyl group, and the trifluoromethanesulfonyl group is preferable. Effect of the Invention

[0028] According to the method of the present invention, a [5,6] fulleroid is first obtained as an intermediate, and the target [6,6] methanofullerene is directly obtained without the need for a thermal transfer reaction from [5,6] fulleroid to [6,6] methanofullerene, which is highly efficient. In addition, a specific sulfone compound, which is one of the raw material compounds of the method of the present invention, is more stable than an unstable sulfur ylide compound. Therefore, the present invention is extremely useful industrially as a technique capable of efficiently producing methanofullerene derivatives useful as organic thin-film solar cell materials and the like. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 shows the 1H NMR chart of [6,6]PC71BM produced in Example 2 and an enlarged portion of the chart. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The method for producing a [6,6]methanofullerene derivative according to the present invention comprises reacting a sulfone compound represented by formula (I) with a fullerene in a solvent in the presence of a base. The method of the present invention will be described below.

[0031] Fullerene refers to a carbon cluster having a closed shell skeleton formed by arranging carbon atoms in a spherical or rugby shape. The fullerene used in the production method of the present invention is not particularly limited, and specifically includes C60, C70, C76, C78, ​​C82, C84, C90, C94, C96, and higher carbon clusters. These may be single or mixed. For example, C60 fullerene refers to a fullerene having 60 carbon atoms constituting the carbon skeleton, and C70 fullerene refers to a fullerene having 70 carbon atoms constituting the carbon skeleton.

[0032] The sulfone compound represented by formula (I) (hereinafter referred to as "sulfone compound (I)") is bonded to fullerene to enhance the compatibility of the fullerene with hole transport materials. An organic thin-film solar cell using the [6,6]methanofullerene derivative of the present invention bonded to the sulfone compound (I) has improved photoelectric conversion efficiency compared to that using the corresponding fullerene.

[0033] The amount of sulfone compound (I) used may be adjusted appropriately, but for example, it is preferably 0.8 times or more by mole, more preferably 1 times or more by mole, and more preferably 1.1 times or more by mole relative to the raw material fullerene. The upper limit of this ratio is not particularly limited, but it can be, for example, 10 times or less by mole, preferably 5 times or less by mole, and more preferably 2 times or less by mole.

[0034] The reaction according to the present invention is considered to be via an anion generated by reacting a base with the sulfone compound (I). The base to be used may be appropriately selected, and examples thereof include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; metal alkoxides such as sodium methoxide, sodium ethoxide, and potassium t-butoxide; alkali metal carbonates such as sodium carbonate, potassium carbonate, and cesium carbonate; amides such as sodium amide and lithium diisopropylamide; tertiary amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, trioctylamine, triphenylamine, tribenzylamine, trinaphthylamine, and triethanolamine; amidines such as diazabicycloundecene and diazabicyclononene; and guanidines such as guanidine salts.

[0035] The amount of base used may be adjusted appropriately, and may be, for example, 1 to 20 times the molar amount of the raw fullerene. The ratio is preferably 2 or more, more preferably 4 or more, and is preferably 15 or less or 10 or less, and more preferably 8 or less.

[0036] The solvent used in the present invention is not particularly limited as long as it exhibits appropriate solubility for the base, the sulfone compound (I) and the fullerene and does not inhibit the reaction. Examples of the solvent include aromatic hydrocarbon solvents such as toluene, chlorobenzene, dichlorobenzene, nitrobenzene and cyanobenzene; halogenated aliphatic hydrocarbon solvents such as dichloromethane, chloroform and dichloroethane; and aprotic polar solvents such as acetone, dimethylsulfoxide, dimethylformamide and dimethylacetamide.

[0037] The solvent may be used alone or in combination of two or more. For example, it is preferable to use a mixed solvent of an aromatic hydrocarbon solvent and an aprotic polar solvent, since the mixed solvent has an effect of accelerating and stabilizing the reaction.

[0038] The amount of the solvent used may be appropriately adjusted within a range in which the base, the sulfone compound (I), and the fullerene can be adequately dissolved, and may be, for example, about 30 mL or more and 100 mL or less per 1 g of the total of the base, the sulfone compound (I), and the fullerene.

