HETEROCYCLIC COMPOUND AND CARDIOTONIC CONTAINING THE SAME AS ACTIVE INGREDIENT

Abstract: A heterocyclic compound represented by general formula (I), which has an excellent positive inotropic action as a cardiotonic and inhibits the rise of heart rate, and a cardiotonic containing the same as the active ingredient, wherein group A-E represents -S-CR₄R₅-, -CH₂-S-, -NH-CH₂- or -CH₂-CH₂-.

Description: TECHNICAL FIELD The present invention relates to heterocyclic compounds represented by the formula (I) or pharmaceutically acceptable acid addition salts thereof and cardiotonic agents containing the heterocyclic compounds as effective components: wherein R and R 1 represent hydrogen atom or lower alkyl group; R 2 and R 3 may be independently same or different and represent hydrogen atom, lower alkyl group, lower alkoxy group, trifluoromethyl group, halogen atom, nitro group, amino group, cyano group or hydroxyl group or R 2 and R 3 are joined to form methylenedioxy group or forms naphthalene; and A-E represents -CH 2 -S-, -NH-CH 2 - or -CH 2 CH 2 - wherein R 4 and R 5 represent hydrogen atom or lower alkyl group. Certain embodiments are subject of the dependent claims. BACKGROUND ART Compounds represented by the following formula (II) are known as heterocyclic compounds having cardiotonic activity and are disclosed for example in Japanese Patent Provisional Publication (Kokai) Nos. 57-2284 and 58-131981 and Japanese Patent Publication (Kokoku) No. 61-53350. wherein R 1 and A-E are as defined above. These known heterocyclic compounds having cardiotonic activities were clinically unfavorable since they have not so strong cardiotonic activities and increase heart rate. We, the inventors carried out studies to succeed in synthesizing novel heterocyclic compounds having excellent positive inotropic effect as cardiotonic agent and suppressing increase of heart rate, by modifying the pyridyl group in the compound of the formula (II), thus completing the present invention. More specifically, the present invention is directed to tetrahydropyridine derivatives represented by the above-mentioned formula (I) or pharmaceutically acceptable acid addition salts thereof and cardiotonic agents containing them as effective components. DISCLOSURE OF THE INVENTION The terms used for definition of letters in the above-mentioned formula by which the compounds of the present invention are represented are defined and exemplified in the following. The wording "lower" refers to a group having 1 to 6 carbon atoms unless otherwise indicated. The "lower alkyl group" refers to a straight- or branched-chain alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, n-hexyl or the like. The "lower alkoxy group" refers to a straight- or branched-chain alkoxy group such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, n-pentyloxy, n-hexyloxy or the like. The "halogen atom" may be fluorine, chlorine, bromine or iodine atom. The compound according to the present invention is for example as follows: 2-[1-[2-Hydroxy-2-phenylethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(2-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(3-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(2,4-dimethylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-isopropylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(4-Fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(3-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(2,4-Dichlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(3,4-Dichlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(2-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(3-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(2-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