JPWO2004106348A1 - Aminomethyl-substituted fluorothiazolobenzimidazole derivatives - Google Patents

Abstract

The present invention relates to the provision of a novel aminomethyl-substituted fluorothiazolobenzimidazole derivative represented by the following general formula (I) or a salt thereof. It has been found that the derivative or a salt thereof has a metabotropic glutamate receptor action and is excellent in oral activity and useful as a medicine. (Here, the symbols in the formula represent the following meanings: R1: optionally substituted oxygen-containing saturated heterocycle-, optionally substituted sulfur-containing saturated heterocycle-, optionally substituted cycloalkyl, R6-O-, or R7-S-; Alk1: lower alkylene; m: 0 or 1; Alk2: lower alkylene optionally substituted with an oxo group; n: 0 or 1; X: bond, O, S, or -NR5-; R3: H, lower alkyl, halogeno lower alkyl, lower alkenyl, lower alkynyl, optionally substituted cycloalkyl, cyano, or saturated heterocycle-; R2, R4, R5, R6 and R7: the same or different H or lower alkyl)

Description

  The present invention relates to a novel aminomethyl-substituted fluorothiazolobenzimidazole derivative or a salt thereof useful as a medicine.

Glutamate acts as a neurotransmitter in the mammalian central nervous system (Mayer ML and Westbrook GL, Prog. Neurobiol., 28 (1987) 197-276). Recent studies have revealed the importance of glutamate in higher brain function. Glutamate is released from nerve endings and regulates neuronal activity or neurotransmitter release via glutamate receptors present in the postsynaptic membrane or nerve endings. Glutamate receptors are currently classified into two major categories based on various pharmacological and physiological studies. One is a receptor with a built-in ion channel, and the other is a metabotropic receptor (Hollmann M. and Heinemann S., Annu. Rev. Neurosci., 17 (1994) 31. −108).
Molecular biological studies have reported that metabotropic glutamate receptors (hereinafter sometimes referred to as mGluR) currently have at least eight different subtypes of mGluR1 to mGluR8. mGluR is coupled to phospholipase C through the G protein to promote the production of inositol triphosphate (IP3) and the mobilization of calcium ions into the cell (Group I: mGluR1 and mGluR5), and the Gi protein And receptors that suppress cAMP production (Group II: mGluR2, mGluR3, Group III: mGluR4, mGluR6, mGluR7 and mGluR8). These receptors have different brain distributions. For example, mGluR6 does not exist in the brain but exists only on the retina, and it is speculated that each receptor plays a different physiological role ( Nakanishi S., Neuron 13 (1995) 1031-1037).
So far, a compound selective for mGluR has been reported as compared with an ion channel-containing glutamate receptor (Hayashi Y. et al., Br. J. Pharmacol. 107 (1992) 539-543; Hayashi Y. et. al., J. Neurosci. 14 (1995) 3370-3377), and the relationship between mGluR and various pathological conditions has been reported in the following (1) to (6) by studies using these compounds.
(1) Epilepsy is induced by administration of (1S, 3R) -1-aminocyclopentane-1,3-dicarboxylic acid (hereinafter referred to as (1S, 3R) -ACPD) which is an mGluR agonist (Tizzano J. et al. P. et al., Neurosci. Lett., 162 (1993) 12-16; McDonald JW et al., J. Neurosci., 13 (1993) 4445-4455). Furthermore, the effectiveness of (S) -4-carboxy-3-hydroxyphenylglycine (hereinafter referred to as (S) -CHPG), which is an antagonist of mGluR1 and an agonist of mGluR2, in various epilepsy models has been reported. (Dalby, N.O. & Thomsen, C. J. Pharmacol. Exp. Ther., 276 (1996) 516-522).
(2) It has been proved by electrophysiological experiments that mGluR is involved in the transmission of painful stimuli to spinal dorsal horn neurons (Young, MR et al., Neuropharmacology, 33 (1994) 141-144). Ibid, 34 (1995) 1033-1041). Furthermore, it has been reported that (S) -CHPG has the effect of slowing the avoidance response of thermal and mechanical pain sensation in rats (Young, MR et al., Br. J. Pharmacol., 114 (1995) 316P).
(3) When (1S, 3R) -ACPD or (RS) -3,5-dihydroxyphenylglycine (hereinafter referred to as 3,5-DHPG) is administered to a mouse or rat brain parenchyma in a trace amount or systemically, accompanied by convulsions, It has been reported to cause neuronal cell death (Lipartit, M. et al., Life Sci., 52 (1993) PL85-90; McDonald, JW et al., J. Neurosci., 13 (1993). ) 4445-4455; Tizzano, JP, et al., Neuropharmacology, 34 (1995) 1063-3067). This is thought to result from the activation of mGluR1 and mGluR5.
(4) It is well known that dependence is formed by chronic administration of benzodiazepines. On days 2 and 3 after 7-day continuous administration of benzodiazepine, it was reported that (1S, 3R) -ACPD mGluR-mediated inositol phospholipid turnover was increased, It has been suggested that mGluR is involved in expression (Mortensen, M. et al., J. Pharmacol. Exp. Ther., 274 (1995) 155-163).
(5) N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced black by intracerebroventricular administration of 1-aminoindan-1,5-dicarboxylic acid, an mGluR group I antagonist Dopamine neuronal cell death has been reported to be suppressed (Aguirre, JA et al., Neuroport. 12 (2001) 2615-2617).
(6) It has been reported that an antagonist of mGluR1 suppresses protein leakage outside the dural blood vessel by trigeminal ganglion electrical stimulation (WO01 / 32632).
That is, the above report shows that the compound acting on mGluR1 is useful for epilepsy, pain, suppression of neuronal cell death, benzodiazepine withdrawal syndrome, and migraine.
Moreover, since the effectiveness of an mGluR1 antagonist has been confirmed in a rat cerebral infarction model, it is considered that the mGluR1 antagonist is useful as a prophylactic / therapeutic agent for cerebral infarction (Patent Document 1).
Furthermore, since mGluR1 antagonist was confirmed to improve the decrease in pain threshold in neuropathic pain model, postherpetic neuralgia, pain associated with diabetic neuropathy, cancer pain, postoperative chronic pain, etc. It is also useful as a therapeutic agent for neuropathic pain (Patent Document 2).
As compounds having mGluR1 antagonistic activity, the above Patent Documents 1, 2, 3 and Patent Document 4 disclose thiazolobenzimidazole derivatives. In Patent Document 4, the benzene ring of thiazolobenzimidazole is bromine and A compound substituted with an amino group is disclosed (Example 90). However, the thiazolobenzimidazole derivatives of the present invention in which the benzene ring is substituted with a fluorine atom and an aminomethyl group have no specific disclosure in these documents.
In addition, the thiazolobenzimidazole derivatives disclosed in Patent Documents 1, 3 and 4 above are compounds in which cerebral infarction, which is the main administration form of parenteral administration, has been found as a main indication, and therefore have oral activity. There were problems such as not enough.
On the other hand, Patent Document 2 reports that a thiazolobenzimidazole derivative in which an amino group is substituted on the benzene ring part of a thiazolobenzimidazole ring has a therapeutic effect on neuropathic pain by oral administration.
However, these compounds have a problem in safety due to the chemical structure having an amino group (aniline amino group) on the benzene ring.
PCT International Publication Pamphlet WO99 / 44639 PCT International Publication Pamphlet WO01 / 08705 PCT International Publication Pamphlet WO00 / 59913 JP 2000-351882 A

（ここに、式中の記号は、以下の意味を表す。
Ｒ^１：置換されてもよい含酸素飽和ヘテロ環−、置換されてもよい含硫黄飽和ヘテロ環−、置換されてもよいシクロアルキル、Ｒ^６−Ｏ−、又はＲ^７−Ｓ−
Ａｌｋ１：低級アルキレン
ｍ：０又は１
Ａｌｋ２：オキソ基で置換されてもよい低級アルキレン
ｎ：０又は１
Ｘ：結合、Ｏ、Ｓ、又はＮＲ^５
Ｒ^３：Ｈ、低級アルキル、ハロゲノ低級アルキル、低級アルケニル、低級アルキニル、置換されてもよいシクロアルキル、シアノ、又は飽和ヘテロ環−
Ｒ^２、Ｒ^４、Ｒ^５、Ｒ^６及びＲ^７：同一又は異なって、Ｈ、又は、低級アルキル）
（２）一般式（Ｉ）において、Ｒ^１がオキセタン−又はジオキソラン−、Ｒ^２がＨ、Ｒ^３がネオペンチル、Ｘが結合、Ｒ^４がメチル、Ａｌｋ１がメチレン、及びｎが０である、前記（１）記載の誘導体又はその塩。
（３）５−フルオロ−Ｎ−メチル−Ｎ−ネオペンチル−６−［（オキセタン−３−イルアミノ）メチル］チアゾロ［３，２−ａ］ベンゾイミダゾール−２−カルボキサミド；
６−｛［（１，３−ジオキソラン−２−イルメチル）アミノ］メチル｝−５−フルオロ−Ｎ−メチル−Ｎ−ネオペンチルチアゾロ［３，２−ａ］ベンゾイミダゾール−２−カルボキサミド；又はその塩。
（４）前記（１）乃至（３）記載のアミノメチル置換フルオロチアゾロベンゾイミダゾール誘導体又はその製薬学的に許容される塩を有効成分とする医薬組成物。
（５）前記（１）乃至（３）記載のアミノメチル置換フルオロチアゾロベンゾイミダゾール誘導体又はその製薬学的に許容される塩を有効成分とする神経因性疼痛治療剤。
（６）前記（１）乃至（３）記載のアミノメチル置換フルオロチアゾロベンゾイミダゾール誘導体又はその製薬学的に許容される塩及び担体からなる医薬組成物の有効量を患者に投与することによる神経因性疼痛の治療方法。
好ましくは、前記（１）乃至（３）記載のアミノメチル置換フルオロチアゾロベンゾイミダゾール誘導体又はその製薬学的に許容される塩を有効成分とする神経の圧迫により生ずる神経因性疼痛治療剤、更に好ましくは、遺伝子突然変異誘発性のない前記（１）乃至（３）記載のアミノメチル置換フルオロチアゾロベンゾイミダゾール誘導体又はその製薬学的に許容される塩を有効成分とする神経因性疼痛治療剤である。
本発明は更に、上記（１）乃至（３）記載のアミノメチル置換フルオロチアゾロベンゾイミダゾール誘導体又はその塩を有効成分として含有するｍＧｌｕＲ１受容体拮抗剤に関する。An object of the present invention is to provide a novel aminomethyl-substituted fluorothiazolobenzimidazole derivative and a salt thereof clinically useful as a metabotropic glutamate receptor antagonist having excellent oral activity.
Moreover, although the compound of the said patent document 2 has oral activity, it is confirmed by our research that it has gene mutagenicity. This gene mutagenesis is considered to be expressed by structural features having an aniline amino group, and compounds having an aniline amino group may have carcinogenicity even though they have oral activity. As a disadvantage, it cannot be used clinically.
For this reason, the compound which does not have an aniline amino group and was excellent in oral activity was required. However, the activity of the compounds having no aniline amino group shown in Patent Documents 1, 3, and 4 is not sufficient.
As a result of intensive research aimed at achieving the above-mentioned problems, the present inventors have found that a benzene ring of a thiazolobenzimidazole derivative is substituted with a fluorine atom and a substituted aminomethyl and does not have an aniline amino group as a substituent. Zorobenzimidazole derivatives, particularly aminomethyl-substituted thiazolobenzimidazole derivatives in which the benzene ring has fluorine and an oxygen-containing heterocycle are described in Patent Documents 1, 3, and 4 in which the conventionally known fluorine atom is not substituted. Compared to thiazolobenzimidazole derivatives, it has better activity on metabotropic glutamate receptors, no risk of carcinogenicity, and superior oral activity, especially for neuropathic pain caused by nerve compression The present inventors have found an unexpected effect having oral activity and have completed the present invention.
That is, the present invention relates to an aminomethyl-substituted fluorothiazolobenzimidazole derivative represented by the following general formula (I) or a salt thereof, and a pharmaceutical comprising them as an active ingredient.
Specifically, it is as shown below.
(1) An aminomethyl-substituted fluorothiazolobenzimidazole derivative represented by the following general formula (I) or a salt thereof.