[0039] The reaction conditions may be adjusted appropriately. According to the method of the present invention, the target compound, a methanofullerene derivative, can be produced under mild conditions in a short time. For example, the reaction temperature can be adjusted to -40°C or higher and 80°C or lower. The temperature is preferably 0°C or higher, more preferably 10°C or higher, even more preferably 15°C or higher, and is preferably 60°C or lower, and more preferably 40°C or lower. The reaction can also be carried out at room temperature without temperature control. The pressure during the reaction can be normal pressure as long as the temperature is within the above range.

[0040] The reaction time can be 30 minutes or more and 50 hours or less. The reaction time is preferably 1 hour or more, more preferably 5 hours or more, even more preferably 10 hours or more, and is preferably 40 hours or less, more preferably 30 hours or less, and even more preferably 20 hours or less. The actual reaction time can be determined by a preliminary experiment, or can be the time when consumption of any of the raw materials can be confirmed by thin layer chromatography or the like.

[0041] The gas phase in the reaction system may be replaced with an inert gas such as nitrogen gas or argon gas, but the reaction according to the present invention can also be carried out in an air atmosphere.

[0042] After the reaction is completed, a typical post-treatment may be carried out. For example, the reaction solution may be concentrated, and the target compound may be purified by HPLC, silica gel column chromatography, or the like. Alternatively, methanol or the like may be added to the reaction solution, and the precipitated crude product may be collected by filtration, and the target compound may be further purified.

[0043] The methanofullerene derivative obtained by the method of the present invention is a [6,6]methanofullerene derivative, i.e., has the following structure in which the carbon-carbon double bond at the portion where the six-membered rings constituting the fullerene are condensed is crosslinked with a methano group (>C<).

[0044] [ka]

[0045] [6,6] methanofullerene derivatives derived from spherical fullerenes such as C60 fullerenes do not have any isomers due to their symmetry, but [6,6] methanofullerene derivatives derived from C70 fullerenes and other fullerenes, when they have one substituent, exist as α-position isomers with the substituent on the long axis of the fullerene skeleton and β-position isomers with the substituent on the long axis of the fullerene skeleton.

[0046] As described above, in the case of [6,6] methanofullerene derivatives having isomers, it has been reported that the higher the ratio of one positional isomer, the higher the photoelectric conversion efficiency. According to the method of the present invention, as shown in the examples below, not only is the [6,6] methanofullerene derivative efficiently produced, but the ratio of the α-isomer is more than 98%, which is higher than could be achieved by conventional techniques. Therefore, the burden of purification to increase the ratio of the α-isomer is reduced. The sulfone compound represented by formula (II) according to the present invention is very useful as it enables the efficient production of [6,6] methanofullerene derivatives having excellent properties by the method of the present invention. EXAMPLES

[0047] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0048] Example 1: Preparation of [6,6]PC61BM (1) Preparation of (5-methoxy-5-oxo-1-phenylpentyl)trifluoromethylsulfone [ka] Benzyl trifluoromethylsulfone (904 mg) was added to a 100 mL eggplant flask and dissolved in dimethylformamide (30 mL). The resulting solution was cooled to 0°C, sodium hydride (192 mg) was added, and the mixture was stirred for 1 hour. A solution of methyl 4-bromobutyrate (797 mg) dissolved in dimethylformamide (3 mL) was added dropwise, and the mixture was stirred at room temperature for 6 hours. After the reaction was completed, dilute hydrochloric acid was added to the reaction solution, and the mixture was extracted with ethyl acetate. The organic layer was washed with water and saturated saline, and then dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography to obtain the target compound (yield: 63%, yield: 822 mg). 1H-NMR (600MHz, CDCl3): δ=7.45-7.43(m,5H),4.39-4.35(m,1H),3.65(s,3H),2.94-2.20(m,4H),1.58-1.51(m,2H)