(3-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(2,5-dimethoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-[3,4-(methylenedioxy)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(2-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(3-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(4-Aminophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(4-Cyanophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-[2-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-[3-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4-methyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4-methyl-4H, 6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6,6-dimethyl-4H,6H-1,3,4-thiadiazin-5-one 6-Ethyl-2-[1-[2-hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6,6-dimethyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-ethyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-ethyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6,6-dimethyl-4H,6H-1,3,4-thiadiazin-5-one 6-Ethyl-2-[1-[2-hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Hydroxy-2-(4-nitrophenyl) ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Isopropoxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 2-[1-[2-Methoxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one 5-[1-(2-Hydroxy-2-phenylethyl)-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-(4-Fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-Hydroxy-2-(3-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-Hydroxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-(4-Cyanophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-Hydroxy-2-[3-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-Hydroxy-2-(2-naphthyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 5-[1-[2-Methoxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one 4,5-Dihydro-3-[1-(2-hydroxy-2-phenylethyl)-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 3-[1-[2-(4-Fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one 3-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-hydroxy-2-(4-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-hydroxy-2-[3,4-(methylenedioxy)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-hydroxy-2-(2-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-hydroxy-2-(3-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-hydroxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 3-[1-[2-(4-Cyanophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-hydroxy-2-[2-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 3-[1-[2-(4-Aminophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one 3-[1-[2-(4-Chlorophenyl)-2-methoxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one 4,5-Dihydro-3-[1-[2-methoxy-2-(4-nitrophenyl)ethyll-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one 4,5-Dihydro-6-[1-(2-hydroxy-2-phenylethyl)-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one 4,5-Dihydro-6-[1-[2-hydroxy-2-(2-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one 6-[1-[2-(4-Fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydropyridazin-3(2H)-one 6-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydropyridazin-3(2H)-one 4,5-Dihydro-6-[1-[2-hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one 4,5-Dihydro-6-[1-[2-hydroxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one 6-[1-[2-(4-Cyanophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydropyridazin-3(2H)-one 4,5-Dihydro-6-[1-[2-hydroxy-2-[2-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one 6-[1-[2-(4-Chlorophenyl)-2-methoxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydropyridazin-3(2H)-one Preferably, the group R 1 in the formula (I) is hydrogen atom and A-E is -S-CH 2 -, -CH 2 -S-, -NH-CH 2 - or -CH 2 CH 2 -. The compound of the present invention has asymmetric carbon atoms in its structure. It is to be understood that isomers due to such asymmetric carbon atom or combination (racemate) of any of the isomers are included in the category of the compound (I). The compounds of the present invention represented by the formula (I) may be prepared by, for example, the following procedure. The compound of the formula (II) was reacted with an equivalent mole or more of substituted or unsubstituted phenacyl bromide (compound of the formula III) in lower alcohol such as methanol, ethanol or isopropanol, dichloroethane or toluene at room temperature for one day or for 1 to 8 hours under reflux with heating to obtain pyridinium salt (hereinafter referred to as intermediate). This intermediate is a novel compound. The obtained intermediate, which is so pure as to be directly usable for a next process, may be further purified as needs demand by a normal purification method such as recrystallization from methanol, ethanol or absolute ethanol or column chromatography. The intermediate obtained in the above-mentioned process is dissolved in lower alcohol such as methanol, ethanol or isopropanol, water or mixture thereof and gradually added with equivalent to 15 fold molar amount of reducing agent such as sodium borohydride under cooling and then reacted at room temperature for 1 to 24 hours, thereby preparing the compound of the formula (I) according to the present invention (see the following reaction formulae). The compounds of the formula (I) where R is lower alkyl can be prepared by reacting the compound of the formula (I) where R is hydrogen atom as starting material in lower alcohol under the presence of strong acid such as concentrated sulfuric acid, concentrated hydrochloric acid, p-toluenesulfonic acid at room temperature to reflux for one to 8 hours. If necessary, such reaction may be carried out in a mixed solution added with benzene. The compounds of the present invention can be purified by the normal purification method such as that used for the above-mentioned intermediate. wherein R, R 1 , R 2 , R 3 and A-E are as defined above. According to the above-mentioned procedure, the compounds of the formula (I) are ordinary obtained as racemate which may be mechanically or chemically divided into optical antipodes thereof by known process. The compound of the formula (I) may be converted into a pharmaceutically acceptable salt by using an appropriate acid. The appropriate acids which can be used include, for example, inorganic acids such as hydrochloric, sulfuric, hydrobromic, nitric or phosphoric acid, and organic acids such as acetic, oxalic, propionic, glycolic, lactic, pyruvic, malonic, succinic, maleic, fumaric, malic, tartaric, citric, benzoic, cinnamic, methanesulfonic, benzenesulfonic, p-toluenesulfonic or salicylic acid. The compound of the formula (II) which is the starting material in the above-mentioned process is a known compound and can be prepared according to a process described in Japanese Patent Publication (Kokoku) No. 61-53350 or Japanese Patent Provisional Publication (Kokai) No. 57-2284 or 58-131981. The pharmacological effects of the compound of the present invention represented by the formula (I) will now be described: Nos. of the compounds in the pharmacological tests 1 and 2 correspond to those in Examples referred to hereinafter. Pharmacological Test 1 A heart was removed from a male Hartley guinea pig (having a body weight of about 400 g or so) and a right atrium and papillary muscles of a right ventricle were separated from the removed heart. These preparations were suspended in 15 ml of Magnus' bath under load of 0.5 g (papillary muscles) or 1.0 g (right atria). Contraction of papillary muscles upon electric stimulation (1 Hz, 5 msec, 1.5×threshold voltage) and spontaneous contraction of the right atria were recorded through a transducer (manufactured by Orientec, T7-8-240) by a polygraph system (manufactured by NIHONKOHDEN, RMP-6008 and WT-685G). Krebs-Henseleit solution was used as nutritive liquid bubbled with mixed gases of 95% O 2 with 5% CO 2 at 30°C. The samples were injected into bathes at a concentration of 3×10 -5 M. The obtained results are shown in Table 1. The value of inotropic effect is a percentage of increment of contractile force by samples when that by isoprotelenol (1 ×10 -8 M) is considered to be 100%. The value of chronotropic effect is a percentage of atrial rate after the injection of samples when the atrial rate before the injection is considered to be 100%. Compound No. Inotropic Effect Chronotropic Effect Compound No. Inotropic Effect Chronotropic Effect 1 55.7 87.6 43 57.2 85.2 7 54.0 95.2 44 39.9 100.8 8 50.4 89.0 45 99.5 79.1 12 51.0 93.8 46 61.9 81.6 13 72.2 93.4 47 81.4 78.2 14 26.3 73.5 48 45.4 77.7 17 45.0 85.8 49 27.7 87.6 18 52.2 97.8 50 38.9 98.6 20 65.7 87.5 51 36.8 91.4 21 92.6 84.5 53 102.9 87.8 22 30.4 76.7 54 25.2 97.3 25 58.5 65.2 57 46.8 94.9 27 63.1 98.7 60 43.8 92.6 29 79.3 101.1 64 23.8 93.0 30 113.9 100.4 69 28.6 79.7 31 74.7 90.4 70 56.0 99.2 32 63.9 93.1 71 25.3 98.7 34 49.9 98.1 a 22.2 158.8 35 63.5 90.7 b 36.2 116.9 39 28.3 75.7 c 7.3 110.0 40 35.3 98.1 d 4.6 112.0 42 71.0 85.9 (unit: %) As is clear from the above-mentioned test results, the compounds of the present invention selectively increase contractile force of cardiac muscles without increasing heart rate and therefore is useful as a cardiotonic agent for cure and prevention of acute and chronic heart failure. The compounds a to d in Table 1 are typical examples of the compounds of the formula (II) (the starting materials of the present invention) and are as follows: a: 2-(4-Pyridyl)-4H,6H-1,3,4-thiadiazin-5-one (typical compound disclosed in Japanese Patent Provisional Publication (Kokai) No. 58-131981) b: 5-(4-Pyridyl)-3H,6H-1,3,4-thiadiazin-2-one (typical compound disclosed in Japanese Patent Provisional Publication (Kokai) No. No.58-131981) c: 4,5-Dihydro-6-(4-pyridyl)-pyridazin-3(2H)one (typical compound disclosed in Japanese Patent Publication (Kokoku) No. 61-53350) d: 4,5-Dihydro-3-(4-pyridyl)-1,2,4-triazin-6(1H)-one (typical compounds disclosed in Japanese Patent Provisional Publication (Kokai) No. 58-131981) Pharmacological Test 2 The acute toxicity was determined by administrating the sample compound, which was dissolved by physiological saline solution, in the tail vein of ddY mice (5-weeks-old, having a body weight of 25 to 28 g) and LD 50 was obtained by the up-and-down method. The obtained results are shown in Table 2. Compound Acute Toxicity (mg/kg) hydrochloride of compound 13 101 hydrochloride of compound 20 173 hydrochloride of compound 21 226 hydrochloride of compound 25 135 hydrochloride of compound 30 160 hydrochloride of compound 35 226 hydrochloride of compound 60 226 The compounds of the present invention may be administered to human orally or subcutaneous, intramuscular or intravenous injection or other methods. In oral administration, the compounds may be in the form of solids such as tablets, granules, powders, capsules or the like which may contain pharmaceutically acceptable additives such as binders, extenders and disintegrators and so on, e.g., saccharides and cellulose preparations. When used as liquids for oral administration, they may be in the form of mixture for internal use, suspensions, emulsions, syrups and so on. Alternatively, they may be in the forms of freeze-dried