(Here, the symbols in the formula have the following meanings.
R ¹ : optionally substituted oxygen-containing saturated heterocycle-, optionally substituted sulfur-containing saturated heterocycle-, optionally substituted cycloalkyl, R ⁶ -O-, or R ⁷ -S-
Alk1: Lower alkylene m: 0 or 1
Alk2: Lower alkylene which may be substituted with an oxo group n: 0 or 1
X: Bond, O, S, or NR ⁵
R ³ : H, lower alkyl, halogeno lower alkyl, lower alkenyl, lower alkynyl, optionally substituted cycloalkyl, cyano, or saturated heterocyclic ring
R ² , R ⁴ , R ⁵ , R ⁶ and R ⁷ : the same or different, H or lower alkyl)
(2) In the general formula (I), R ¹ is oxetane- or dioxolane, R ² is H, R ³ is neopentyl, X is bonded, R ⁴ is methyl, Alk1 is methylene, and n is 0, (1) The derivative or its salt as described.
(3) 5-fluoro-N-methyl-N-neopentyl-6-[(oxetane-3-ylamino) methyl] thiazolo [3,2-a] benzimidazole-2-carboxamide;
6-{[(1,3-dioxolan-2-ylmethyl) amino] methyl} -5-fluoro-N-methyl-N-neopentylthiazolo [3,2-a] benzimidazole-2-carboxamide; salt.
(4) A pharmaceutical composition comprising the aminomethyl-substituted fluorothiazolobenzimidazole derivative or the pharmaceutically acceptable salt thereof according to any one of (1) to (3) as an active ingredient.
(5) A therapeutic agent for neuropathic pain comprising the aminomethyl-substituted fluorothiazolobenzimidazole derivative or the pharmaceutically acceptable salt thereof according to (1) to (3) as an active ingredient.
(6) Nerve obtained by administering to a patient an effective amount of a pharmaceutical composition comprising the aminomethyl-substituted fluorothiazolobenzimidazole derivative or the pharmaceutically acceptable salt and carrier thereof according to (1) to (3) above. For the treatment of pathogenic pain.
Preferably, a therapeutic agent for neuropathic pain caused by nerve compression comprising the aminomethyl-substituted fluorothiazolobenzimidazole derivative or the pharmaceutically acceptable salt thereof described in (1) to (3) above as an active ingredient, Preferably, a therapeutic agent for neuropathic pain comprising, as an active ingredient, the aminomethyl-substituted fluorothiazolobenzimidazole derivative or the pharmaceutically acceptable salt thereof described in (1) to (3) above, which is not gene-mutable. It is.
The present invention further relates to an mGluR1 receptor antagonist comprising, as an active ingredient, the aminomethyl-substituted fluorothiazolobenzimidazole derivative or salt thereof described in (1) to (3) above.

以下に、各製法について説明する。
製法１：４−アミノ−５−ブロモ−２−フルオロ−３−ニトロ安息香酸誘導体の製造

（式中Ｒ^８は水素または低級アルキル、Ｒ^９はＣｌ、Ｂｒ、Ｉを示す。）
製法１はアニリン誘導体からニトロアニリン誘導体の製造法である。
工程１はベンゼン環のハロゲン化である。すなわち（ＩＩ）を四塩化炭素、クロロホルム、塩化メチレン、１，４−ジオキサン、ＤＭＦ、ＤＭＳＯ、メタノール、酢酸等の溶媒中、臭素、臭化水素、テトラブチルアンモニウムトリブロミド等のアンモニウム錯体、Ｎ−ブロモスクシンイミド、塩素、Ｎ−クロロスクシンイミド等のハロゲン化剤と氷冷から加温条件で反応させることで（ＩＩＩ）を製造できる。
工程２はアミノ基のアシル化である。すなわち（ＩＩＩ）をＴＨＦ、クロロホルム、ジエチルエーテル、ＤＭＦ、アセトニトリル等の不活性溶媒中、またはピリジン等の活性溶媒中、酸ハライド、酸無水物、活性エステル等のアシル化剤と、低温から加温条件で反応させることで（ＩＶ）を製造できる。
工程３はベンゼン環のニトロ化である。すなわち（ＩＶ）を硫酸、酢酸等の溶媒中、硝酸、硝酸カリウム、硝酸アセチル等のニトロ化剤と、または硝酸を溶媒に用いて、低温から室温条件で、さらに必要に応じて加温条件で反応させることで（Ｖ）を製造できる。また、トルエン、アセトニトリル、ＴＨＦ、スルホラン等の不活性溶媒中、ニトロニウムテトラフルオロボレート等のニトロ化剤を用いて、低温から室温条件で、さらに必要に応じて加温条件で反応させることでも（Ｖ）を製造できる。
工程４は加水分解による脱アシル反応である。すなわち（Ｖ）を酸性条件あるいはアルカリ性条件下で加水分解反応させることで（ＶＩ−ａ）を製造できる。酸性条件の場合は、硫酸、塩酸、酢酸等を用いて、またアルカリ性条件の場合は、水酸化ナトリウム、水酸化カリウム、炭酸カリウム等を用いて、メタノール、エタノール、ＴＨＦ、アセトニトリル、水等の溶媒、それらの混合溶媒、または無溶媒で、室温から加温条件で反応を行う。
製法２：４−アミノ−２−フルオロ−５−ニトロ安息香酸誘導体の製造

製法２はフルオロベンゼン誘導体からイプソ反応によるアミノベンゼン誘導体の製造法である。すなわち（ＶＩＩ）をエタノール、イソプロパノール等のアルコール系溶媒、ＤＭＦ、ＤＭＳＯ、水等の溶媒中、塩化アンモニウム等のアミン供与剤またはアンモニアと室温から加温条件で反応させることで（ＶＩ−ｂ）を製造できる。
製法３：チオキソベンゾイミダゾール環の製造

製法２はニトロアニリン誘導体からチオキソベンゾイミダゾール環の製造法である。
工程１は還元反応である。すなわち（ＶＩ）をメタノール、エタノール、ＤＭＦ等の不活性溶媒中、水素雰囲気下、またはギ酸アンモニウム等の水素供与剤の存在下に、パラジウム等の金属触媒を用いて接触還元反応することで（ＶＩＩＩ）を製造できる。また、Ｒ９が水素の場合には、酢酸、塩酸、塩化アンモニウム等の酸性条件下、鉄、塩化第一スズ等を用いて反応するか、あるいは、水およびメタノール、エタノール、ＴＨＦ等の混合溶媒中、ヒドロサルファイトナトリウム等の還元剤を用いて、室温から加温条件で反応させることでも（ＶＩＩＩ）を製造できる。
工程２はチオキソベンゾイミダゾール環の環化反応である。すなわち（ＶＩＩＩ）をメタノール、エタノール、ＤＭＦ等の不活性溶媒中、トリエチルアミン等の塩基存在あるいは非存在下、二硫化炭素、１，１’−チオカルボニルジイミダゾール、チオ炭酸エステル等と反応させることで（ＩＸ）を製造できる。
さらに、工程１において接触還元反応を行った場合は、引き続き工程２を行うこともできる。
製法４：チアゾロベンゾイミダゾール環の製造

製法４はチオキソベンゾイミダゾール環からチアゾロベンゾイミダゾール環の製造法である。
工程１はアルキル化反応である。すなわち（ＩＸ）とα−ハロ酢酸誘導体とをエタノール、メタノール等のアルコール系溶媒、あるいはＤＭＦ、ＴＨＦ、アセトニトリル等の不活性溶媒中、ナトリウムメトキシド、ナトリウムエトキシド、水酸化ナトリウム、水酸化カリウム、水素化ナトリウム、炭酸カリウム、炭酸水素ナトリウム等の塩基存在または非存在下、室温から加温条件にて反応させることで（Ｘ）を製造できる。
工程２は環化反応である。すなわち（Ｘ）とギ酸エステル、ギ酸無水物等のホルミル化剤とをエタノール、メタノール等のアルコール系溶媒、あるいはＤＭＦ、ＴＨＦ、アセトニトリル等の不活性溶媒中、ナトリウムエトキシド、カリウムエトキシド、水酸化ナトリウム、水素化ナトリウム、ピリジン、トリエチルアミン等の塩基条件下、室温から加温条件にて反応させることで（ＸＩ）を製造できる。この（ＸＩ）は溶液状態では式１の平衡状態をとることもある。

工程３はジヒドロチアゾロベンゾイミダゾール環の異性化反応である。すなわち（ＸＩ）を溶液または懸濁液状態で式１に示す平衡混合物とした後、これを塩酸、硫酸、酢酸、トリフルオロ酢酸等の酸性条件で処理することで（ＸＩＩ）を析出させることができる。
工程４はジヒドロチアゾロベンゾイミダゾール環からチアゾロベンゾイミダゾール環への脱水反応である。すなわち（ＸＩＩ）を濃硫酸、酢酸、トリフルオロ酢酸等の酸と室温から加温条件にて反応させることで（ＸＩＩＩ）を製造できる。また、トルエン、ベンゼン等の不活性溶媒中、ｐ−トルエンスルホン酸、カンファースルホン酸等の酸性条件下、必要に応じてモレキュラーシーブス等の脱水剤の存在下または、Ｄｅａｎ−Ｓｔａｒｋ脱水装置等での脱水反応条件下、室温から加温条件にて反応させることでも（ＸＩＩＩ）を製造できる。
製法５：カルボン酸の還元

製法５は通常のカルボン酸の還元によるアルコール体の製造法である。すなわち（ＸＩＩＩ−ａ）を酸ハライド、酸無水物、活性エステル等の反応活性体へと誘導し、これを水素化ホウ素ナトリウム、水素化ホウ素テトラブチルアンモニウム等のホウ酸塩と反応させることで（ＸＩＶ）を製造できる。
製法６：エステルの加水分解

製法６はエステルの加水分解である。すなわち（ＸＩＶ）を酸性条件あるいはアルカリ性条件下で加水分解反応させることで（ＸＶ）を製造できる。酸性条件の場合は、硫酸、塩酸、酢酸等を用いて、またアルカリ性条件の場合は、水酸化ナトリウム、水酸化カリウム、炭酸カリウム等を用いて、メタノール、エタノール、ＴＨＦ、アセトニトリル、水等の溶媒、それらの混合溶媒、または無溶媒で、室温から加温条件で反応を行う。
製法７：アミド化

製法７はカルボン酸の通常のアミド化反応である。すなわち（ＸＶ）をＤＭＦ、ＴＨＦ、１，２−ジクロロエタン、クロロホルム等の不活性溶媒中、ジシクロヘキシルカルボジイミド、１−エチル−３−（３−ジメチルアミノプロピル）カルボジイミド、ジフェニルホスホリルトリアジド、１，１’−カルボニル−１Ｈ−イミダゾール、１−ヒドロキシベンゾトリアゾール等の縮合剤により活性化し、この活性体と対応するアミンとを反応させることで（ＸＶＩ）を製造できる。カルボン酸の活性化として、塩化チオニルやオキザリルクロリド等による酸塩化物法、酸無水物法、オキシ塩化リン等による活性リン酸エステル法等も用いることが出来る。
製法８：アルコールの酸化

製法８はアルコールのアルデヒドへの酸化反応である。すなわち（ＸＶＩ）をＤＭＳＯを溶媒に用いて、三酸化硫黄・ピリジン錯体と氷冷から室温条件で反応させることで（ＸＶＩＩ）を製造できる。またＳＷＥＲＮ酸化、クロム酸酸化、過マンガン酸酸化等の通常の酸化反応でも（ＸＶＩＩ）を製造できる。
製法９：還元的アミノ化

