Benzoxepin derivatives

Abstract: A benzoxepin derivative represented by the formula(I): wherein R represents a heterocyclyc group, and salts thereof; a process for production thereof comprising the steps of reducing an oxime represented by the formula (V): wherein R has the same meaning as defined in the formula (I), and hydrolyzing the intermediate produced of the above reduction; and pharmaceuticals comprising the compound (I).

Description: The present invention relates to benzoxepin derivatives, process for the production of these, and pharmaceutical preparations containing same. There are two types diabetes known, i.e., an insulin-dependent type I and an insulin-non-dependent type II. The type II diabetes, which afflicts 90% of all diabetics, is treated by using sulfonyl urea compounds, sulfonyl amide compounds and biguanide compounds in combination with dietetics, but these agents cause severe hypoglycemia, due to an overstrong blood sugar-lowering effect, and hepatitic disorders. In view of the above disadvantageous circumstances, the present inventors carried out research into the development of oral pharmaceuticals for the treatment of the diabetics, which do not have the above-mentioned drawbacks, and found 2-phenyl-benzoxepin derivatives having an advantageous blood sugar lowering activity and activity against platelet aggregation (Japanese Patent Application No. 63-107972) and EP-A-250265. Accordingly, an object of the present invention is to provide novel benzoxepin derivatives having a very good blood sugar lowering activity and activity against platelet aggregation, but surprisingly, not exhibiting a side effect such as a sleep-prolonging action. More specifically, the present invention provides benzoxepin derivatives represented by the formula (I): wherein R represents a heterocyclyl group defined below,, and salts thereof. The present invention also provides a process for the production of benzoxepin derivatives of the formula (I) comprising the steps of: reducing an oxime represented by the formula (V): wherein R has the same meaning as defined for the formula (I); and hydrolyzing the intermediate product of the above reduction. Moreover, the present invention provides a pharmaceutical preparation for lowering a blood sugar level comprising a benzoxepin derivative of the formula (I) or a salt thereof, and a pharmaceutically acceptable carrier. The present invention still further provides a pharmaceutical preparation for inhibiting platelet aggregation, comprising a benzoxepin derivative of the formula (I), or a salt thereof, and a pharmaceutically acceptable carrier. The heterocyclyl group represented by R is a pyridyl group, a pyrazinyl group, a pyrimidinyl group, pyridazinyl group, a pyrrolyl group, an imidazolyl group, a furyl group or a thienyl group. Preferably, the substituent R is a pyridyl group such as a 2-pyridyl, 3-pyridyl or 4-pyridyl group, or a pyrazinyl group. The salts of the benzoxepin derivative (I) are, for example, acid addition salts, for example, salts of an inorganic acid such as hydrochloric acid, hydrogen bromide, hydrogen iodide, sulfuric acid or of nitric acid, an organic acid such as formic acid, acetic acid, propionic acid, or an organic sulfonic acid such as benzene sulfonic acid or toluene sulfonic acid. The present benzoxepin derivatives (I) can be produced, for example, as follows. First, according to the same procedure for the synthesis of the compound represented by the formula (III), wherein R represents a phenyl group, as described in P. Bennett et al., J. Chem. Soc. Parkin. Trans. I, (12) 2990 (1979), a compound represented by the formula (II): wherein R has the same meaning as defined under the formula (I), is subjected to a cyclopropanation reaction using a cyclopropanation agent such as trimethylsulfoxonium iodide or trimethylsulfonium iodide in a medium such as dimethylsulfoxide, N,N-dimethylformamide or THF , at a temperature of, for example, 20°C to 50°C, preferably 20°C to 25°C, to obtain a oxabicycloheptane derivative represented by the formula (III): wherein R has the same meaning as defined under the formula (I). Next, the compound (III) is treated with tri-n-butyltinhydride or azobisisobutyronitrile in an inert solvent such as benzene or toluene to obtain an oxepin derivative represented by the formula (IV): wherein R has the same meaning as defined under the formula (I). The compound (IV) is then reacted with n-butylnitrite under the presence of hydrogen chloride in an inert solvent such as tetrahydrofuran, ethyl ether, methylene chloride, or a mixture thereof, to obtain an oxime represented by the formula (V): wherein R has the same meaning as