[0049] (2)[6,6]Manufacture of PC61BM [ka] C60 (29 mg) was added to a 25 mL two-neck flask and dissolved in o-dichlorobenzene (4 mL), followed by the addition of (5-methoxy-5-oxo-1-phenylpentyl)trifluoromethylsulfone (14 mg) and dimethylsulfoxide (2 mL). Cesium carbonate (39 mg) was then added and the mixture was stirred at room temperature for 15 hours. Acetic acid and water were added to the reaction solution, followed by extraction with toluene. The organic layer was washed with saturated saline and dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography to obtain the target compound (yield: 63%, yield: 23 mg). The resulting product is 1 H-NMR analysis and comparison with the spectral data in Non-Patent Document 2 confirmed that the compound was [6,6]PC61BM. 1 H-NMR (600MHz, CDCl3): δ=7.91(d,J=8.7Hz,2H),7.60-7.43(m,3H),3.68(s,3H),2.94-2.87(m,2H),2.52(t,J=7.5Hz,2H),2.23-2.12(m,2H)

[0050] Test Example 1: Stability test The stability of the sulfone compounds was tested under the following conditions. Terephthalonitrile was added as an internal standard to the sulfone compound ((5-methoxy-5-oxo-1-phenylpentyl)trifluoromethylsulfone) produced in Example 1(1), and the mixture was dissolved in about 1 mL of deuterated chloroform. The obtained sample solution was stored at 25° C. and the change in the concentration over time was measured. 1The residual ratio of the sulfone compound was calculated from the proton ratio with respect to the internal standard substance by H-NMR. The results are shown in Table 1. For comparison, the residual rate of the sulfonium salt was also determined in the same manner for the sulfonium salt (dipropyl(5-methoxy-5-oxo-1-phenylpentyl)sulfonium tetrafluoroborate) described in Patent Document 4. The results are shown in Table 1.

[0051] [Table 1]

[0052] As shown in the results in Table 1, the sulfonium salt decomposed over time, and the residual rate after 7 days decreased to 74%. In contrast, the sulfone compound did not decompose at all, and the remaining rate was the same as at the time of preparation even after 7 days. These results indicate that sulfone compounds are more stable than sulfonium salts.

[0053] Example 2: Preparation of [6,6]PC71BM [ka] In a 25 mL two-neck flask, (5-methoxy-5-oxo-1-phenylpentyl)trifluoromethylsulfone (14 mg) prepared in Example 1 (1) was dissolved in dimethylsulfoxide (4 mL). Sodium hydride (2.2 mg) was added and stirred for 15 minutes, and then a solution of C70 (25 mg) dissolved in o-dichlorobenzene (12 mL) was added and stirred at room temperature for 18 hours. Acetic acid and water were added to the reaction solution, which was then extracted with toluene. The organic layer was washed with saturated saline and dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography to obtain the target compound (yield: 61%, yield: 19 mg). The obtained product was 1The compound was analyzed by H-NMR and compared with the spectral data in Non-Patent Document 3, and was confirmed to be [6,6]PC71BM. As for the isomer ratio, as shown in FIG. 1, the proportion of the α-isomer was confirmed to be 99.5% or more. 1 H-NMR (600MHz, CDCl3):δ=7.92-7.40(m,5H),3.74(β-type,s,0.00743H),3.67(α- type,s,2.99H),3.50(β-type,s,0.00718H),2.53-2.42(m,4H),2.25-1.99(m,2H)

[0054] Example 3: Preparation of 4-Methoxy-[6,6]-PC61BM (1) Preparation of {5-methoxy-5-oxo-1-(4-methoxyphenyl)pentyl}trifluoromethylsulfone [ka] 4-Methoxybenzyl trifluoromethylsulfone (254 mg) was added to a 100 mL eggplant flask and dissolved in dimethylsulfoxide (5 mL). Sodium t-butoxide (115 mg) was then added and stirred for 30 minutes. A solution of 4-methyl iodobutyrate (273 mg) dissolved in dimethylsulfoxide (1 mL) was added dropwise and stirred at room temperature for 18 hours. After the reaction was completed, dilute hydrochloric acid was added to the reaction solution and extracted with ethyl acetate. The organic layer was washed with water and saturated saline, and then dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography to obtain the target compound (yield: 37%, yield: 130 mg). 1 H-NMR (600MHz, CDCl3): δ=7.31(d,J=7.8Hz,2H),6.94(d,J=9.0Hz,2H),4.34(dd,J=4.2Hz and 11.4Hz,1H),3.82(s,3H),3.65(s,3H),2.40-2.18(m,4H),1.61-1.51(m,2H)