products which are to be dissolved upon use. In injection, the compounds may be in the form of aqueous liquid, suspensions, oily or water-soluble emulsions which are usually prepared by dissolving or suspending the compounds in solvent such as sterile distilled water or physiological saline solution and which may be added with usually used solubilizers, stabilizers, preservatives and isotonicities as needs demand. Although the daily doses of these compounds may be varied according to the conditions, ages or weights of the subjects to be treated, the daily doses to adult humans (weights: 60 kg) may fall within the range of 6-600 mg and may be divided into two or three portions. BEST MODE FOR CARRYING OUT THE INVENTION [Preparations and Examples] The present invention is more specifically illustrated with reference to the following preparations and examples. It is to be, however, noted that the present invention is not limited to the preparations and examples. Preparation 1: Preparation of 1-[(4-methoxyphenyl)carbonylmethyl]-4-(4H,6H-1,3,4-thiadiazin-5-one-2-yl)pyridinium bromide (Intermediate 1) 2-(4-Pyridyl)-4H,6H-1,3,4-thiadiazin-5-one (1.88 g, 9.74 mmol) and 4'-methoxyphenacyl bromide (2.23 g, 9.74 mmol) were dissolved in absolute ethanol (40 ml) and stirred at room temperature for one day. The resulting precipitate was collected by filtration and washed with absolute ethanol to obtain the titled compound (3.84g) as yellow powder. Yield: 93% Melting Point: 174-178°C (dec.) In accordance with the procedure of the Preparation 1, the intermediates of the formula IV shown in Tables 3 and 4 were obtained from corresponding starting materials. Preparation 2: Preparation of 1-[(4-methoxyphenyl)carbonylmethyl]-4-(3H,6H-1,3,4-thiadiazin-2-one-5-yl)pyridinium bromide (Intermediate 39) 5-(4-Pyridyl)-3H,6H-1,3,4-thiadiazin-2-one (386 mg, 2 mmol) and 4'-methoxyphenacyl bromide (550 mg, 2.4 mmol) were dissolved in absolute ethanol (6 ml), refluxed for three hours and then stirred at room temperature overnight. The resulting precipitate was collected by filtration and washed with absolute ethanol to obtain the titled compound (814 mg) as light brown powder. Yield: 96.4% Melting Point: 223.5-224°C (dec.) In accordance with the procedure of the Preparation 2, the intermediates of the formula IV shown in Table 5 were obtained from corresponding starting materials. Preparation 3: Preparation of 1-[(4-methoxyphenyl)carbonylmethyl]-4-(4,5-dihydropyridazin-3(2H)-one-6-yl)pyridinium bromide (Intermediate 49) 4,5-Dihydro-6-(4-pyridyl)-pyridazin-3(2H)-one (175 mg, 1 mmol) and 4'-methoxyphenacyl bromide (252 mg, 1.1 mmol) were dissolved in absolute ethanol (5 ml), refluxed for two hours and then stirred at room temperature overnight. The resulting precipitate was collected by filtration and washed with absolute ethanol to obtain the titled compound (350 mg) as brown columns. Yield: 87% Melting Point: 250-255°C (dec.) In accordance with the procedure of the Preparation 3, intermediates of the formula IV shown in Table 6 were obtained from corresponding starting materials. Preparation 4: 1-[(4-Methoxyphenyl)carbonylmethyl]-4-(4,5-dihydro-1,2,4-triazin-6(1H)-one-3-yl)pyridinium bromide (Intermediate 56) 4,5-Dihydro-3-(4-pyridyl)-1,2,4-triazin-6(1H)-one (176 mg, 1 mmol) and 4'-methoxyphenacyl bromide (252 mg, 1.1 mmol) were dissolved in absolute ethanol (5 ml), refluxed for two hours and then stirred at room temperature for one day. The resulting precipitate was collected by filtration and washed with absolute ethanol to obtain the titled compound (374 mg) as yellow-brown powder. Yield: 92% Melting Point: 220-225°C (dec.) In accordance with the procedure of the Preparation 4, intermediates of the formula