described under the formula (I). Finally, this oxime (V) is reduced and the reduced product is then hydrolyzed under an alkaline condition to obtain a benzoxepin derivative of the present invention represented by the formula (I): wherein R has the same meaning as defined above, in a form of a mixture of steric isomers. Preferably, the above-mentioned reduction is carried out in two steps, i.e., reduction by zinc powder/acetic acid/ammonium acetate in acetic anhydride, followed by reduction using sodium borohydride in a solvent such as methanol, ethanol, 2-propanol, or diglyme. The mixture of steric isomers can be separated to four steric isomers, by a conventional procedure or a combination thereof, such as silica gel chromatography and recrystallization. Examples The present invention will now by further illustrated by the following Examples and Reference Examples. Note, the physico-chemical properties of compounds prepared in the Examples and Reference Examples are shown in the Tables. Where a mixture of steric isomers can be separated, the physico-chemical properties of each isolated isomer, which isomers are labeled "a", "b", "c", and "d", are shown in the Tables. Example 1. 4-amino-5-hydroxy-2-(2-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin (Compounds 1a, 1b and 1c) First, 894 mg (3 mmole) of 4-acetylamino-5-hydroxy-2-(2-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin (prepared in Reference Example 5) was dissolved in 30 ml of methanol, then 30 ml of 10% sodium hydroxide aqueous solution was added thereto, and the mixture was heated to reflux. After evaporating off the methanol, the residue was extracted with methylene chloride, and the extract dried over anhydrous magnesium sulfate. After filtration of the mixture, the filtrate was concentrated and the residue was applied to a silica gel column which was then eluted with methylene chloride/methanol (20:1) to obtain 719 mg (yield 93.6%) of the title compound 1a. Similarly, compound 1b (yield 92.8%) and compound 1c (yield 97.7%) were obtained from compound 9b and compound 9c in Reference Example 5, respectively. Example 2. 4-amino-5-hydroxy-2-(3-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin (Compounds 2a, 2b, and 2c) In the same manner as described in Example 1, compound 2a (yield 93.8%) and compound 2b (yield 95.6%) were obtained from compounds 14a and 14b in Reference Example 10, respectively. Further, a mixture of the compounds 2b and 2c was obtained from a mixture of compounds 14b and 14c in Reference Example 10, and the mixture was subjected to recrystallization in methylene chloride to obtain a compound 2c (yield 15.1%) as crystal. Example 3. 4-amino-5-hydroxy-2-(4-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin (Compounds 3c and 3d) In the same manner as described in Example 1, a mixture of compounds 3a and 3d was obtained from compound 19a (Reference Example 15), and the mixture was subjected to recrystallization to obtain a compound 3d (yield 35.0%) as a crystal. On the other hand, a mixture of compounds 3b and 3c was obtained from compound 19b (Reference Example 15) and the mixture was subjected to recrystallization in methylene chloride to obtain a compound 3c (yield 31.3%) as a crystal. Example 4. 4-amino-5-hydroxy-2-pyrazinyl-2,3,4,5-tetrahydro-1-benzoxepin (Compound 4c) In the same manner as described in Example 1, compound 4c (yield 95.7%) was obtained from compound 24c in Reference Example 20. Reference Examples The starting materials used in the Examples described above were prepared as described in the following Reference Examples. Reference Example 1. 3,4-benzo-5-oxo-1-(2-pyridyl)-2-oxabicyclo[4,1,0]heptane (Compound 5) First, 9 g (225 mmoles) of 60% sodium hydride was suspended in 150 ml of dimethylsulfoxide, 49.5 g (225 mmoles) of trimethylsulfoxonium iodide was then added in portions thereto, and the mixture was stirred at a room temperature for one hour. Next a solution of 33.5 g (150 mmoles) of 4-oxo-2-(2-pyridyl)-1-benzopyran in 300 ml of dimethylsulfoxide was added to the reaction mixture, and the mixture was stirred at a room temperature for 5 hours. The reaction mixture was poured over 1 liter of ice water, and the whole was extracted three times with 500 ml of diethyl ether. The extract was washed with saturated sodium chloride aqueous solution, dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated, and the residue applied to a silica gel column, which was then eluted with methylene chloride/ethyl acetate (4:1) to obtain 18.2 g (yield 51.2%) of the title compound. Reference Example 2. 