[0055] (2) Preparation of 4-Methoxy-[6,6]-PC61BM [ka] C60 (72 mg) was added to a 25 mL two-neck flask and dissolved in o-dichlorobenzene (4 mL), followed by the addition of {5-methoxy-5-oxo-1-(4-methoxyphenyl)pentyl}trifluoromethylsulfone (43 mg) and dimethylsulfoxide (2 mL). Cesium carbonate (98 mg) was added to the solution and stirred at room temperature for 18 hours. Acetic acid and water were then added, followed by extraction with toluene. The organic layer was washed with saturated saline and dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography to obtain the target compound (yield: 56%, yield: 53 mg). The product obtained was 1 The compound was analyzed by H-NMR and confirmed to be 4-methoxy-[6,6]PC61BM by comparison with the spectral data in a non-patent document (FB Kooistra, et al., Org. Lett., 2007, 9, 551). 1 H-NMR (600MHz, CDCl3): δ=7.82(d,J=8.4Hz,2H),7.05(d,J=9.0Hz,2H),3.89 (s,3H),3.67(s,3H),2.88-2.84(m,2H),2.54-2.50(m,2H),2.19-2.15(m,2H)

[0056] Example 4: Preparation of 4-methoxyphenyl-[6,6]methanofullerene (1) Preparation of 4-Methoxybenzyl trifluoromethylsulfone [ka] In a 100 mL eggplant flask, 4-methoxybenzyl chloride (1.56 g), sodium trifluoromethanesulfonate (1.72 g), and tetrabutylammonium iodide (1.11 g) were added and dissolved in acetonitrile (20 mL). The solution was stirred at 70°C for 6 hours, and the reaction solvent was then distilled off under reduced pressure. Water was added to the concentrated residue, which was then extracted with ethyl acetate. The organic layer was washed with water and saturated saline, and then dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography to obtain the target compound (yield: 67%, yield: 1.71 g). 1 H-NMR (600MHz, CDCl3): δ=7.33(d,J=8.4Hz,2H),6.95(d,J=8.4Hz,2H),4.42(s,2H),3.82(s,3H)

[0057] (2) Preparation of 4-methoxyphenyl-[6,6]methanofullerene [ka] 4-Methoxybenzyl trifluoromethylsulfone (31 mg) was added to a 25 mL two-neck flask and dissolved in dimethylsulfoxide (2 mL), followed by the addition of sodium hydride (4.8 mg). The solution was stirred at room temperature for 1 hour, and then added to a solution of C60 (72 mg) dissolved in o-dichlorobenzene (10 mL), and stirred for 18 hours. Acetic acid and water were added to the reaction solution, which was then extracted with toluene. The organic layer was washed with saturated saline and dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography to obtain the target compound (yield: 28%, yield: 24 mg). The product obtained was 1 The fullerene was analyzed by 1 H-NMR and confirmed to be 4-methoxyphenyl-[6,6]methanofullerene by comparison with the spectral data in a non-patent document (M. Prato, et al., J. Am. Chem. Soc., 1993, 115, 8479). 1H-NMR (600MHz, CDCl3): δ=7.87(d,J=8.4Hz,2H),7.04(d,J=6.6Hz,2H),5.35(s,1H),3.80(s,3H)

[0058] Example 5: Preparation of 1-(benzo[b]thiophen-2-yl)-[6,6]methanofullerene (1) Preparation of 2-(trifluoromethylsulfonyl)methyl-benzo[b]thiophene [ka] 2-Chloromethyl-benzo[b]thiophene (390 mg), sodium trifluoromethanesulfonate (390 mg), and tetrabutylammonium iodide (369 mg) were added to a 100 mL eggplant-shaped flask and dissolved in dimethylformamide (10 mL). The solution was stirred at 60°C for 15 hours, and the reaction solvent was distilled off under reduced pressure. Water was added to the concentrated residue, which was then extracted with ethyl acetate. The organic layer was washed with water and saturated saline, and then dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was filtered off, and the filtrate was concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography to obtain the target compound (yield: 70%, yield: 412 mg). 1 H-NMR (600MHz, CDCl3): δ=7.85-7.80(m,2H),7.49(s,1H),7.42-7.39(m,2H),4.78(s,2H)