（ＸＶＩＩ）から（Ｉ）は通常の還元的アミノ化反応である。すなわち（ＸＶＩＩ）を、塩化メチレン、１，２−ジクロロエタン、クロロホルム、ＴＨＦ、メタノール、エタノール等の溶媒中、必要に応じて酢酸、塩酸等の酸触媒、またはチタニウムテトライソプロポキシド等のルイス酸存在下、対応するアミンとトリアセトキシ水素化ホウ素ナトリウム、シアノ水素化ホウ素ナトリウム、水素化ホウ素ナトリウム等の還元剤を用いて反応させることで（Ｉ）を製造できる。（Ｉ）は（ＸＶＩＩ）と対応するアミンとをトルエン、ベンゼン等の不活性溶媒中、必要に応じてモレキュラーシーブス等の脱水剤、またはＤｅａｎ−Ｓｔａｒｋ脱水装置等での脱水反応条件下、室温から加温条件下で反応させイミンとし、これをメタノール、エタノール等の溶媒中、または上記反応溶媒との混合溶媒中、水素化ホウ素ナトリウム等の還元剤で処理することでも製造できる。また上記還元剤を用いる代わりに通常の接触還元条件、具体的には水素雰囲気下、パラジウム等の金属触媒を用いても（Ｉ）を製造できる。
水酸基、アミノ基およびエステル基等の一般的な保護基等については、ＰＲＯＴＥＣＴＩＶＥ ＧＲＯＵＰＳ ＩＮ ＯＲＧＡＮＩＣ ＳＹＮＴＨＥＳＩＳ、ＴＨＥＯＤＯＲＡ Ｗ．ＧＲＥＥＮＥ ａｎｄ ＰＥＴＥＲ Ｇ．Ｍ．ＷＵＴＳ著に詳細に記載されており、この文献の開示は本明細書に組み込まれる。
なお、上記製造法は式中の置換基に限定されるものではなく本発明化合物が同様の置換基を有する場合や反応基質と反応試剤が逆の場合にも広く適用される。
このようにして製造された本発明化合物は、遊離のまま、あるいはその塩として単離・精製される。
単離・精製は、抽出、濃縮、留去、結晶化、濾過、再結晶、各種クロマトグラフィー等の通常の化学操作を適用して行われる。
各種の異性体は、適当な原料化合物を選択することにより、あるいは異性体間の物理的性質の差を利用して分離することができる。例えば、光学異性体は、適当な原料を選択することにより、あるいはラセミ化合物のラセミ分割法（例えば、一般的な光学活性な塩基とのジアステレオマー塩に導き、光学分割する方法等）により立体化学的に純粋な異性体に導くことができる。
本発明化合物又はその塩の１種又は２種以上を有効成分として含有する製剤は、通常製剤化に用いられる担体や賦形剤、その他の添加剤を用いて調製される。
製剤用の担体や賦形剤としては、固体又は液体いずれでも良く、例えば乳糖、ステアリン酸マグネシウム、スターチ、タルク、ゼラチン、寒天、ペクチン、アラビアゴム、オリーブ油、ゴマ油、カカオバター、エチレングリコール等やその他常用のものが挙げられる。
投与は錠剤、丸剤、カプセル剤、顆粒剤、散剤、液剤等による経口投与、あるいは静注、筋注等の注射剤、坐剤、経皮等による非経口投与のいずれの形態であってもよい。投与量は症状、投与対象の年齢、性別等を考慮して個々の場合に応じて適宜決定されるが、通常成人１人当たり、１日につき１〜１，０００ｍｇ、好ましくは５０〜２００ｍｇの範囲で１日１回から数回に分け経口投与されるか又は成人１人当たり、１日につき１〜５００ｍｇの範囲で、１日１回から数回に分け静脈内投与されるか、又は、１日１時間〜２４時間の範囲で静脈内持続投与される。もちろん前記したように、投与量は種々の条件で変動するので、上記投与量範囲より少ない量で十分な場合もある。
本発明による経口投与のための固体組成物としては、錠剤、散剤、顆粒剤等が用いられる。このような固体組成物においては、一つまたはそれ以上の活性物質が、少なくとも一つの不活性な希釈剤、例えば乳糖、マンニトール、ブドウ糖、ヒドロキシプロピルセルロース、微結晶セルロース、デンプン、ポリビニルピロリドン、メタケイ酸アルミン酸マグネシウムと混合される。組成物は、常法に従って、不活性な希釈剤以外の添加剤、例えばステアリン酸マグネシウムのような潤滑剤や、デンプン、繊維素グルコール酸カルシウムのような崩壊剤、ラクトースのような安定化剤、グルタミン酸又はアスパラギン酸のような溶解補助剤を含有していてもよい。錠剤又は丸剤は必要によりショ糖、ゼラチン、ヒドロキシプロピルセルロース、ヒドロキシプロピルメチルセルロースフタレート等の糖衣又は胃溶性あるいは腸溶性物質のフィルムで被膜してもよい。
経口投与のための液体組成物は、薬剤的に許容される乳濁剤、溶液剤、懸濁剤、シロップ剤、エリキシル剤等を含み、一般的に用いられる不活性な希釈剤、例えば精製水、エタノールを含む。この組成物は不活性な希釈剤以外に湿潤剤、懸濁剤のような補助剤、甘味剤、風味剤、芳香剤、防腐剤を含有していてもよい。
非経口投与のための注射剤としては、無菌の水性又は非水性の溶液剤、懸濁剤、乳濁剤を包含する。水性の溶液剤、懸濁剤としては、例えば注射用蒸留水及び生理食塩水が含まれる。非水溶性の溶液剤、懸濁剤としては、例えばプロピレングリコール、ポリエチレングリコール、オリーブ油のような植物油、エタノールのようなアルコール類、ポリソルベート８０等がある。このような組成物はさらに防腐剤、湿潤剤、乳化剤、分散剤、安定化剤（例えば、ラクトース）、溶解補助剤（例えば、グルタミン酸、アスパラギン酸）のような補助剤を含んでいてもよい。これらは例えばバクテリア保留フィルターを通す濾過、殺菌剤の配合又は照射によって無菌化される。また、これらは無菌の固体組成物を製造し、使用前に無菌水又は無菌の注射用溶媒に溶解して使用することもできる。The compound of the present invention will be further described as follows.
In the definition of the general formula in the present specification, the term “lower” means a straight or branched carbon chain having 1 to 6 carbon atoms unless otherwise specified.
“Lower alkyl” is C _1-6 alkyl, preferably linear or branched C _1-4 alkyl such as methyl, ethyl, propyl, isopropyl, t-butyl, more preferably C _1-3 alkyl. It is.
“Lower alkylene” is C _1-6 alkylene, preferably linear or branched C _1-4 alkylene such as methylene, ethylene, methylmethylene, trimethylene, propylene, ethylethylene, tetrabutylene, more preferably C _1-3 alkylene.
The lower alkylene substituted with an oxo group means a group in which any carbon atom of the lower alkylene is substituted with an oxo group, preferably —CH ₂ —C (O) —, —C (O) —CH _{2 -, - CH 2 -C (} O) -CH 2 -, - (CH 2) 2 -C (O) -, - C (O) - (CH 2) 2 - it is.
The “lower alkenyl” is C _2-6 alkenyl, preferably linear or branched C _2-4 alkenyl such as vinyl, propenyl, butenyl, and more preferably C _2-3 alkenyl.
“Lower alkynyl” is C _2-6 alkynyl, preferably linear or branched C _2-4 alkynyl such as ethynyl, propynyl, butynyl, more preferably C _2-3 alkynyl.
“Halogen” means a halogen atom, for example, a fluorine, chlorine, bromine or iodine atom.
The “halogeno lower alkyl” means a group in which any one or more hydrogen atoms of the lower alkyl are substituted by the halogen atom, and trifluoromethyl is preferable.
“Cycloalkyl” means 3 to 8 membered cycloalkyl, preferably cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl and the like.
“Saturated heterocycle” means a 3- to 8-membered saturated heterocycle containing 1 to 4 heteroatoms selected from a nitrogen atom, an oxygen atom or a sulfur atom, and is pyrrolidine, piperidine, piperazine, homopiperazine, imidazolidine. , Morpholine, thiomorpholine, oxirane, oxetane, thietane, tetrahydrofuran, tetrahydropyran, [1,3] dioxolane, [1,4] dioxane, tetrahydrothiophene, [1,4] dithiane, hexahydroazepine, hexahydro-pyrrolo [2 , 1-c] [1,4] oxazine and the like.
The “oxygen-containing saturated heterocycle” means a saturated heterocycle that always contains an oxygen atom as a heteroatom in the above-mentioned saturated heterocycle. That is, it means a 3- to 8-membered saturated heterocycle which may contain 1 or 2 nitrogen atoms or 1 or 2 nitrogen atoms in addition to 1 to 3 oxygen atoms. A 4- to 6-membered saturated heterocyclic ring is preferable, and oxetane, tetrahydrofuran, 1,3-dioxolane, tetrahydropyran, and morpholine are more preferable.
The “sulfur-containing saturated heterocycle” means a saturated heterocycle that always contains a sulfur atom as a heteroatom in the above-mentioned saturated heterocycle. That is, it means a 3- to 8-membered saturated heterocyclic ring which may contain 1 or 2 nitrogen atoms or oxygen atoms in addition to 1 to 3 sulfur atoms. A 4- to 6-membered saturated heterocyclic ring is preferable, and thietane, 1,3-dithiolane, tetrahydrothiophene, thiazolidine, and thiomorpholine are more preferable.
An optionally substituted oxygen-containing saturated heterocycle, an optionally substituted sulfur-containing saturated heterocycle, and an optionally substituted cycloalkyl may have 1 to 3 substituents on any carbon atom or heteroatom on the ring. You may have.
The substituent means an ordinary substituent conventionally used in the art of the group to be substituted, and as the most preferable substituent, halogen, cyano, halogeno lower alkyl, lower alkyl, OH, lower alkyl-O—, Oxo, lower alkyl-C (O)-, carboxyl, lower alkyl-O-C (O)-, lower alkyl-O-lower alkyl-, nitro, amino optionally substituted with one or two lower alkyls Etc.
The compounds of the present invention may have optical isomers (optically active substances, diastereomers, etc.) depending on the type of group. In addition, the compounds of the present invention include compounds having an amide bond or a double bond, and there exist tautomers and geometric isomers. The present invention includes a separated or a mixture of these isomers.
The compounds of the present invention form salts with acids or bases. Salts with acids include inorganic acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, Examples include acid addition salts with organic acids such as fumaric acid, maleic acid, lactic acid, malic acid, citric acid, tartaric acid, carbonic acid, picric acid, methanesulfonic acid, ethanesulfonic acid, and glutamic acid.
Salts with bases include inorganic bases such as sodium, potassium, magnesium, calcium and aluminum, organic bases such as methylamine, ethylamine, meglumine and ethanolamine, and salts and basic salts such as lysine, arginine and ornithine. Is mentioned. Furthermore, the compound of the present invention can form hydrates, solvates with ethanol and the like and crystal polymorphs.
Furthermore, the compounds of the present invention include pharmacologically acceptable prodrugs. Groups that form pharmacologically acceptable prodrugs of the compounds of the present invention include those described in Prog. Med. 5: 2157-2161 (1985) and the group described in Hirokawa Shoten 1990, “Pharmaceutical Development”, Volume 7, Molecular Design, pages 163 to 198. Specifically, it is a group that can be converted into a primary amine of the present invention or a secondary amine, OH, COOH, etc. by hydrolysis, solvolysis or under physiological conditions, for example, a prodrug of an OH group As, for example, -OC (O) -optionally substituted lower alkylene-C (O) OR (R represents H or lower alkyl, the same shall apply hereinafter), -OC (O) -optionally substituted lower alkenylene. -C (O) OR, -OC (O) -optionally substituted aryl, -OC (O) -lower alkylene-O-lower alkylene-C (O) OR, -OC (O) -C (O) R, —OC (O) -lower alkyl optionally substituted, —OSO ₂ —lower alkylene optionally substituted —C (O) OR, —O-phthalidyl, 5-methyl-1,3-dioxolen-2 -On-4-yl-methyloxy and the like It is below.
Production Method The compound (I) of the present invention can be produced by the following production method.
In the present specification, abbreviations in the general production methods, reference examples, examples and tables have the following meanings.
DMF: dimethylformamide, DMSO: dimethyl sulfoxide, THF: tetrahydrofuran

Below, each manufacturing method is demonstrated.
Production Method 1: Production of 4-amino-5-bromo-2-fluoro-3-nitrobenzoic acid derivative

(Wherein R ⁸ represents hydrogen or lower alkyl, and R ⁹ represents Cl, Br, or I.)
Production method 1 is a method for producing a nitroaniline derivative from an aniline derivative.
Step 1 is halogenation of the benzene ring. That is, (II) is converted into an ammonium complex such as bromine, hydrogen bromide, or tetrabutylammonium tribromide in a solvent such as carbon tetrachloride, chloroform, methylene chloride, 1,4-dioxane, DMF, DMSO, methanol, acetic acid, N- (III) can be produced by reacting with a halogenating agent such as bromosuccinimide, chlorine, N-chlorosuccinimide and the like under ice-cooling and heating conditions.
Step 2 is acylation of an amino group. That is, (III) is heated at low temperature with an acylating agent such as acid halide, acid anhydride, or active ester in an inert solvent such as THF, chloroform, diethyl ether, DMF, or acetonitrile, or in an active solvent such as pyridine. (IV) can be manufactured by making it react on conditions.
Step 3 is nitration of the benzene ring. That is, (IV) is reacted in a solvent such as sulfuric acid and acetic acid, with a nitrating agent such as nitric acid, potassium nitrate, and acetyl nitrate, or with nitric acid as a solvent, from low temperature to room temperature, and further under warming conditions as necessary. (V) can be manufactured. Alternatively, in an inert solvent such as toluene, acetonitrile, THF, sulfolane, or the like, using a nitrating agent such as nitronium tetrafluoroborate, the reaction may be performed at a low temperature to a room temperature condition, and further, if necessary, under a heating condition ( V) can be produced.
Step 4 is a deacylation reaction by hydrolysis. That is, (VI) can be produced by subjecting (V) to a hydrolysis reaction under acidic conditions or alkaline conditions. For acidic conditions, use sulfuric acid, hydrochloric acid, acetic acid, etc. For alkaline conditions, use sodium hydroxide, potassium hydroxide, potassium carbonate, etc., solvent such as methanol, ethanol, THF, acetonitrile, water, etc. The reaction is carried out at room temperature to warming conditions with a mixed solvent thereof or without a solvent.
Production method 2: Production of 4-amino-2-fluoro-5-nitrobenzoic acid derivative

Production method 2 is a method for producing an aminobenzene derivative from a fluorobenzene derivative by an ipso reaction. That is, (VI-b) can be obtained by reacting (VII) with an amine-based donor such as ammonium chloride or ammonia in a solvent such as ethanol or isopropanol, DMF, DMSO, water or the like at room temperature. Can be manufactured.
Production method 3: Production of thioxobenzimidazole ring

Production method 2 is a method for producing a thioxobenzimidazole ring from a nitroaniline derivative.
Step 1 is a reduction reaction. That is, by subjecting (VI) to a catalytic reduction reaction using a metal catalyst such as palladium in an inert solvent such as methanol, ethanol or DMF in a hydrogen atmosphere or in the presence of a hydrogen donor such as ammonium formate (VIII) ) Can be manufactured. When R9 is hydrogen, it reacts with iron, stannous chloride, etc. under acidic conditions such as acetic acid, hydrochloric acid, ammonium chloride, or in water and a mixed solvent such as methanol, ethanol, THF, etc. (VIII) can also be produced by reacting under a heating condition from room temperature using a reducing agent such as sodium hydrosulfite.
Step 2 is a cyclization reaction of the thioxobenzimidazole ring. That is, by reacting (VIII) with carbon disulfide, 1,1′-thiocarbonyldiimidazole, thiocarbonate, etc. in the presence or absence of a base such as triethylamine in an inert solvent such as methanol, ethanol or DMF. (IX) can be manufactured.
Furthermore, when the catalytic reduction reaction is performed in step 1, step 2 can be continued.
Production method 4: Production of thiazolobenzimidazole ring

Production method 4 is a method for producing a thiazolobenzimidazole ring from a thioxobenzimidazole ring.
Step 1 is an alkylation reaction. That is, (IX) and an α-haloacetic acid derivative are mixed in an alcohol solvent such as ethanol or methanol, or in an inert solvent such as DMF, THF or acetonitrile, sodium methoxide, sodium ethoxide, sodium hydroxide, potassium hydroxide, (X) can be produced by reacting at room temperature to warming conditions in the presence or absence of a base such as sodium hydride, potassium carbonate or sodium hydrogen carbonate.
Step 2 is a cyclization reaction. That is, (X) and a formylating agent such as formic acid ester and formic acid anhydride are mixed in an alcohol solvent such as ethanol or methanol, or in an inert solvent such as DMF, THF or acetonitrile, sodium ethoxide, potassium ethoxide, hydroxylation. (XI) can be produced by reacting under a basic condition such as sodium, sodium hydride, pyridine, triethylamine and the like under a heating condition from room temperature. This (XI) may take the equilibrium state of Formula 1 in the solution state.