2-(2-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 6) First, 14.4 g (60 mmoles) of 3,4-benzo-5-oxo-1-(2-pyridyl)-2-oxabicyclo[4,1,0]heptane were dissolved in 300 ml of benzene, 17.7 ml (66 mmoles) of tri-n-butyltinhydride and 4.92 g (30 mmoles) of azobisisobutylonitrile were then added thereto, and the mixture was heated to reflux for 2 hours. After cooling, the reaction mixture was washed with water, dried over anhydrous magnesium sulfate, and filtered. The filtrate was concentrated, and the residue applied to a silica gel column, which was then eluted with hexane/ethyl acetate (2:1) to obtain 12.6 g (yield 88.1%) of the title compound. Reference Example 3. 4-hydroxyimino-2-(2-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 7) First, 10.8 g (45 mmoles) of 2-(2-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one prepared in Reference Example 2 was dissolved in a mixture of 200 ml of methylene chloride and 150 ml of tetrahydrofuran, 15 ml of ethyl ether saturated with hydrogen chloride was added thereto, and the mixture then cooled to 0°C. Next, 16 ml (135 mmoles) of n-butyl nitrite was dropwise added to the mixture, and the mixture was allowed to stand in a freezer at -15°C to -20°C for 24 hours. The mixture was then concentrated, and water was added to the residue. The mixture was alkalized with 1N sodium hydroxide aqueous solution and extracted with methylene chloride, and the extract was then dried over anhydrous magnesium sulfate and filtered. The filtrate was concentrated, and the residue was applied to a silica gel column, which was then eluted with methylene chloride/ethyl acetate (2:1) to obtain 9.45 g (yield 78.4%) of the title compound. Reference Example 4. 4-N-acetylamino-2-(2-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compounds 8a and 8b) First, 8.84 g (33 mmoles) of 4-hydroxyimino-2-(2-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one prepared in Reference Example 3 were dissolved in 330 ml of acetic anhydride, 6.40 g (99 mmoles) of zinc powder and 7.62 g (99 mmoles) of ammonium acetate were added thereto, and 5.7 ml (99 mmoles) of acetic acid was dropwise added to the mixture at a room temperature. The reaction mixture was stirred at a room temperature for 2 hours, and then concentrated. The residue was dissolved in ethyl acetate/methylene chloride (2:1) and filtered to remove zinc powder. The filtrate was washed with sodium bicarbonate aqueous solution and saturated sodium chloride aqueous solution, and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated, and the residue was applied to a silica gel column, which was then eluted with methylene chloride/methanol (30:1) to obtain 9.6 g (yield 87.0%) of the title compounds as a mixture of steric isomers 8a and 8b (ratio 2:1). The mixture was then subjected to crystallization in ethyl acetate to obtain 4.2 g of a crystal (Compound 8a) and 4.3 g of a mother liquid residue containing the compounds 8a and 8b at a ratio of 1:2. Reference Example 5. 4-N-acetylamino-5-hydroxy-2-(2-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin (Compounds 9a, 9b and 9c) First, 2.96 g (10 mmoles) of 4-N-acetylamino-2-(pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 8a) prepared in Reference Example 4 were dissolved in 100 ml of methanol, 491 mg (13 mmoles) of sodium borohydride added thereto at -20°C, and the mixture stirred for 4 hours. To the reaction mixture was added an ammonium chloride aqueous solution, and the mixture was concentrated. Water was added to the residue, and the mixture was extracted with methylene chloride. The extract was dried over anhydrous magnesium sulfate, filtered and concentrated. The residue was applied to a silica gel column, which was then eluted with methylene chloride/methanol (20:1) to obtain stereoisomers 9a and 9b of the title compounds at amounts of 910 mg (yield 30.5%) and 1.83 g (yield 61.4%), respectively. The same procedure was repeated using a mixture of stereoisomers 8a and 8b (1:2) prepared in Reference Example 3, to obtain a mixture of stereoisomers 9a, 9b and 9c of the title compounds. The mixture was then separated by column chromatography using silica gel/methylene chloride-methanol (10:1) to obtain compound 9c. Reference Example 6. 3,4-benzo-5-oxo-1-(3-pyridyl)-2-oxabicyclo[4,1,0]heptane (Compound 10) The title compound was synthesized according to the same procedure as described in Reference Example 1 (yield 55.8%). Reference Example 7. 2-(3-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 11) The title compound was synthesized according to the same procedure as described in Reference Example 2 (yield 71.4%). Reference Example 8. 4-hydroxyimino-2-(3-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 12) The title compound was synthesized according to the same procedure as described in Reference Example 3 (yield 66.0%). Reference Example 9. 