IV shown in Table 7 were obtained from corresponding starting materials. Example 1: 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 1) 1-[(4-Methoxyphenyl)carbonylmethyl]-4-(4H,6H-1,3,4-thiadiazin-5-one-2-yl)pyridinium bromide (3.84 g, 9.09 mmol) was dissolved in methanol-water (1:1 v/v %) (50 ml), gradually added with sodium borohydride (3.43 g, 90.9 mmol) under ice cooling and then stirred at room temperature overnight. The solvent was removed under reduced pressure. The residue was added with dichloromethane, then washed with water and dried over anhydrous magnesium sulfate. The solvent was removed to obtain the titled compound (2.44 g) as white crystals. Yield: 70% Melting Point: 197-198°C (recrystallization from acetone-methanol) IR(KBr)cm -1 : 3454, 3217, 3096, 1671 NMR(CDCl 3 -DMSO-d 6 )δ: 2.50-2.70(6H, m), 3.20-3.50(2H, m), 3.29(2H, s), 3.80(3H, s), 4.15(1H, brs), 4.75(1H, m), 6.45(1H, s), 6.87(2H, d, J=8Hz), 7.30(2H, d, J=8Hz), 10.75(1H,s) MS m/z: 347(M + ) In accordance with the procedure of the Example 1, the following compounds were obtained from corresponding starting materials. 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 3) Yield: 74.2% Appearance: colorless needles (recrystallization from ethanol) Melting Point: 182.5-184.5°C IR(KBr)cm -1 : 3196, 3099, 1672 NMR(DMSO-d 6 )δ : 1.28(3H, d, J=7Hz), 2.40(2H, s), 2.44-2.65(4H, m), 3.22(2H, s), 3.59(1H, q, J=7 Hz), 3.73(3H, s), 4.68(1H, m), 4.92(1H, d, J=3.7Hz), 6.38(1H, s), 6.86(2H, d, J=8.8Hz), 7.26(2H, d, J=8.8Hz), 11.37(1H, s) MS m/z: 361(M + ) 6-Ethyl-2-[1-[2-hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 4) Yield: 59.2% Appearance: opaline needles (recrystallization from ethanol) Melting Point: 148-149 o C (dec.) IR(KBr)cm -1 : 3188, 3104, 1664, 1612 NMR(DMSO-d 6 )δ: 0.94(3H, t, J=7.3Hz), 1.43(1H, m), 1.69(1H, m), 2.35-2.64(6H, m), 3.22(2H, s), 3.45(1H, m), 3.73 (3H, s), 4.69(1H, m), 4.94(1H, d, J=3.7Hz), 6.41(1H,s), 6.87(2H, d, J=8.4Hz), 7.26(2H, d, J=8.4Hz), 11.39(1H, s) MS m/z: 375(M + ) 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6,6-dimethyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 5) Yield: 46.5% Appearance: light yellow-brown granules (recrystallization from ethanol) Melting Point: 179.5-181.5°C (dec.) IR(KBr)cm -1 : 3231, 3196, 3091, 1658 NMR(DMSO-d 6 )δ: 1.32(6H, s) 2.40(2H, s), 2.43-2.67(4H, m), 3.22(2H, s), 3.73(3H, s), 4.68(1H, m), 4.95(1H, d, J=4Hz), 6.35(1H, s), 6.87(2H, d, J=8.4Hz), 7.23(2H, d,J=8.4Hz), 11.38(1H, s) MS m/z: 375(M + ) 2-[1- (2-Hydroxy-2-phenylethyl)-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 2) Yield: 77.8% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 179.5-181.5 o C (dec.) IR(KBr)cm -1 : 3176, 3085, 3018, 1666 NMR(DMSO-d 6 )δ: 2.39(2H, s), 2.47-2.68(4H, m), 3.24(2H, d, J=2.9Hz), 3.41 (2H, s), 4.74(1H, m), 5.05(1H, d, J=3.7Hz), 6.40(1H, s), 7.20-7.36(5H, m), 11.37(1H, s) MS m/z: 317(M + ) 2-[1-[2-Hydroxy-2-(2-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 6) Yield: 78% Appearance: white powder (recrystallization from chloroform-methanol) Melting Point: 194-196°C (dec.) IR(KBr)cm -1 : 3443, 3167, 3079, 3008, 1671 NMR(DMSO-d 6 )δ: 2.40(2H, s), 2.40-2.55(2H, m), 2.66(2H, s), 3.15-3.35(2H, m), 3.41(2H, s), 3.78(3H, s), 4.91(1H, d, J=4.4Hz), 5.08(1H, brs), 6.42(1H, s), 6.90-6.95(2H, m), 7.20(1H, t, J=6.2Hz), 7.42(1H, d, J=6.2Hz), 11.39(1H, s) MS m/z: 347(M + ) 2-[1-[2-Hydroxy-2-(3-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 7) Yield: 59% Appearance: white powder (recrystallization from dichloromethane-hexane) Melting Point: 152-153°C (dec.) IR(KBr)cm -1 : 3178, 3087, 3016, 1667 NMR(DMSO-d 6 )δ: 2.38(2H, s), 2.51-2.66(4H, m), 3.23(2H, s), 3.41(2H, s), 3.73(3H, s), 4.71(1H, brs), 5.05(1H, d, J=4Hz), 6.40(1H, s), 