Step 3 is an isomerization reaction of a dihydrothiazolobenzimidazole ring. That is, (XI) is made into an equilibrium mixture shown in Formula 1 in a solution or suspension state, and then treated with acidic conditions such as hydrochloric acid, sulfuric acid, acetic acid, trifluoroacetic acid, etc. to precipitate (XII). it can.
Step 4 is a dehydration reaction from a dihydrothiazolobenzimidazole ring to a thiazolobenzimidazole ring. That is, (XIII) can be produced by reacting (XII) with an acid such as concentrated sulfuric acid, acetic acid, trifluoroacetic acid or the like at room temperature under heating conditions. Also, in an inert solvent such as toluene and benzene, in acidic conditions such as p-toluenesulfonic acid and camphorsulfonic acid, if necessary, in the presence of a dehydrating agent such as molecular sieves, or in a Dean-Stark dehydrator (XIII) can also be produced by reacting under room temperature to warming conditions under dehydration reaction conditions.
Production method 5: Reduction of carboxylic acid

Production method 5 is a method for producing an alcohol form by reduction of a normal carboxylic acid. That is, by deriving (XIII-a) into a reaction active form such as an acid halide, acid anhydride, or active ester, and reacting it with a borate such as sodium borohydride or tetrabutylammonium borohydride ( XIV) can be produced.
Production method 6: Hydrolysis of ester

Production method 6 is hydrolysis of an ester. That is, (XV) can be produced by hydrolyzing (XIV) under acidic conditions or alkaline conditions. For acidic conditions, use sulfuric acid, hydrochloric acid, acetic acid, etc. For alkaline conditions, use sodium hydroxide, potassium hydroxide, potassium carbonate, etc., solvent such as methanol, ethanol, THF, acetonitrile, water, etc. The reaction is carried out at room temperature to warming conditions with a mixed solvent thereof or without a solvent.
Production method 7: Amidation

Production method 7 is a normal amidation reaction of carboxylic acid. That is, (XV) in an inert solvent such as DMF, THF, 1,2-dichloroethane, chloroform, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide, diphenylphosphoryl triazide, 1,1 ′ (XVI) can be produced by activating with a condensing agent such as -carbonyl-1H-imidazole, 1-hydroxybenzotriazole, and reacting this active form with the corresponding amine. As the activation of the carboxylic acid, an acid chloride method using thionyl chloride or oxalyl chloride, an acid anhydride method, an active phosphate method using phosphorus oxychloride, or the like can be used.
Manufacturing method 8: Oxidation of alcohol

Production method 8 is an oxidation reaction of alcohol to aldehyde. That is, (XVII) can be produced by reacting (XVI) with a sulfur trioxide / pyridine complex under ice-cooling at room temperature using DMSO as a solvent. (XVII) can also be produced by a normal oxidation reaction such as SWERN oxidation, chromic acid oxidation, permanganic acid oxidation or the like.
Production method 9: Reductive amination