4-N-acetylamino-2-(3-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compounds 13a and 13b) The title compounds were synthesized according to the same procedure as described in Reference Example 4, and a mixture of stereoisomers 13a and 13b (ratio of 13a:13b = 2.3:1) was obtained. The mixture was subjected to crystallization in ethyl acetate to obtain a crystal (13a) and a mother liquid residue (13a:13b = 1:1). Reference Example 10. 4-N-acetylamino-5-hydroxy-2-(3-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin (Compounds 14a, 14b and 14c) According to the same procedure as described in Reference Example 5, but starting from compound 13a prepared in Reference Example 9, stereoisomers 14a and 14b of the title compounds were obtained at yields of 56.2% (14a) and 27.1% (14b). Moreover, starting from a mixture of sterieoisomers (13a:13b = 1:1) prepared in Reference Example 9, a mixture of stereoisomers 14a, 14b and 14c of the title compounds was obtained. The mixture was subjected to column chromatography according to the same procedure as in Reference Example 5, to obtain a mixture of stereoisomers 14b and 14c (ratio 2:3). Reference Example 11. 3,4-benzo-5-oxo-1-(4-pyridyl)-2-oxabicyclo[4,1,0]heptane(Compound 15) The title compound was synthesized according to the same procedure as described in Reference Example 1 (yield 46.1%). Reference Example 12. 2-(4-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 16) The title compound was synthesized according to the same procedure as described in Reference Example 2 (yield 89.1%). Reference Example 13. 4-hydroxyimino-2-(4-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 17) The title compound was synthesized according to the same procedure as described in Reference Example 3 (yield 53.0%). Reference Example 14. 4-N-acetylamino-2-(4-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compounds 18a and 18b) The same procedure as described in Reference Example 4 was repeated to obtain a mixture of stereoisomers 18a and 18b (ratio 3:1) of the title compounds. The mixture was subjected to crystallization in ethyl acetate to obtain a crystal (18a) and a mother liquid residue (18a:18b = 2:1). Reference Example 15. 4-N-acetylamino-5-hydroxy-2-(4-pyridyl)-2,3,4,5-tetrahydro-1-benzoxepin (Compounds 19a and 19b) According to the same procedures described in Reference Example 5, but starting from compound 18a prepared in Reference Example 14, stereoisomers 19a (yield 63.2%) and 19b (yield 35.6%) of the title compounds were obtained. Reference Example 16. 3,4-benzo-5-oxo-1-pyrazinyl-2-oxabicyclo[4,1,0]heptane (Compound 20) The title compound was synthesized according to the same procedure as described in Reference Example 1 (yield 40.3%). Reference Example 17. 2-pyrazinyl-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 21) The title compound was synthesized according to the same procedure as described in Reference Example 2 (yield 62.5%). Reference Example 18. 4-hydroxyimino-2-pyrazinyl-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compound 22) The title compound was synthesized according to the same procedure as described in Reference Example 3 (yield 49.1%). Reference Example 19. 4-N-acetylamino-2-pyrazinyl-2,3,4,5-tetrahydro-1-benzoxepin-5-one (Compounds 23a and 23b) According to the same procedure as described in Reference Example 4, a mixture of stereoisomers 23a and 23b (ratio 2.5:1) of the title compounds was obtained at a total yield of 75.8%. The mixture was subjected to crystallization in ethyl acetate, to obtain crystal (23a) and a mother liquid residue (23a:23b = 1:1.2). Reference Example 20. 4-N-acetylamino-5-hydroxy-2-pyrazinyl-2,3,4,5-tetrahydro-1-benzoxepin (Compound 24c) According to the same procedure as described in Reference Example 5, but starting from a mixture of stereoisomers 23a and 23b (1:1.2) prepared in Reference Example 19, a mixture of sterieoisomers was obtained. The mixture was subjected to recrystallization in ethyl acetate to obtain the title compound 24c at a yield of 39.2%. The above listed materials were thoroughly mixed and then filled in a gelatin capsule by a conventional procedure. The above-listed ingredients were mixed and pressed to form a tablet, by a conventional procedure. The blood sugar-lowering activity, activity against platelet aggregation, and sleep-prolonging action of the present compounds were tested according to the following methods. 