6.78(1H, d, J=7.3Hz), 6.91(2H, s+d, J=7.3Hz), 7.21(1H, m), 11.37(1H, s) MS m/z: 347(M + ) 2-[1-[2-Hydroxy-2-(2,5-dimethoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 8) Yield: 82% Appearance: light yellow powder (recrystallization from dichloromethane- hexane) Melting Point: 176-178°C (dec.) IR(KBr)cm -1 : 3182, 3095, 1670 NMR(CDCl 3 )δ: 2.50-2.95(6H, m), 3.15-3.50(2H, m), 3.31(2H, s), 3.80(6H, s), 3.85(1H, brs), 5.15(1H, m), 6.50(1H, s), 6.80(2H, ABq, J=9Hz), 7.15(1H, s), 9.05(1H, s) MS m/z: 377(M + ) 2-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 9) Yield: 76% Appearance: light pink powder (recrystallization from chloroform-methanol) Melting Point: 193-195°C (dec.) IR(KBr)cm -1 : 3433, 3168, 3075, 3009, 1664 NMR(DMSO-d 6 )δ: 2.40(2H, s), 2.52-2.54(2H, m), 2.68(2H, m), 3.20-3.30 (2H, m), 3.41(2H, s), 5.10(1H, brs), 5.33(1H, d, J=4.4Hz), 6.42(1H, s), 7.25-7.29(1H, m), 7.34-7.38(2H, m), 7.60(1H, d, J=5.9Hz), 11.38(1H, s) MS m/z: 352(M + ) 2-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-ethyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 11) Yield: 89.3% Appearance: white powder (recrystallization from ethanol) Melting Point: 154.5-156.5°C (dec.) IR(KBr)cm -1 : 3202, 1674 NMR(DMSO-d 6 )δ: 0.94(3H, t, J=7.3Hz), 1.43(1H, m), 1.70(1H, m), 2.30-2.74(6H, m), 3.27(2H, m), 3.46(1H, m), 5.12 (1H, m), 5.33(1H, d, J=4Hz), 6.42(1H s), 7.24-7.61(4H,m), 11.39(1H, s) MS m/z: 379(M + ) 2-[1-[2-(3-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 12) Yield: 70% Appearance: yellow powder (recrystallization from chloroform) Melting Point: 195-198 o C (dec.) IR(KBr)cm -1 : 3459, 3179, 3080, 1659 NMR(DMSO-d 6 )δ: 2.37(2H, s), 2.51-2.70(2H, m), 3.23(2H, s), 4.77(1H, brs), 5.26(1H, d, J=4.4Hz), 6.40(1H, s), 7.26-7.36(4H, m), 7.40(1H, s), 11.39(1H, s) MS m/z: 351(M + ) 2-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 13) Yield: 70% Appearance: yellow powder (recrystallization from tetrahydrofuran) Melting Point: 218-220 o C (dec.) IR(KBr)cm -1 : 3449, 3179, 3079, 1660 NMR(DMSO-d 6 )δ: 2.38(2H, brs), 2.56-2.75(4H, m), 3.22(2H,s), 3.41(2H, s), 4.75-4.80(1H, brs), 5.20(1H, d, J=4Hz), 6.39(1H, s), 7.36(4H, ABq, J=9Hz), 11.37(1H, s) MS m/z: 351(M + ) 2-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 14) Yield: 90.9% Appearance: opaline particles (recrystallization from ethanol) Melting Point: 179.5-180.5 o C (dec.) IR(KBr)cm -1 : 3359, 3063, 3018, 1662 NMR(DMSO-d 6 )δ: 1.27(3H, d, J=7Hz), 2.39(2H, s), 2.46-2.69(4H, m), 3.22(2H, s), 3.60(1H, q, J=7Hz), 4.74(1H,m), 5.18(1H, d, J=4Hz), 6.39(1H, s), 7.33-7.39(4H, m), 11.38(1H, s) MS m/z: 365(M + ) 2-[1-[2-(4-Chlorophenyl) -2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-ethyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 15) Yield: 90% Appearance: opaline plates (recrystallization from ethanol) Melting Point: 150.5-153.5°C (dec.) IR(KBr)cm -1 : 3190, 3089, 1668 NMR(DMSO-d 6 )δ: 0.94(3H, t, J=7.3Hz), 1.43(1H, m), 1.69(1H, m), 2.31-2.67(6H, m), 3.22(2H, s), 3.45(1H, m), 4.74 (1H, m), 5.18(1H, d, J=4Hz), 6.40(1H, s), 7.33-7.39(4H, m), 11.38(1H, s) MS m/z: 379(M + ) 2-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6,6-dimethyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 16) Yield: 78.7% Appearance: yellow powder (recrystallization from ethanol) Melting Point: 190-192.5°C (dec.) IR(KBr)cm -1 : 3454, 3237, 3089, 1655 NMR(DMSO-d 6 )δ: 1.33(6H, s), 2.39(2H, s), 2.46-2.69(4H, m), 3.21(2H, s), 4.74(1H, m), 5.18(1H, d, J=4Hz), 6.35(1H, s), 7.33-7.39(4H, m), 11.37(1H, s) MS m/z: 379(M + ) 2-[1-[2-(2,4-Dichlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 17) Yield: 64% Appearance: yellow powder (recrystallization from chloroform) Melting Point: 198-201°C (dec.) IR(KBr)cm -1 : 3182, 3095, 