(XVII) to (I) are ordinary reductive amination reactions. That is, (XVII) is present in a solvent such as methylene chloride, 1,2-dichloroethane, chloroform, THF, methanol, ethanol, etc., if necessary, an acid catalyst such as acetic acid or hydrochloric acid, or a Lewis acid such as titanium tetraisopropoxide. (I) can be produced by reacting the corresponding amine with a reducing agent such as sodium triacetoxyborohydride, sodium cyanoborohydride, sodium borohydride and the like. (I) (XVII) and the corresponding amine from an inert solvent such as toluene or benzene, if necessary under a dehydrating agent such as molecular sieves, or under dehydration reaction conditions using a Dean-Stark dehydrator It can also be produced by reacting under heating conditions to give an imine, which is treated with a reducing agent such as sodium borohydride in a solvent such as methanol or ethanol, or in a mixed solvent with the reaction solvent. Further, (I) can also be produced by using a metal catalyst such as palladium under normal catalytic reduction conditions, specifically, in a hydrogen atmosphere instead of using the reducing agent.
For general protecting groups such as a hydroxyl group, an amino group and an ester group, see PROTECTIVE GROUPS IN ORGANIC SYNTHESIS, THEODORA W., et al. GREEN and PETER G. M.M. It is described in detail by WUTS, the disclosure of which is incorporated herein.
In addition, the said manufacturing method is not limited to the substituent in a formula, and when this invention compound has a similar substituent, or when a reaction substrate and a reaction reagent are reverse, it is applied widely.
The compound of the present invention thus produced is isolated and purified as it is or as a salt thereof.
Isolation / purification is performed by applying ordinary chemical operations such as extraction, concentration, distillation, crystallization, filtration, recrystallization, and various chromatography.
Various isomers can be separated by selecting an appropriate raw material compound or utilizing the difference in physical properties between isomers. For example, optical isomers can be stereoisomerized by selecting appropriate raw materials or by racemic resolution of racemates (for example, diastereomeric salts with general optically active bases and optical resolution). Can lead to chemically pure isomers.
A preparation containing one or more of the compounds of the present invention or a salt thereof as an active ingredient is prepared using carriers, excipients, and other additives that are usually used for formulation.
The carrier or excipient for the preparation may be either solid or liquid, such as lactose, magnesium stearate, starch, talc, gelatin, agar, pectin, gum arabic, olive oil, sesame oil, cocoa butter, ethylene glycol, etc. The usual thing is mentioned.
Administration may be in any form of oral administration such as tablets, pills, capsules, granules, powders, liquids, or parenteral administration such as injections such as intravenous injection and intramuscular injection, suppositories, and transdermal. Good. The dose is appropriately determined depending on the individual case in consideration of symptoms, age of the administration subject, sex, etc., but is usually in the range of 1 to 1,000 mg, preferably 50 to 200 mg per day per adult. Orally administered in one to several divided doses per day, or in the range of 1 to 500 mg per adult per day, or administered intravenously in one to several divided doses per day, or 1 daily Intravenous continuous administration in the range of 24 hours. Of course, as described above, since the dose varies depending on various conditions, an amount smaller than the above dose range may be sufficient.
As the solid composition for oral administration according to the present invention, tablets, powders, granules and the like are used. In such solid compositions, one or more active substances are present in at least one inert diluent such as lactose, mannitol, glucose, hydroxypropylcellulose, microcrystalline cellulose, starch, polyvinylpyrrolidone, metasilicic acid. Mixed with magnesium aluminate. The composition is prepared according to conventional methods with additives other than inert diluents such as lubricants such as magnesium stearate, disintegrants such as starch and calcium calcium glycolate, stabilizers such as lactose, It may contain a solubilizing agent such as glutamic acid or aspartic acid. If necessary, tablets or pills may be coated with a sugar coating such as sucrose, gelatin, hydroxypropylcellulose, hydroxypropylmethylcellulose phthalate or the like, or a film of a gastric or enteric substance.
Liquid compositions for oral administration include pharmaceutically acceptable emulsions, solutions, suspensions, syrups, elixirs, etc., and commonly used inert diluents such as purified water. Contains ethanol. In addition to the inert diluent, the composition may contain adjuvants such as wetting agents and suspending agents, sweeteners, flavors, fragrances and preservatives.
Injections for parenteral administration include sterile aqueous or non-aqueous solutions, suspensions, and emulsions. Examples of the aqueous solution and suspension include distilled water for injection and physiological saline. Examples of water-insoluble solutions and suspensions include propylene glycol, polyethylene glycol, vegetable oils such as olive oil, alcohols such as ethanol, polysorbate 80, and the like. Such compositions may further contain adjuvants such as preservatives, wetting agents, emulsifiers, dispersants, stabilizers (eg lactose), solubilizers (eg glutamic acid, aspartic acid). These are sterilized by, for example, filtration through a bacteria-retaining filter, blending with a bactericide or irradiation. These can also be used by producing a sterile solid composition and dissolving it in sterile water or a sterile solvent for injection before use.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. In addition, the manufacturing method of the raw material compound used in an Example is demonstrated as a reference example. (The abbreviations used below have the following meanings.)
¹ H-NMR; ¹ H-nuclear magnetic resonance spectrum (heavy dimethyl sulfoxide (hereinafter DMSO-d ₆ ), deuterated chloroform (hereinafter CDCl 3) or deuterated methanol (hereinafter CD 3 OD) was used as a measurement solvent, tetramethylsilane as an internal standard Measured at 300 MHz or 400 MHz, chemical shifts are given in ppm.br:broad, s; singlet, d; doublelet, t; triplet, q; quartet, m;
MS; mass spectrometry (FAB +: positive ion fast atom bombardment mass spectrometry, FAB-: negative ion fast atom bombardment mass spectrometry, ES +: positive ion electrospray ionization method, ES-: negative ion electrospray ionization method. M: molecular weight )
Ex: Example number Column chromatography used for purification used silica gel as the packing material.
Reference example 1
Ethyl 4 -amino-5-bromo-2-fluorobenzoate To a solution of ethyl 4-amino-2-fluorobenzoate (10.0 g) in chloroform (200 ml) was added tetrabutylammonium tribromide (27.7 g) under ice-cooling. A chloroform (60 ml) solution was added dropwise over 50 minutes. After completion, the reaction solution was concentrated under reduced pressure, and the residue was extracted with ethyl acetate. The organic layer was washed successively with 10% aqueous citric acid solution, saturated aqueous sodium hydrogen carbonate solution and saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crystallized residue was recrystallized from hexane (50 ml) and ethyl acetate (10 ml), collected by filtration, and washed with a mixed solvent of hexane and ethyl acetate (mixing ratio 10: 1). The obtained crystals were dried under reduced pressure at 50 ° C. to give the titled compound (10.1 g).
¹ H-NMR (DMSO-d ₆ ); 1.27 (t, 3H), 4.23 (q, 2H), 6.43 (br, 2H), 6.55 (d, 1H), 7.82 (D, 1H)
Reference example 2
Ethyl 4- (acetylamino) -5-bromo-2-fluorobenzoate To a solution of the compound of Reference Example 1 (128.27 g) in THF (800 ml) was added acetyl chloride (104.4 ml) under ice-cooling, and the whole room at night and day. Stir. After completion, the reaction solution was concentrated under reduced pressure and extracted with ethyl acetate. The organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. Ethyl acetate (200 ml) was added to the crystallized residue, dissolved by heating under reflux, and then hexane (250 ml) was added for crystallization. The precipitated crystals were collected by filtration and washed with a mixed solvent of hexane and ethyl acetate (mixing ratio 3: 1). The obtained crystals were dried under reduced pressure while heating at 50 ° C. to give the titled compound (140.5 g).
¹ H-NMR (DMSO-d ₆ ); 1.31 (t, 3H), 2.18 (s, 3H), 4.31 (q, 2H), 7.92 (d, 1H), 8.07 (D, 1H), 9.57 (br, 1H)
Reference example 3
A solution of ethyl 4- (acetylamino) -5-bromo-2-fluoro-3-nitrobenzoate Reference Example 2 (125.5 g) in concentrated sulfuric acid (800 ml) was cooled in a sodium chloride-ice water bath and mechanically cooled. While stirring with a stirrer, fuming nitric acid (342 ml) was added dropwise over 2 hours. After completion of dropping, the mixture was stirred in a sodium chloride-ice water bath for 6 and a half hours. After completion, the reaction solution was poured into ice water (8 L) and stirred at 5 ° C. for 1 day. After stirring, the insoluble material was collected by filtration, washed with water, and dissolved using THF and ethyl acetate. The solution was dried over anhydrous sodium sulfate and concentrated under reduced pressure. Ethyl acetate (400 ml) was added to the residue, heated to reflux for dissolution, and then hexane (400 ml) was added for crystallization. The precipitated crystals were collected by filtration and washed with a mixed solvent of hexane and ethyl acetate (mixing ratio 3: 1). The obtained crystals were dried under reduced pressure while heating at 50 ° C. to give the titled compound (70.6 g).
¹ H-NMR (DMSO-d ₆ ); 1.33 (t, 3H), 2.08 (s, 3H), 4.36 (q, 2H), 8.38 (d, 1H), 10.50 (Br, 1H)
Reference example 4
4-amino-5-bromo-2-fluoro-3-nitrobenzoic acid The compound of Reference Example 3 (88.4 g) was dissolved in a mixed solvent of concentrated hydrochloric acid and acetic acid (mixing ratio 1: 1, 1 L). The mixture was stirred in an oil bath at 100 ° C. all day and night. After completion, the reaction solution was ice-cooled and poured into ice water (4 L). The precipitated crystals were collected by filtration, washed with water, and dried under reduced pressure while heating at 70 ° C. to give the titled compound (65.2 g).
¹ H-NMR (DMSO-d ₆ ); 7.14 (br, 2H), 8.04 (d, 1H), 13.24 (br, 1H)
Reference Example 5
4-Fluoro-2-thioxo-2,3-dihydro-1H-benzimidazole-5- carboxylic acid To a solution of the compound of Reference Example 4 (16.7 g) in methanol (300 ml) in 10% palladium-carbon (1 .67 g) was added, and the mixture was stirred at room temperature for 3 hours under a hydrogen atmosphere. After completion, carbon disulfide (4.69 ml) and triethylamine (8.35 ml) were added and stirred in an oil bath at 30 ° C. for 14 hours. Further, carbon disulfide (6.13 ml) and triethylamine (8.35 ml) were added, and the mixture was stirred in an oil bath at 40 ° C. for 9 and a half hours. After completion, the reaction solution was filtered and then concentrated under reduced pressure. A 1M aqueous hydrochloric acid solution (200 ml) was added to the residue, and the precipitated crystals were collected by filtration. The crystals were washed with 1M aqueous hydrochloric acid solution and water, and dried under reduced pressure while heating at 60 ° C. to give the titled compound (11.9 g).
¹ H-NMR (DMSO-d ₆ ); 7.02 (d, 2H), 7.66 (dd, 1H), 12.99 (br, 1H), 13.30 (br, 1H)
Reference Example 6
2 - [(2-ethoxy -2-oxoethyl) sulfanyl]-4-DMF (60 ml) solution of fluoro -1H- base emission zone imidazole 5-carboxylic acid hydrobromide compound of Reference Example 5 (14.7 g) To the mixture, ethyl bromoacetate (11.6 ml) was added and stirred in an oil bath at 60 ° C. for 1 hour. After completion, the reaction solution was concentrated under reduced pressure, and 2-butanone (200 ml) was added. The precipitated crystals were collected by filtration, washed with 2-butanone, and then dried under reduced pressure while heating at 60 ° C. to obtain the title compound (21.5 g).
¹ H-NMR (DMSO-d ₆ ); 1.19 (t, 3H), 4.14 (q, 2H), 4.26 (s, 2H), 7.30 (d, 1H), 7.63 -7.67 (m, 1H)
Reference Example 7
2- (ethoxycarbonyl) -8-fluoro-3-hydroxy-2,3-Jihidorochi Asolo [3,2-a] - DMF compounds benzimidazole-7-carboxylic acid Reference Example 6 (21.5 g) (160 ml ) Ethyl formate (45.6 ml) was added to the solution in an ice-cooled atmosphere under an argon atmosphere, and a 20% sodium ethoxide / ethanol solution (111 ml) was further added dropwise over 30 minutes. After completion of dropping, the mixture was stirred in a 40 ° C. hot water bath for 2.5 hours. After completion, 1M hydrochloric acid (227 ml) was added to the reaction mixture and concentrated under reduced pressure. Water (200 ml) was added to the residue, and the precipitated crystals were collected by filtration. The collected crystals were washed with water and then dried under reduced pressure while heating at 60 ° C. to give the title compound (16.9 g).
MS (ES-); 325 (M-1)
Reference Example 8
2- (ethoxycarbonyl) -5-fluoro-3-hydroxy-2,3-Jihidorochi Asolo [3,2-a] benzimidazole-6-carboxylic acid hydrochloride compound of Reference Example 7 (16.3 g) ethanol ( (100 ml) A 4N hydrochloric acid / ethyl acetate solution (25.0 ml) was added to the suspension under ice cooling. The reaction suspension was heated and dissolved, ethyl acetate (400 ml) was added, and the mixture was stirred at 5 ° C. overnight. After completion, the precipitated crystals were collected by filtration, washed with ethyl acetate, and dried under reduced pressure while heating at 60 ° C. to give the title compound (15.5 g).
MS (ES-); 325 (M-1)
Reference Example 9
2- (ethoxycarbonyl) -5-fluoro-thiazolo [3.2-a] benzo imidazole-6-carboxylic acid compound of the sulfate in Reference Example 8 (15.5 g) was dissolved in concentrated sulfuric acid (50 ml), The mixture was stirred for 4 hours in an oil bath at 45 ° C. After completion, the reaction solution was ice-cooled and then dispersed in ice-cooled ethyl acetate (400 ml). The precipitated crystals were collected by filtration, washed with ethyl acetate, and dried under reduced pressure while heating at 60 ° C. to give the title compound (14.5 g).
¹ H-NMR (DMSO-d ₆ ); 1.37 (t, 3H), 4.39 (q, 2H), 7.59 (d, 1H), 7.87-7.89 (m, 1H)
Reference Example 10
5-fluoro-6- (hydroxymethyl) thiazolo [3,2-a] benzo imidazole-2-carboxylate The compound of Reference Example 9 (14.5 g) was suspended in acetonitrile (150 ml), under an argon atmosphere at room temperature Medium 1,1′-carboxydiimidazole (17.4 g) was added. After the addition, the reaction mixture was stirred at room temperature for 3 hours. Subsequently, the reaction mixture was ice-cooled, sodium borohydride (4.05 g) /0.1% aqueous sodium hydroxide solution (20 ml) was added, and the mixture was stirred for 5 hours while cooling with ice, and further stirred for 4 hours after warming to room temperature. did. After completion, concentrated hydrochloric acid (25.3 g) and water (230 ml) were added to the reaction suspension, and the mixture was heated to reflux for 30 minutes. The reaction suspension was ice-cooled, and the precipitated crystals were collected by filtration. The precipitate was washed with water and dried under reduced pressure at 60 ° C. to give the title compound (7.97 g).
¹ H-NMR (DMSO-d ₆ ); 1.32-1.37 (m, 3H), 4.38 (q, 2H), 4.69 (s, 2H), 5.35 (br, 1H) , 7.44-7.48 (m, 1H), 7.53 (d, 1H), 8.79 (s, 1H)
Reference Example 11
5-fluoro-6 was suspended in (hydroxymethyl) thiazolo [3,2-a] benzo imidazole-2-compound of the carboxylic acid Reference Example 10 (7.95 g) of 40% aqueous acetonitrile (100 ml), ice The solution was added to a 1M aqueous sodium hydroxide solution (32 ml) and stirred at room temperature for 4 hours. After completion, 1M aqueous hydrochloric acid solution (32 ml) was added to the reaction solution, and the mixture was cooled with ice. The precipitated crystals were collected by filtration. The filtered product was washed with water and dried under reduced pressure at 60 ° C. to give the title compound (6.49 g).
¹ H-NMR (DMSO-d ₆ ); 4.69 (s, 2H), 5.34 (br, 1H), 7.42-7.46 (m, 1H), 7.50-7.52 ( m, 1H), 8.66 (s, 1H)
Reference Example 12
5-Fluoro-6- (hydroxymethyl) -N-methyl-N-neopentylthiazolo [3,2-a] benzimidazole-2-carboxamide DMF (350 ml) suspended from the compound of Reference Example 11 (20.8 g) Methyl neopentylamine hydrochloride (21.5 g), triethylamine (21.7 ml), 1-hydroxybenzotriazole (13.7 g) and 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride in room temperature at room temperature Salt (29.9 g) was added and the reaction mixture was stirred overnight at room temperature. After completion, the reaction mixture was poured into 0.5 M aqueous sodium hydroxide solution (3 L) under ice cooling and stirred for 2 hours under ice cooling. The insoluble material was collected by filtration, washed with water, and dried under reduced pressure at 70 ° C. to give the title compound (23.3 g).
¹ H-NMR (DMSO-d ₆ ); 0.97 (s, 9H), 3.40-3.46 (m, 5H), 4.69-4.70 (m, 2H), 5.31 ( t, 1H), 7.41-7.45 (m, 1H), 7.50-7.52 (m, 1H), 8.64 (s, 1H)
Reference Example 13
5-Fluoro-6-formyl-N-methyl-N- neopentylthiazolo [3,2-a] benzimidazole-2-carboxamide A solution of the compound of Reference Example 12 (6.92 g) in DMSO (100 ml) at room temperature. Triethylamine (11.0 ml) and sulfur trioxide / pyridine mixture (15.76 g) were added slowly and the reaction mixture was stirred at room temperature for 20 minutes. After completion, the reaction mixture was added to 0.17 M aqueous sodium hydroxide solution (1.2 L) under ice cooling and stirred for 15 minutes. The reaction solution was extracted with chloroform, and the organic layer was washed with water and saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crystallized residue was recrystallized with ethanol and ethyl acetate, and the resulting crystals were collected by filtration. The crystals were washed with a mixed solvent of ethanol and ethyl acetate (mixing ratio 1: 3) and then dried under reduced pressure at 60 ° C. to give the title compound (3.65 g). Further, the recrystallization mother liquor and washing solution were concentrated under reduced pressure, and the residue was subjected to column chromatography (eluent; hexane, hexane: ethyl acetate = 10: 1, hexane: ethyl acetate = 3: 2, then hexane: ethyl acetate = 2: 3). ) To give the title compound (1.90 g).
¹ H-NMR (DMSO-d ₆ ); 0.98 (s, 9H), 3.41-3.48 (m, 5H), 7.65-7.67 (m, 1H), 7.80- 7.84 (m, 1H), 8.80 (s, 1H), 10.33 (s, 1H)
Reference Example 14
4-Amino-2-fluoro-5-nitrobenzoic acid ammonium salt 2,4-difluoro-5-nitrobenzoic acid (26.29 g) was dissolved in concentrated aqueous ammonia (500 ml) and the reaction mixture was stirred at room temperature for 4 hours. did. After completion, the mixture was concentrated under reduced pressure. Ethanol was added to the residue and the mixture was concentrated again under reduced pressure. The residue was washed with water and a small amount of ethanol and dried under reduced pressure to give the title compound (26.38 g).
¹ H-NMR (DMSO-d ₆ ); 6.65 (d, 1H), 7.62 (s, 2H), 8.47 (d, 1H)
Reference Example 15
6-Fluoro-2-thioxo-2,3-dihydro-1H-benzimidazole-5- carboxylic acid To a solution of the compound of Reference Example 14 (4.38 g) in methanol (100 ml) was added 6M aqueous hydrochloric acid (10 ml) and aqueous palladium / Carbon (0.44 g) was added and the mixture was stirred for 4 hours at room temperature under atmospheric hydrogen atmosphere. To the mixture was added triethylamine (11.1 ml) and carbon disulfide (2.4 ml), which was stirred at room temperature for 3 days. The insoluble material was filtered off, washed with methanol, and the filtrate was concentrated. The residue was suspended in water, and the mixture was adjusted to acidic with 1M aqueous hydrochloric acid. The insoluble material was collected by filtration, washed with water, and suspended in methanol. The mixture was concentrated under reduced pressure to give the title compound (3.40 g).
¹ H-NMR (DMSO-d ₆ ); 7.02 (d, 1H), 7.54 (d, 1H), 12.78 (s, 1H), 12.88 (s, 1H), 13.06 (Br, 1H)
Reference Example 16
2-[(2-Ethoxy-2-oxoethyl) sulfanyl] -6-fluoro-1H- benzimidazole-5-carboxylic acid Hydrobromide To a DMF (100 ml) solution of the compound of Reference Example 15 (10.65 g) Ethyl bromoacetate (6.68 ml) was added and the mixture was stirred at room temperature for 2 hours. After completion, the mixture was concentrated to an appropriate amount under reduced pressure. The residue was diluted with 2-butanone. The precipitate was collected by filtration, washed with 2-butanone and dried under reduced pressure to obtain the title compound (17.08 g).
¹ H-NMR (DMSO-d ₆ ); 1.18 (t, 3H), 4.13 (q, 2H), 4.26 (s, 1H), 7.37 (d, 1H), 7.90 (D, 1H), 7.96 (s, 1H)
Reference Example 17
2- (ethoxycarbonyl) -7-fluoro-thiazolo [3,2-a] in benz imidazole-6-carboxylic acid sulfate ice bath, DMF (150 ml) solution of the compound of Reference Example 16 (16.90 g) To the mixture was added ethyl formate (35.88 ml). A 20% sodium ethoxide ethanol solution (87.36 ml) was added to the mixture at 5 ° C. or lower, and this was stirred in an oil bath at 50 ° C. for 2 hours. After completion, 1M aqueous hydrochloric acid solution (178.28 ml) was added to the mixture in an ice bath at 10 ° C. or lower, and the mixture was concentrated under reduced pressure. Water was added to the residue, insoluble matter was collected by filtration, washed with water and dried under reduced pressure to give 6-fluoro-3-hydroxy-2,3-dihydrothiazolo [3,2-a] benzimidazole-2, 7-dicarboxylic acid (12.49 g, MS (ES +): 327 (M + 1)) was obtained. In an ice bath, 4M was added to a suspension of 6-fluoro-3-hydroxy-2,3-dihydrothiazolo [3,2-a] benzimidazole-2,7-dicarboxylic acid (12.40 g) in ethanol (62 ml). After adding a hydrochloric acid / ethyl acetate solution (19 ml), the ice bath was removed and the mixture was stirred to change from a suspension to a solution. Ethyl acetate (155 ml) was added thereto, and the mixture was stirred at 5 ° C. overnight. The precipitate was collected by filtration, washed with ethyl acetate and then dried under reduced pressure to give 2- (ethoxycarbonyl) -7-fluoro-3-hydroxy-2,3-dihydrothiazolo [3,2-a] benzimidazole- 6-carboxylic acid hydrochloride (10.12 g) was obtained. Next, a concentrated sulfuric acid (30 ml) solution of 2- (ethoxycarbonyl) -7-fluoro-3-hydroxy-2,3-dihydrothiazolo [3,2-a] benzimidazole-6-carboxylic acid (9.98 g) was added. The mixture was stirred for 3 hours in an oil bath at 30 ° C. After completion, the mixture was poured into cold ethyl acetate (500 ml). The precipitate was collected by filtration, washed with ethyl acetate and dried under reduced pressure to give the title compound (9.96 g).
¹ H-NMR (80 ° C., DMSO-d ₆ + CD3OD); 1.36 (t, 3H), 4.39 (q, 2H), 7.54 (d, 1H), 8.76 (d, 1H) , 9.38 (s, 1H)
Reference Example 18
7-fluoro-6- (hydroxymethyl) thiazolo [3,2-a] acetonitrile (120 ml) suspension of benz imidazole-2-carboxylate The compound of Reference Example 17 (11.84 g) 1,1' Carboxydiimidazole (14.16 g) was added and the mixture was stirred at room temperature for 6 hours. To the mixture was added sodium borohydride (3.30 g) in 0.1% aqueous sodium hydroxide solution (18 ml) in an ice bath at 10 ° C. or lower, and the mixture was stirred at 5 ° C. overnight. Concentrated hydrochloric acid (17.5 ml) and water (200 ml) were added to the mixture, and the mixture was heated to reflux for 2 hours. After completion, the reaction mixture was stirred in an ice bath for 2 hours. The insoluble material was collected by filtration, washed with water and acetonitrile, and dried under reduced pressure to give the title compound (6.52 g).
¹ H-NMR (DMSO-d ₆ ); 1.35 (t, 3H), 4.37 (q, 2H), 4.68 (d, 2H), 5.41 (t, 1H), 7.51 (D, 1H), 8.27 (d, 1H), 9.45 (s, 1H)
Reference Example 19
7-fluoro-6- (hydroxymethyl) thiazolo [3,2-a] benzimidazole imidazole-2-carboxylic acid compound of Reference Example 18 in acetonitrile (6.40 g) (50 ml) suspension in water (30ml) and 1M Aqueous sodium hydroxide (26.1 ml) was added and the mixture was stirred at room temperature for 6 hours. After completion, 1M aqueous hydrochloric acid (26.1 ml) was added to the reaction mixture and the mixture was stirred at room temperature for 30 minutes. The insoluble material was collected by filtration, washed with water and acetonitrile, and dried under reduced pressure to give the title compound (5.69 g).
¹ H-NMR (DMSO-d ₆ ); 4.68 (s, 2H), 5.41 (br, 1H), 7.49 (d, 1H), 8.24 (d, 1H), 9.30 (S, 1H)
Reference Example 20
7-Fluoro-6- (hydroxymethyl) -N-methyl-N- neopentylthiazolo [3,2-a] benzimidazole-2-carboxamide Reference Example 19 compound (5.22 g) in DMF (90 ml) Methyl neopentylamine hydrochloride (5.70 g), triethylamine (5.77 ml), 1-hydroxybenzotriazole (5.59 g) and 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride ( 7.94 g) was added and the mixture was stirred at room temperature overnight. After completion, 1M aqueous sodium hydroxide solution (100 ml) was added to the reaction mixture, and the mixture was stirred at room temperature for 1 hour. The insoluble material was collected by filtration and washed with water. The filtrate was extracted with ethyl acetate, and the organic layer was washed with water and concentrated under reduced pressure. The residue and the filtered product obtained earlier were combined and suspended in ethanol, and the mixture was concentrated under reduced pressure to obtain the title compound (6.78 g).
¹ H-NMR (DMSO-d ₆ ); 0.96 (s, 9H), 3.41 (br, 2H), 3.46 (br, 3H), 4.70 (d, 2H), 5.44 (T, 1H), 7.47 (d, 1H), 8.22 (d, 1H), 9.13 (s, 1H)
Reference Example 21
7-Fluoro-6-formyl-N-methyl-N-neopentylthiazolo [3,2-a] benzimidazole-2-carboxamide In a solution of the compound of Reference Example 20 (6.75 g) in DMSO (100 ml), triethylamine ( 10.76 ml) and sulfur trioxide / pyridine mixture (15.36 g) were added and the mixture was stirred at room temperature for 1 hour. After completion, the mixture was poured into water and adjusted to alkaline with 1M aqueous sodium hydroxide solution. The precipitate was collected by filtration, washed with water, and dried under reduced pressure. The obtained compound was roughly purified by column chromatography (eluent: chloroform: methanol = 90: 10). The obtained crude product was recrystallized from THF and ethyl acetate and washed with ethyl acetate to obtain the title compound (2.82 g).
¹ H-NMR (DMSO-d ₆ ); 0.97 (s, 9H), 3.42 (br, 2H), 3.47 (br, 3H), 7.68 (d, 1H), 8.66 (D, 1H), 9.24 (s, 1H), 10.32 (s, 1H)
Reference Example 22
Acetic anhydride (81.4 ml) was added to a solution of ethyl 4- (acetylamino) -3-fluorobenzoate in ethyl 4-amino-3-fluorobenzoate (31.88 g) in pyridine (300 ml), and the mixture was stirred for 72 hours. did. Water (30 ml) was added thereto, and the mixture was further stirred at room temperature for 30 minutes. After completion, the mixture was concentrated under reduced pressure. The residue was partitioned between ethyl acetate and water. The aqueous layer was separated and extracted with ethyl acetate. The collected organic layer was washed with 10% aqueous citric acid solution, saturated aqueous sodium hydrogen carbonate solution, water and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was recrystallized from ethyl acetate and hexane to obtain the title compound (30.24 g).
¹ H-NMR (DMSO-d ₆ ); 1.32 (t, 3H), 2.15 (s, 3H), 4.30 (q, 2H), 7.71-7.77 (m, 2H) , 8.21-8.25 (m, 1H), 10.01 (s, 1H)
Reference Example 23
In a solution of ethyl 4- (acetylamino) -3-fluoro-5-nitrobenzoate in an ice / saline bath, fuming nitric acid (12.4 ml) was added to a concentrated sulfuric acid (70 ml) solution of the compound of Reference Example 22 (6.76 g). The solution was gradually added dropwise so that the temperature did not exceed 0 ° C. After completion of dropping, the mixture was further stirred in an ice / brine bath for 2 hours. After completion, the mixture was poured into ice water. The precipitate was collected by filtration, washed with ice water, and then dried under reduced pressure with heating to obtain the title compound (5.84 g).
¹ H-NMR (DMSO-d ₆ ); 1.34 (t, 3H), 2.11 (s, 3H), 4.37 (q, 2H), 8.14 (dd, 1H), 8.21 (T, 1H), 10.63 (s, 1H)
Reference Example 24
4-Amino-3-fluoro-5-nitrobenzoic acid To a solution of the compound of Reference Example 23 (9.90 g) in ethanol (200 ml) was added 1M aqueous sodium hydroxide solution (110 ml), and this was added overnight in an oil bath at 80 ° C. Stir. The mixture was cooled to room temperature, and 1M aqueous hydrochloric acid solution (110 ml) was added thereto. The precipitate was collected by filtration, washed with cold water, and dried under reduced pressure with heating to obtain the title compound (4.87 g).
¹ H-NMR (DMSO-d ₆ ); 7.77 (dd, 1H), 7.86 (s, 2H), 8.41 (t, 1H), 13.09 (s, 1H)
Reference Example 25
7-Fluoro-2-thioxo-2,3-dihydro-1H-benzimidazole-5- carboxylic acid To a solution of the compound of Reference Example 24 (4.83 g) in methanol (100 ml) was added hydrous palladium / carbon (241 mg), The mixture was stirred at room temperature for 3 hours under atmospheric hydrogen atmosphere. Carbon disulfide (2.18 ml) was added to the mixture and the mixture was stirred in a 60 ° C. oil bath overnight. The mixture was filtered and washed with methanol, then the filtrate was concentrated. Carbon disulfide (4.36 ml) was added to a solution of the residue in methanol (30 ml), and the mixture was stirred overnight in a 40 ° C. oil bath. Triethylamine (3.36 ml) was added to the mixture, and the mixture was further stirred in a 40 ° C. oil bath for 1 hour. After completion, the reaction mixture was concentrated under reduced pressure. The residue was diluted with water and then acidified with 1M aqueous hydrochloric acid. The precipitate was collected by filtration, washed with water and dried under reduced pressure to give the title compound (4.93 g).
¹ H-NMR (DMSO-d ₆ ); 7.53 (s, 1H), 7.53 (d, 1H), 13.02 (s, 1H), 13.13 (br, 1H), 13.41 (S, 1H)