[0059] (2) Preparation of 1-(benzo[b]thiophen-2-yl)-[6,6]methanofullerene [ka] C60 (36 mg) was added to a 25 mL two-neck flask and dissolved in o-dichlorobenzene (3 mL), followed by the addition of 2-(trifluoromethylsulfonyl)methylbenzo[b]thiophene (17 mg) and dimethyl sulfoxide (1 mL). Cesium carbonate (49 mg) was then added and stirred at room temperature for 15 hours. Methanol was added to the reaction solution, and the mixture was centrifuged to obtain a crude product. The crude product was subjected to column chromatography to obtain the target compound (yield: 20%, yield: 9 mg). 1 H-NMR (600MHz, CDCl3): δ=7.90(dd,J=7.8 and 16.8Hz,2H),7.81(s,1H),7.46-7.35(m,2H),5.46(s,1H)

Claims

1. A method for producing a [6,6] methanofullerene derivative, comprising the steps of: A method comprising the step of reacting a sulfone compound represented by the following formula (I) with a fullerene in the presence of a base in a solvent: 【Chemistry 1】 [In the formula, R 1 represents a trifluoromethyl group, R 2 C which may have a substituent β 6-30 represents an aryl group or an aromatic heterocyclic group which may have a substituent β, R 3 is H or -X-C(=O)O-R 4 (wherein X is a single bond or C 1-10 R represents an alkanediyl group; 4 C which may have a substituent α 1-30 C which may have an alkyl group or a substituent α 2-30 Alkenyl group, C optionally having a substituent α 2-30 Alkynyl group, C optionally having a substituent β 6-30 represents an aryl group, an aromatic heterocyclic group which may have a substituent β, or a polyalkylene glycol group; The substituent α is C 1-6 Alkoxy group, C 6-12 Aryl group, C 1-7 represents one or more substituents selected from the group consisting of an alkanoyl group, an amino group, a halogeno group, a hydroxyl group, a nitro group, and a cyano group, The substituent β is C 1-6 Alkyl group, C 1-6 Alkoxy group, C 6-12 Aryl group, C 1-7 represents one or more substituents selected from the group consisting of an alkanoyl group, an amino group, a halogeno group, a hydroxyl group, a nitro group, and a cyano group.]

2. 2. The method of claim 1, wherein the fullerene is a C60 fullerene or a C70 fullerene.

3. The method according to claim 1 or 2, wherein the fullerene is a C70 fullerene, and the proportion of α-isomers in the [6,6] methanofullerene derivative produced by the reaction is greater than 99%.

4. 4. The method according to claim 1, wherein the solvent is a mixed solvent of an aromatic hydrocarbon solvent and an aprotic polar solvent.

5. 5. The process of claim 4, wherein the aromatic hydrocarbon solvent is dichlorobenzene.

6. 6. The method according to claim 4 or 5, wherein the aprotic polar solvent is dimethylsulfoxide and / or dimethylformamide.

7. R 2 The method according to any one of claims 1 to 6, wherein is a phenyl group which may have a substituent β.

8. R 4 The method according to any one of claims 1 to 7, wherein is a methyl group.

9. A [6,6] methanofullerene-forming agent for fullerene, comprising a sulfone compound represented by the following formula (II): 【Chemistry 2】 [In the formula, R 1 represents a trifluoromethyl group, R 2 C which may have a substituent β 6-30 represents an aryl group or an aromatic heterocyclic group which may have a substituent γ, R 4 C which may have a substituent α 1-30 C which may have an alkyl group or a substituent α 2-30 Alkenyl group, C optionally having a substituent α 2-30 Alkynyl group, C optionally having a substituent β 6-30 represents an aryl group, an aromatic heterocyclic group which may have a substituent β, or a polyalkylene glycol group, n is an integer of 3 or more and 5 or less, The substituent α is C 1-6 Alkoxy group, C 6-12 Aryl group, C 1-7 represents one or more substituents selected from the group consisting of an alkanoyl group, an amino group, a halogeno group, a hydroxyl group, a nitro group, and a cyano group, The substituent β is C 1-6 Alkyl group, C 1-6 Alkoxy group, C 6-12 Aryl group, C 1-7 represents one or more substituents selected from the group consisting of an alkanoyl group, an amino group, a halogeno group, a hydroxyl group, a nitro group, and a cyano group, The substituent γ represents one or more substituents selected from the group consisting of a halogeno group, a nitro group, and a cyano group.

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