1. Blood sugar-lowering activity Male mice 5 to 6 weeks old were starved for 24 hours, and the test compound was orally administrated in the form of a CMC suspension. Then 30 minutes after the administration, a blood sample was taken from the eyeground vessel and immediately centrifuged, and the glucose concentration in serum was measured by a glucose oxidase method using a commercial kit. 2. Platelet-aggregating action Platelet samples were obtained from a healthy man and a male Japanese white rabbit. Namely, blood samples were obtained from the elbow vein of the man and from the auricle artery of the rabbit, and to the blood samples were added 0.31% and 0.38% of citric acid respectively. The blood samples were centrifuged to prepare platelet-rich plasma (PRP), and the PRP was used for the measurement in the platelet aggregation test, using a permeable platelet aggregation ability analyzer (AGGREGO-METER RAM-61; Rika Denki, Japan). As aggregation-inducing agents, ADP (adenosine diphosphate), arachidonic acid, collagen, a platelet activating factor, epinephrine and Ca** ionophore A-23187 were used. Each test compound was dissolved in DMSO (dimethylsulfoxide), and the solution was added to the PRP. 3. Action on hexobarbital sleep First, ddY male mice 5 weeks old were starved for 24 hours, then 70 mg/kg of hexobarbital was intraperitoneally administered to each mouse, and a time from the disappearance to the restoration of the body-righting reflex was considered the sleep time. A test compound was administered 30 minutes before the above administration. Results Compounds 1c, 2c, 3c, and 4c exhibited a significant blood sugar lowering activity and inhibition of platelet aggregating activity, at a dose of 10 mg/kg. On the other hand, the compound 2c did not exhibit a sleep-prolonging action at doses of both 10 mg/kg p.o., and 30 mg/kg p.o., revealing that it has low central side effects.

Claims: Claims for the following Contracting States : AT, BE, CH, DE, DK, FR, GB, IT, LI, LU, NL, SE A compound which is (i) a benzoxepin derivative of the formula in which R represents a pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, imidazolyl, furyl or thienyl group, or (ii) a salt thereof. A compound according to claim 1 in which R represents 2-pyridyl, 3-pyridyl, 4-pyridyl or pyrazinyl. A compound according to claim 1 or claim 2 which is a said salt, being an acid addition salt. A method of making a compound as defined in any one of claims 1 to 3, comprising the step of reducing an oxime of the formula wherein R has the same meaning as defined in claim 1, and hydrolysing the reduction product. A method according to claim 4 in which a compound of the formula wherein R has the same meaning as defined in claim 1, is cyclopropanated to form an oxabicycloheptane compound of the formula which is converted to an oxepin derivative of the formula which is converted to said oxime. A pharmaceutical preparation for lowering blood sugar level, comprising a compound according to any one of claims 1 to 3 and a pharmaceutically acceptable carrier. A pharmaceutical preparation for inhibiting platelet aggregation, comprising a compound according to any one of claims 1 to 3 and a pharmaceutically acceptable carrier. A compound according to any one of claims 1 to 3 for therapeutic use. Use of a compound according to any one of claims 1 to 3 in the preparation of a medicament for the treatment of Type II diabetes. Use of a compound according to any one of claims 1 to 3 in the preparation of a medicament for the lowering of blood sugar level or for inhibiting blood platelet aggregation. Claims for the following Contracting State : ES A method of preparing a compound which is (i) a benzoxepin derivative of the formula in which R represents a pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, imidazolyl, furyl or thienyl group, or (ii) a salt thereof, comprising reducing an oxime of the formula and hydrolysing the reduction product. A method according to claim 1 in which a compound of the formula wherein R has the same meaning as defined in claim 1, is cyclopropanated to form an oxabicycloheptane compound of the formula which is converted to an oxepin derivative of the formula which is converted to said oxime. A method according to claim 1 or claim 2, in which R represents 2-pyridyl, 3-pyridyl, 4-pyridyl or pyrazinyl. Use of a compound as defined in claim 1 or claim 3 in the preparation of a medicament for the treatment of Type II diabetes. Use of a compound as defined in claim 1 or claim 3 in the preparation of a medicament for the lowering of blood sugar level or for inhibiting platelet aggregation.

Inventors: SHIBATA MAKOTO, TATSUOKA TOSHIO, SHIBATA, MAKOTO, TATSUOKA, TOSHIO
Applicants: SUNTORY LTD, SUNTORY LIMITED
Application year: 1990
Main classification: C07D405
IPC codes: A61P25, A61K31, A61P3, A61P7, C07D405