5-Fluoro -N- methyl -N- neopentyl-6 - [(oxetan-3 Iruami Roh) methyl] [1,3] thiazolo [3,2-a] benzimidazol-2-carboxy Samido 1 fumarate Reference Acetic acid (206 μl), 3-aminooxetane hydrochloride (267 mg), and triethylamine (301 μl) were added to a dichloroethane solution (15 ml) of the compound of Example 12 (250 mg), and the mixture was stirred at room temperature for 2 hours. Subsequently, sodium triacetoxyborohydride (458 mg) was added, and the mixture was stirred at room temperature for 14 hours. Further, sodium triacetoxyborohydride (458 mg) was added, and the mixture was stirred at room temperature for 4 and a half hours. After completion, 1M aqueous sodium hydroxide solution was added to the reaction solution, extracted with 5% methanol / chloroform solution, and concentrated under reduced pressure. The residue was subjected to column chromatography (eluent; ethyl acetate and then ethyl acetate: methanol = 40: 1, then ethyl acetate: methanol: 28% aqueous ammonia = 40: 1: 0.1, then ethyl acetate: methanol: 28% aqueous ammonia = 20: 1: 0.1, and then purified by ethyl acetate: methanol: 28% aqueous ammonia = 10: 1: 0.1). Ethanol was added to the purified product and dissolved, fumaric acid (141 mg) was added, and the mixture was concentrated under reduced pressure. The crystallized residue was recrystallized from ethanol and ethyl acetate, and the resulting crystals were collected by filtration. The crystals collected by filtration were dried under reduced pressure to give the title compound (279 mg).
¹ H-NMR (DMSO-d ₆ ); 0.97 (s, 9H), 3.40-3.46 (m, 5H), 3.87 (s, 2H), 3.91-3.98 ( m, 1H), 4.33-4.37 (m, 2H), 4.55-4.58 (m, 2H), 6.62 (s, 2H), 7.41 (dd, 1H), 7 .50 (d, 1H), 8.65 (s, 1H)
MS (EAB +); 405 (M + 1)

6 - {[(1,3-dioxolan-2-ylmethyl) amino] methyl} -5-fluoro -N- methyl -N- neopentyl [1,3] thiazolo [3-2-a] benzo imidazole -2 - compound carboxamide monohydrochloride reference example 12 (150 mg) acetic acid (123Myueru) in dichloroethane (10ml) of (1,3-dioxolan-2-yl) added methylamine (122Myueru), 2 hours stirring at room temperature did. Subsequently, sodium triacetoxyborohydride (274 mg) was added and stirred at room temperature for 14 hours. Further, sodium triacetoxyborohydride (274 mg) was added, and the mixture was stirred at room temperature for 4 and a half hours. After completion, 1M aqueous sodium hydroxide solution was added to the reaction solution, extracted with 5% methanol / chloroform solution, and concentrated under reduced pressure. The residue was subjected to column chromatography (eluent; ethyl acetate then ethyl acetate: methanol = 20: 1, then ethyl acetate: methanol: 28% aqueous ammonia = 20: 1: 0.1, then ethyl acetate: methanol: 28% aqueous ammonia = 10: 1: 0.1). Ethanol (10 ml) was added and dissolved in the purified product, 1M aqueous hydrochloric acid solution (0.76 ml) was added, and the mixture was concentrated under reduced pressure. The crystallized residue was recrystallized from ethanol and ethyl acetate, and the resulting crystals were collected by filtration. The crystals collected by filtration were washed with a mixed solvent of ethanol and ethyl acetate (mixing ratio 1: 5), and then dried under reduced pressure while heating at 60 ° C. to obtain the title compound (142 mg).
¹ H-NMR (DMSO-d ₆ ); 0.97 (s, 9H), 3.17 (d, 2H), 3.41-3.46 (m, 5H), 3.85-3.93 ( m, 2H), 3.97-4.06 (m, 2H), 4.40 (s, 2H), 5.23 (t, 1H), 7.61-7.67 (m, 2H), 8 .73 (s, 1H), 9.51 (br, 1H)
MS (FAB +); 435 (M + 1)

7-fluoro -N- methyl -N- neopentyl-6 - [(oxetan-3 Iruami Roh) methyl] [1,3] thiazolo [3,2-a] benzimidazol-2-carboxy Samido 2 fumarate Reference Acetic acid (206 μl), oxetane-3-amine hydrochloride (267 mg) and triethylamine (301 μl) were added to a dichloroethane solution (15 ml) of the compound of Example 21 (250 mg), and the mixture was stirred at room temperature for 2.5 hours. Subsequently, sodium triacetoxyborohydride (458 mg) was added, and the mixture was stirred overnight at room temperature. After completion, the reaction solution was added to a saturated aqueous sodium hydrogen carbonate solution and extracted with chloroform. The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (eluent; chloroform, then chloroform: methanol: 28% aqueous ammonia = 9: 1: 0.1). Ethanol (30 ml) was added and dissolved in the purified product, fumaric acid (138 mg) was added, and the mixture was concentrated under reduced pressure. The crystallized residue was recrystallized from ethanol and ethyl acetate, and the resulting crystals were collected by filtration. The crystals collected by filtration were washed with a mixed solvent of ethanol and ethyl acetate (mixing ratio 1:10), and then dried under reduced pressure while heating at 60 ° C. to obtain the title compound (220 mg).
¹ H-NMR (DMSO-d ₆ ); 0.96 (s, 9H), 3.41-3.47 (m, 5H), 3.83 (s, 2H), 3.94-4.04 ( m, 1H), 4.33-4.37 (t, 2H), 4.59-4.63 (t, 2H), 6.62 (s, 1H), 7.49 (d, 1H), 8 .16 (d, 1H), 9.08 (s, 1H)
MS (FAB +); 405 (M + 1)

6 - {[(1,3-dioxolan-2-ylmethyl) amino] methyl} -7-fluoro -N- methyl -N- neopentyl [1,3] thiazolo [3,2-a] benzo imidazole -2 Acetic acid (206 μl) and (1,3-dioxolan-2-yl) methylamine (202 μl) were added to a dichloroethane solution (15 ml) of the compound of Carboxamide dihydrochloride Reference Example 21 (250 mg) and stirred at room temperature for 1 hour. . Subsequently, sodium triacetoxyborohydride (275 mg) was added and stirred at room temperature for 5 hours. Further, sodium triacetoxyborohydride (488 mg) was added, and the mixture was stirred at room temperature for 14 hours. After completion, the reaction solution was added to a saturated aqueous sodium hydrogen carbonate solution and extracted with chloroform. The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (eluent; chloroform, then chloroform: methanol: 28% aqueous ammonia = 9: 1: 0.1). Ethanol (10 ml) was added and dissolved in the purified product, 1M aqueous hydrochloric acid solution (1.49 ml) was added, and the mixture was concentrated under reduced pressure. The crystallized residue was recrystallized from ethanol and ethyl acetate, and the resulting crystals were collected by filtration. The crystals collected by filtration were washed with a mixed solvent of ethanol and ethyl acetate (mixing ratio 1: 5) and then dried under reduced pressure at 60 ° C. to obtain the title compound (310 mg).
¹ H-NMR (DMSO-d ₆ ); 0.97 (s, 9H), 3.20 (d, 2H), 3.42-3.47 (m, 5H), 3.85-3.94 ( m, 2H), 3.98-4.06 (m, 2H), 4.35 (s, 2H), 5.27 (t, 1H), 7.66 (d, 2H), 8.36 (d , 1H), 9.16 (s, 1H), 9.60 (br, 2H)
MS (FAB +); 435 (M + 1)

（試験法）
ｍＧｌｕＲ１に対する本発明化合物の効果は特許文献３記載の方法に準じて確認した。
本発明化合物の作用はｍＧｌｕＲ１に対する選択的、かつ強力な作用を有する６−アミノ−Ｎ−シクロヘキシル−Ｎ，３−ジメチルチアゾロ［３，２−ａ］ベンゾイミダゾール−２−カルボキサミドのトリチウムラベル体（特異活性；８１Ｃｉ／ｍｍｏｌ（Ａｍｅｒｓｈａｍ））を用いた結合実験により確認した。
上記化合物は、ｍＧｌｕＲ１α発現細胞を用いたフォスファチジルイノシトール（ＰＩ）加水分解系（Ｎａｔｕｒｅ ３８３，８９−９２，１９９６）においてグルタミン酸の反応に対しＩＣ５０＝２４ｎＭという高い阻害活性を有している。
（ラット小脳Ｐ２膜画分の作成）
ラット（Ｗｉｓｔａｒ、雄性、９−１２週齢）を断頭し、小脳を摘出した。重量を測定し、７−１０倍量の０．３２Ｍショ糖溶液でホモジナイズした。９００ｘｇで１５分間遠心を行い、上清を別の容器に保管した（氷中）。沈査を１回目と同量の０．３２Ｍショ糖溶液で再度ホモジナイズし９００ｘｇで１５分間遠心を行った。この時得られた上清と先に得られた上清を合わせ１５，０００ｘｇで２０分間遠心を行った。沈査を５ｍＭ Ｔｒｉｓ−ＨＣｌ、ｐＨ７．４でホモジナイズし、１５，０００ｘｇで１５分間遠心を行った。この操作をもう一度繰り返した。沈査を５０ｍＭ Ｔｒｉｓ−ＨＣｌ、ｐＨ７．４でホモジナイズし、１５，０００ｘｇで１５分間遠心を行った。沈査を適量の５０ｍＭ Ｔｒｉｓ−ＨＣｌ、ｐＨ７．４でホモジナイズし、小分けして−８０℃にて保存した。
（結合実験）
アッセイバッファーとして５０ｍＭ Ｔｒｉｓ−ＨＣｌ、２．５ｍＭ ＣａＣｌ２、ｐＨ７．４を用いた。［３Ｈ］−６−アミノ−Ｎ−シクロヘキシル−Ｎ，３−ジメチルチアゾロ［３，２−ａ］ベンゾイミダゾール−２−カルボキサミド、試験化合物及び約０．１ｍｇのラット小脳Ｐ２膜画分を全量で１００μＬになるように９６穴マイクロプレート内に懸濁し、室温（約２５℃）で４５分間インキュベーションを行った。インキュベーションの終了はＷｈａｔｍａｎ ＧＦ／Ｂ ｆｉｌｔｅｒを用いた濾過法で行った。放射能量は液体シンチレーションカウンターで測定した。競合実験には約２０ｎＭの［３Ｈ］−６−アミノ−Ｎ−シクロヘキシル−Ｎ，３−ジメチルチアゾロ［３，２−ａ］ベンゾイミダゾール−２−カルボキサミドを用い、特異結合は全結合量のうち１０μＭの６−｛［（２−メトキシエチル）アミノ］メチル｝−Ｎ−ネオペンチルチアゾロ［３，２−ａ］ベンゾイミダゾール−２−カルボキサミド（特許文献３ 実施例７５に記載の化合物）によって置換された部分とした。試験化合物の評価は、特異結合に及ぼす結合阻害率を求めて行った。
蛋白定量はＢＩＯ−ＲＡＤ ＤＣ ｐｒｏｔｅｉｎ ａｓｓａｙ（ＢＩＯ−ＲＡＤ）を用いた。標準物質として牛血清アルブミンを用い行った。
結果は表２に示す。
参考文献：
Ｔｈｏｍｓｅｎ−Ｃ；Ｍｕｌｖｉｈｉｌｌ−ＥＲ；Ｈａｌｄｅｍａｎ−Ｂ；Ｐｉｃｋｅｒｉｎｇ−ＤＳ；Ｈａｍｐｓｏｎ−ＤＲ；Ｓｕｚｄａｋ−ＰＤ、Ａｐｈａｒｍａｃｏｌｏｇｉｃａｌ ｃｈａｒａｃｔｅｒｉｚａｔｉｏｎ ｏｆ ｔｈｅ ｍＧｌｕＲ１ ａｌｐｈａ ｓｕｂｔｙｐｅ ｏｆ ｔｈｅ ｍｅｔａｂｏｔｒｏｐｉｃ ｇｌｕｔａｍａｔｅ ｒｅｃｅｐｔｏｒ ｅｘｐｒｅｓｓｅｄ ｉｎ ａ ｃｌｏｎｅｄ ｂａｂｙ ｈａｍｓｔｅｒ ｋｉｄｎｅｙ ｃｅｌｌ ｌｉｎｅ．、Ｂｒａｉｎ−Ｒｅｓ．１９９３ Ａｕｇ １３；６１９（１−２）：２２−８
試験例２：神経因性疼痛に対する抑制効果
１）ストレプトゾトシン（Ｓｔｒｅｐｔｏｚｏｔｏｃｉｎ、以下ＳＴＺという）誘発糖尿病モデル
実験は既報（Ｐｈａｒｍａｃｏｌ Ｂｉｏｃｈｅｍ Ｂｅｈａｖ ３９、５４１−５４４，１９９１）の一部を改変して行った。４週齢ＩＣＲマウスに対してＳＴＺを２００ｍｇ／ｋｇ腹腔内投与する。投与２週間後の午後にｔａｉｌ ｐｉｎｃｈ ｔｅｓｔのｐｒｅ試験を行い、反応潜時が３秒以下の動物についてのみ翌日の実験に供した。
対照化合物には、チアゾロベンゾイミダゾールのベンゼン環上に置換アミノメチル基を有する化合物として対照化合物Ａ、Ｂ、及びＣを選択した。
本発明化合物及び対照化合物Ｃは１０ｍｇ／ｋｇを経口投与により負荷し、投与後３０分でｔａｉｌ ｐｉｎｃｈ ｔｅｓｔを行った。一方対照化合物Ａ及びＢは１００ｍｇ／ｋｇを経口投与し同様に評価した。
なお、ＳＴＺを負荷していない正常マウスでは、本試験において平均６−７秒の反応潜時を示す。今回試験に用いたＳＴＺ負荷マウスは、明らかな痛覚閾値の低下が認められた反応潜時３秒以下のものを用いた。
結果を表２に示す。
なお、糖尿病性神経因性疼痛薬として承認され、市販されているメキシレチンは約３秒である。

上記試験によって、本発明化合物は、ｍＧｌｕＲ１に特異的に結合する化合物であることが確認された。
また、本発明化合物は、１０ｍｇ／ｋｇの経口投与で平均反応潜時差が全て２秒以上を示したことから、糖尿病による神経因性疼痛の治療効果を有することが確認された。
一方、対照化合物Ａ及びＢは１００ｍｇ／ｋｇの経口投与で平均反応潜時差が約１秒以下であった。
従って、本発明化合物は、対照化合物Ａ、Ｂに比べ、経口活性が少なくとも１０倍以上優れた化合物であり、経口剤として有用な化合物であることが確認された。一方、対照化合物Ｃについては、２秒以上の反応潜時差を示した。
２）Ｌ５／Ｌ６脊髄神経結紮ラット
実験は既報（ＰＡＩＮ ５０，３５５−３６３，１９９２）の一部を改変して行った。ＳＤラットを用い、ペントバルビタール麻酔下で左側腰神経（Ｌ５およびＬ６）を絹糸で結紮した。術後７日目に以下の試験を実施した。
薬物を１０ｍｇ／ｋｇ経口投与し、３０分後にｖｏｎ Ｆｒｅｙ ｈａｉｒ（ＶＦＨ）ｔｅｓｔを行い、機械侵害刺激に対する痛覚閾値を求めた。測定は左右の後肢で実施した。
なお、擬手術ラットの痛覚閾値は、左右差はなく、平均値で１７−２０ｇ（ｌｏｇ（ｇ）：１．２３−１．３０）であり、Ｌ５／Ｌ６脊髄神経結紮ラットの手術側足で機械侵害刺激に対する痛覚閾値の低下が認められた。
有意差検定は、Ｄｕｎｎｅｔｔ法を用い、左右それぞれの足でコントロール群と薬物投与群との間で行った。
結果を表３に示す。

表３に示された本発明化合物は、ＳＴＺ誘発糖尿病モデルで２秒以上の反応潜時差を示した対照化合物Ｃに対し、約８倍〜５０倍以上の作用を示した。
また、上記本発明化合物は、特許文献２で神経圧迫による痛覚閾値の低下作用を有することが確認されたアニリン性アミノ基を有する対照化合物Ｄに対し４〜３０倍の作用を示した。
３．遺伝毒性
本発明化合物の遺伝子突然変異誘発性は、細菌を用いる復帰突然変異試験にて確認した。
試験方法は医薬品の遺伝毒性試験ガイドライン（医薬審 第１６０４号、平成１１年１１月１日）に従い、代謝活性化系の存在下および非存在下に、プレインキュベーション法により実施した。ただし、試験菌株はＳａｌｍｏｎｅｌｌａ ｔｙｐｈｉｍｕｒｉｕｍ ＴＡ９８およびＴＡ１００のみ使用した。
（細菌を用いる復帰突然変異試験）
試験管に、０．１Ｍリン酸ナトリウム緩衝液（ｐＨ７．４）０．５ｍＬ、一晩培養した試験菌懸濁液０．１ｍＬおよび試験物質溶液０．１ｍＬを加え、３７℃で２０分間振盪（６０往復／分）した後、約４５℃に保温した軟寒天２ｍＬを加えて最少グルコース寒天平板培地（プレート）に拡げ、３７℃で約４８時間培養した。代謝活性化試験の場合は、０．１Ｍリン酸ナトリウム緩衝液の代わりに同量のＳ９Ｍｉｘを加え同様に操作した。
結果
代謝活性化試験に用いたＳ９ＭｉｘはＳ−９／ｃｏｆａｃｔｏｒ Ａ ｓｅｔ（ｐｈｅｎｏｂａｒｂｉｔａｌおよび５，６−ｂｅｎｚｏｆｌａｖｏｎｅで薬物代謝酵素を誘導したラット肝ホモジネートの９０００×ｇ上清とＣｏｆａｃｔｏｒ，Ａｍｅｓ試験用，オリエンタル酵母株式会社）を用いて調製した．Ｓ９Ｍｉｘ中のＳ９量は０．１ｍＬ／ｍＬとした。溶媒はｄｉｍｅｔｈｙｌｓｕｌｐｈａｔｅを用いた。
４８時間培養後プレート上に生じたコロニーを計数した。
被験物質で処理したプレートの復帰変異コロニー数（平均値）が溶媒対照の復帰変異コロニー数（平均値）の２倍以上に増加し、用量依存性が認められ，再現性が確認された場合に遺伝子突然変異誘発性を有すると判断した。
上記試験において、実施例１及び実施例２の化合物は遺伝子突然変異誘発性を有さないことが確認された。一方、アニリン性アミノ基を有する対照化合物Ｄは遺伝子突然変異誘発性を有することが確認された。
これらの結果から、本発明化合物はアニリン性アミノ基を有さないことから遺伝子突然変異誘発性がなく、特許文献１乃至４からは予想できない優れた経口活性、特に神経圧迫による神経因性疼痛抑制効果を有することを確認した。 7-fluoro -N- methyl -N- neopentyl-6 - {[(tetrahydro -2H- pyrazolone down-4-ylmethyl) amino] methyl} [1,3] thiazolo [3,2-a] benzoyl imidazole-2- Acetic acid (206 μl), (tetrahydro-2H-pyran-4-ylmethyl) amine hydrochloride (328 mg), and triethylamine (301 μl) were added to a dichloroethane solution (15 ml) of the compound of carboxamide dihydrochloride Reference Example 21 (250 mg) at room temperature. The mixture was stirred for 1.5 hours. Subsequently, sodium triacetoxyborohydride (458 mg) was added, and the mixture was stirred overnight at room temperature. After completion, the reaction solution was added to a saturated aqueous sodium hydrogen carbonate solution and extracted with chloroform. The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (eluent; chloroform, then chloroform: methanol: 28% aqueous ammonia = 9: 1: 0.1). Ethanol (30 ml) was added and dissolved in the purified product, 1M aqueous hydrochloric acid solution (1.34 ml) was added, and the mixture was concentrated under reduced pressure. The crystallized residue was recrystallized from ethanol and ethyl acetate, and the resulting crystals were collected by filtration. The crystals collected by filtration were washed with a mixed solvent of ethanol and ethyl acetate (mixing ratio 1:10), and then dried under reduced pressure while heating at 60 ° C. to obtain the title compound (240 mg).
¹ H-NMR (DMSO-d ₆ ); 0.97 (s, 9H), 1.16-1.28 (m, 2H), 1.70-1.73 (m, 2H), 1.99- 2.06 (m, 1H), 2.87-2.90 (m, 2H), 3.24-3.30 (m, 2H), 3.42-3.47 (m, 5H), 3. 83-3.87 (m, 2H), 4.29 (br, 2H), 7.67 (d, 2H), 8.37 (d, 1H), 9.14 (s, 1H), 9.39 -9.47 (m, 2H)
MS (FAB +); 447 (M + 1)
In addition to those described in the above examples, the compounds shown in Table 1 below were prepared using the above-mentioned production methods, production methods of Reference Examples and Examples, production methods known to those skilled in the art, and variations thereof. Can be obtained.

(Test method)
The effect of the compound of the present invention on mGluR1 was confirmed according to the method described in Patent Document 3.
The action of the compound of the present invention is a tritium-labeled form of 6-amino-N-cyclohexyl-N, 3-dimethylthiazolo [3,2-a] benzimidazole-2-carboxamide having a selective and strong action on mGluR1 ( Specific activity; 81 Ci / mmol (Amersham)) was used to confirm the binding experiment.
The above compound has a high inhibitory activity of IC50 = 24 nM for the reaction of glutamic acid in a phosphatidylinositol (PI) hydrolysis system (Nature 383, 89-92, 1996) using mGluR1α-expressing cells.
(Creation of rat cerebellar P2 membrane fraction)
Rats (Wistar, male, 9-12 weeks old) were decapitated and the cerebellum was removed. Weighed and homogenized with 7-10 volumes of 0.32M sucrose solution. Centrifugation was performed at 900 × g for 15 minutes, and the supernatant was stored in another container (in ice). The precipitate was homogenized again with the same amount of 0.32M sucrose solution as the first time and centrifuged at 900 × g for 15 minutes. The supernatant obtained at this time and the previously obtained supernatant were combined and centrifuged at 15,000 × g for 20 minutes. The precipitate was homogenized with 5 mM Tris-HCl, pH 7.4, and centrifuged at 15,000 × g for 15 minutes. This operation was repeated once more. The precipitate was homogenized with 50 mM Tris-HCl, pH 7.4, and centrifuged at 15,000 × g for 15 minutes. The precipitate was homogenized with an appropriate amount of 50 mM Tris-HCl, pH 7.4, subdivided and stored at -80 ° C.
(Binding experiment)
As an assay buffer, 50 mM Tris-HCl, 2.5 mM CaCl 2, pH 7.4 was used. [3H] -6-amino-N-cyclohexyl-N, 3-dimethylthiazolo [3,2-a] benzimidazole-2-carboxamide, test compound and about 0.1 mg of rat cerebellar P2 membrane fraction in total amount The suspension was suspended in a 96-well microplate so as to be 100 μL, and incubated at room temperature (about 25 ° C.) for 45 minutes. The incubation was terminated by a filtration method using Whatman GF / B filter. The amount of radioactivity was measured with a liquid scintillation counter. About 20 nM [3H] -6-amino-N-cyclohexyl-N, 3-dimethylthiazolo [3,2-a] benzimidazole-2-carboxamide was used for the competition experiment. Replaced with 10 μM 6-{[(2-methoxyethyl) amino] methyl} -N-neopentylthiazolo [3,2-a] benzimidazole-2-carboxamide (compound described in Patent Document 3 Example 75) It was made part. The test compound was evaluated by determining the binding inhibition rate on specific binding.
BIO-RAD DC protein assay (BIO-RAD) was used for protein quantification. Bovine serum albumin was used as a standard substance.
The results are shown in Table 2.
References:
Thomsen-C; Mulvihill-ER; Haldeman-B; Pickering-DS; Hampson-DR; Suzdak-PD, Apharmacological characterization of the mGluR1 alpha subtype of the metabotropic glutamate receptor expressed in a cloned baby hamster kidney cell line. Brain-Res. 1993 Aug 13; 619 (1-2): 22-8.
Test Example 2: Inhibitory Effect on Neuropathic Pain 1) Streptozotocin (hereinafter referred to as STZ) -induced diabetes model The experiment was carried out by modifying a part of a previously reported report (Pharmacol Biochem Behav 39, 541-544, 1991). STZ is administered intraperitoneally to 4-week-old ICR mice at 200 mg / kg. A tail pin test pre-test was conducted in the afternoon 2 weeks after administration, and only the animals having a reaction latency of 3 seconds or less were subjected to the experiment on the next day.
Control compounds A, B, and C were selected as control compounds having a substituted aminomethyl group on the benzene ring of thiazolobenzimidazole.
The compound of the present invention and the control compound C were loaded with 10 mg / kg by oral administration, and tail pin test was performed 30 minutes after the administration. On the other hand, the control compounds A and B were orally administered at 100 mg / kg and evaluated in the same manner.
In normal mice not loaded with STZ, an average response latency of 6-7 seconds is shown in this test. The STZ-loaded mice used in this study were those with a response latency of 3 seconds or less in which a clear decrease in pain threshold was observed.
The results are shown in Table 2.
Note that mexiletine, which is approved as a diabetic neuropathic pain drug and marketed, is about 3 seconds.

From the above test, the compound of the present invention was confirmed to be a compound that specifically binds to mGluR1.
In addition, since the compounds of the present invention showed an average response latency difference of 2 seconds or more after oral administration of 10 mg / kg, it was confirmed that they have a therapeutic effect on neuropathic pain due to diabetes.
On the other hand, control compounds A and B had an average response latency difference of about 1 second or less after oral administration of 100 mg / kg.
Therefore, it was confirmed that the compound of the present invention is a compound having an oral activity that is at least 10 times better than the control compounds A and B, and is useful as an oral preparation. On the other hand, for control compound C, a reaction latency difference of 2 seconds or more was shown.
2) L5 / L6 spinal nerve ligation rat The experiment was performed by modifying a part of the previous report (PAIN 50, 355-363, 1992). Using SD rats, the left lumbar nerve (L5 and L6) was ligated with silk thread under pentobarbital anesthesia. On the 7th day after the operation, the following tests were conducted.
The drug was orally administered at 10 mg / kg, and von Frey hair (VFH) test was performed 30 minutes later to determine the pain threshold for mechanical nociceptive stimulation. Measurements were performed on the left and right hind limbs.
The pain threshold of sham-operated rats is 17-20 g (log (g): 1.23-1.30) on average without any difference between the left and right sides, and on the surgical side foot of L5 / L6 spinal nerve ligated rats. A decrease in pain threshold for mechanical nociceptive stimuli was observed.
The significant difference test was performed between the control group and the drug administration group using the Dunnett method with the left and right feet.
The results are shown in Table 3.

The compounds of the present invention shown in Table 3 exhibited an effect of about 8 times to 50 times or more with respect to the control compound C which showed a response latency difference of 2 seconds or more in the STZ-induced diabetes model.
In addition, the compound of the present invention showed a 4 to 30-fold effect on the control compound D having an aniline amino group, which was confirmed in Patent Document 2 to have an effect of lowering the pain threshold by nerve compression.
3. Genotoxicity The gene mutagenicity of the compounds of the present invention was confirmed by a reverse mutation test using bacteria.
The test method was carried out by the preincubation method in the presence and absence of a metabolic activation system in accordance with the genotoxicity test guidelines for pharmaceutical products (Pharmaceutical Examination No. 1604, November 1, 1999). However, only Salmonella typhimurium TA98 and TA100 were used as test strains.
(Reverse mutation test using bacteria)
To a test tube, add 0.5 mL of 0.1 M sodium phosphate buffer (pH 7.4), 0.1 mL of a test bacterial suspension cultured overnight and 0.1 mL of a test substance solution, and shake at 37 ° C. for 20 minutes ( After 60 reciprocations / min), 2 mL of soft agar kept at about 45 ° C. was added, spread on a minimal glucose agar plate medium (plate), and cultured at 37 ° C. for about 48 hours. In the case of the metabolic activation test, the same operation was performed by adding the same amount of S9Mix instead of 0.1 M sodium phosphate buffer.
Results S9Mix used for the metabolic activation test was S-9 / cofactor A set (Phenobarbital and rat liver homogenate induced with 9,6-benzoflavone, 9000 × g supernatant and Cofactor, Ames test, Oriental yeast Co., Ltd.). The amount of S9 in S9Mix was 0.1 mL / mL. Dimethylsulfate was used as the solvent.
Colonies generated on the plate after 48 hours of culture were counted.
When the number of revertant colonies (average value) on the plate treated with the test substance increases to more than twice the number of revertant colonies (average value) in the solvent control, and when dose dependency is observed and reproducibility is confirmed It was judged to have gene mutagenicity.
In the above test, it was confirmed that the compounds of Example 1 and Example 2 were not gene mutagenic. On the other hand, it was confirmed that the control compound D having an aniline amino group has gene mutagenicity.
From these results, since the compound of the present invention has no aniline amino group, it has no gene mutagenicity, and has excellent oral activity that cannot be predicted from Patent Documents 1 to 4, particularly suppression of neuropathic pain due to nerve compression. It was confirmed to have an effect.

The invention's effect

The compound of the present invention is a compound having a strong action on a metabotropic glutamate receptor and excellent in oral activity, and can also be used in oral administration.
Therefore, the compound of the present invention is a disease considered to involve the mGluR1 receptor, such as epilepsy, pain, suppression of neuronal cell death, benzodiazepine withdrawal syndrome, Parkinson's disease, migraine, anxiety disorder, cerebral infarction (preferably Is a prophylactic / therapeutic agent for infarct lesions administered in the acute phase of cerebral infarction) or neuropathic pain (preferably diabetic neuropathic pain, postherpetic neuralgia, cancer pain, postoperative pain) Useful.

Claims (6)

An aminomethyl-substituted fluorothiazolobenzimidazole derivative represented by the following general formula (I) or a salt thereof.

(Here, the symbols in the formula have the following meanings.
R ¹ : optionally substituted oxygen-containing saturated heterocycle-, optionally substituted sulfur-containing saturated heterocycle-, optionally substituted cycloalkyl, R ⁶ -O-, or R ⁷ -S-
Alk1: Lower alkylene m: 0 or 1
Alk2: Lower alkylene which may be substituted with an oxo group n: 0 or 1
X: a bond, O, S, or —NR ⁵ —
R ³ : H, lower alkyl, halogeno lower alkyl, lower alkenyl, lower alkynyl, optionally substituted cycloalkyl, cyano, or saturated heterocyclic ring
R ² , R ⁴ , R ⁵ , R ⁶ and R ⁷ : the same or different, H or lower alkyl) In the general formula (I), R ¹ is oxetane- or dioxolane-, R ² is H, R ³ is neopentyl, X is a bond, R ⁴ is methyl, Alk1 is methylene, and n is 0. The derivative or its salt as described. 5-fluoro-N-methyl-N-neopentyl-6-[(oxetane-3-ylamino) methyl] thiazolo [3,2-a] benzimidazole-2-carboxamide;
6-{[(1,3-dioxolan-2-ylmethyl) amino] methyl} -5-fluoro-N-methyl-N-neopentylthiazolo [3,2-a] benzimidazole-2-carboxamide; salt. A pharmaceutical composition comprising the aminomethyl-substituted fluorothiazolobenzimidazole derivative or a pharmaceutically acceptable salt thereof according to any one of claims 1 to 3 as an active ingredient. A therapeutic agent for neuropathic pain comprising the aminomethyl-substituted fluorothiazolobenzimidazole derivative according to any one of claims 1 to 3 or a pharmaceutically acceptable salt thereof as an active ingredient. Treatment of neuropathic pain by administering to a patient an effective amount of a pharmaceutical composition comprising the aminomethyl-substituted fluorothiazolobenzimidazole derivative according to claims 1 to 3 or a pharmaceutically acceptable salt thereof and a carrier. Method.