3008, 1671 NMR(DMSO-d 6 )δ: 2.39(2H, s), 2.51-2.55(2H, m), 2.67(2H, m), 3.23-3.30 (2H, m), 3.41(2H, s), 5.08(1H, brs), 5.47(1H, d, J=4.4Hz), 6.41(1H, brs), 7.44(1H, d, J=8.4Hz), 7.53(1H, s), 7.60(1H, d, J=8.4Hz), 11.39(1H, s) MS m/z: 385(M + ) 2-[1-[2-(3,4-Dichlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 18) Yield: 51% Appearance: yellow powder (recrystallization from chloroform-methanol) Melting Point: 204-207°C (dec.) IR(KBr)cm -1 : 3446, 3175, 3075, 1656 NMR(DMSO-d 6 )δ: 2.37(2H, s), 2.52-2.67(4H, m), 3.22(2H, s), 3.41(2H, s), 4.76(1H, brs), 5.35(1H, s), 7.34(1H, d,J=8.4Hz), 7.58(2H, dd, J=1.8Hz, 8.4Hz), 11.37(1H, s) MS m/z: 385(M + ) 2-[1-[2-Hydroxy-2-(2-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 19) Yield: 73% Appearance: white powder (recrystallization from chloroform-methanol) Melting Point: 180-182°C (dec.) IR(KBr)cm -1 : 3197, 3111, 1676 NMR(DMSO-d 6 )δ: 2.29(3H, s), 2.40-2.60(4H, m), 2.65-2.67(2H, m), 3.20-3.30(2H, m), 3.41(2H, s), 4.97(2H, m), 6.41 (1H, s), 7.10-7.25(3H, m), 7.45(1H, d, J=7.3Hz), 11.39 (1H, s) MS m/z: 331(M + ) 2-[1-[2-Hydroxy-2-(3-methylphenyl) ethyl]-1,2,5,6-tetrahydropyrid-4- yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 20) Yield: 70% Appearance: white powder (recrystallization from dichloromethane-methanol) Melting Point: 183-184°C (dec.) IR(KBr)cm -1 : 3458, 3176, 3076, 1663 NMR(CDCl 3 -DMSO-d 6 )δ: 2.35(3H, s), 2.60-2.70(5H, m), 2.90-3.00(1H, m), 3.20-3.30(2H+2H, m+s), 4.00(1H, brs), 4.77 (1H, t, J=6.8Hz), 6.46(1H, s), 7.07-7.24(4H, m), 9.92(1H, s) MS m/z: 331(M + ) 2-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 21) Yield: 33% Appearance: white powder (recrystallization from tetrahydrofuran) Melting Point: 205-208°C (dec.) IR(KBr)cm -1 : 3453, 3179, 3080, 1663 NMR(DMSO-d 6 )δ: 2.27(3H, s), 2.73(2H, s), 2.55-2.65(4H, m), 3.22(2H, s) 3.40(2H, s), 4.69(1H, brs), 4.97(1H, d,J=3.7Hz), 6.39(1H, s), 7.11(2H, d, J=8Hz), 7.22(2H, d, J=8Hz), 11.38(1H, s) MS m/z: 331(M + ) 2-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 22) Yield: 78.5% Appearance: white powder (recrystallization from ethanol) Melting Point: 174.5-176.5°C (dec.) IR(KBr)cm -1 : 3191, 3090, 1671 NMR(DMSO-d 6 )δ: 1.27(3H, d, J=7Hz), 2.27(3H, s), 2.39 (2H, s), 2.45-2.65(4H, m), 3.22(2H, s), 3.60(1H, q, J=7Hz), 4.69(1H, m), 4.95(1H, d, J=3.7Hz), 6.38(1H, s), 7.11(2H, d, J=8.1Hz), 7.22(2H d, J=8.1Hz), 11.37(1H, s) MS m/z: 345(M + ) 6-Ethyl-2-[1-[2-hydroxy-2-(4-methylphenyl) ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 23) Yield: 80.2% Appearance: white prisms (recrystallization from ethanol) Melting Point: 160-162°C (dec.) IR(KBr)cm -1 : 3189, 3086, 1633 NMR(DMSO-d 6 )δ: 0.94(3H, t, J=7.3Hz), 1.43(1H, m), 1.69(1H, m), 2.28(3H, s), 2.35-2.67(6H, m), 3.23(2H, s), 3.45(1H, m), 4.69(1H, m), 4.96(1H, d, J=4Hz), 6.41(1H, s), 7.11(2H, d, J=8.1Hz), 7.22(2H, d, J=8.1Hz), 11.38(1H,s) MS m/z: 359(M + ) 2-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6,6-dimethyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 24) Yield: 47.7% Appearance: light yellow plates (recrystallization from ethanol) Melting Point: 182-184°C (dec.) IR(KBr)cm -1 : 3235, 3198, 3089, 1656 NMR(DMSO-d 6 )δ: 1.33(6H, s), 2.27(3H, s), 2.40(2H, s), 2.44-2.66(4H, m), 3.22(2H, s), 4.70(1H, m), 4.98(1H, d, J=3.7Hz), 6.35(1H, s), 7.11(2H, d, J=8.1Hz), 7.22(2H, d,J=8.1Hz), 11.38(1H, s) MS m/z: 359(M + ) 2-[1-[2-Hydroxy-2-(2,4-dimethylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 25) Yield: 49% Appearance: white powder (recrystallization from methanol) Melting Point: 178-182°C (dec.) IR(KBr)cm -1 : 3191, 3109, 1675 NMR(DMSO-d 6 )δ: 2.23(3H, s), 2.25(3H, s), 2.35-2.45(4H, m), 2.60-2.70 (2H, m), 3.20-3.30(2H, m), 3.36(2H, s), 4.90-4.95(2H, m), 6.91(1H, s), 6.97(1H, d, J=7.9Hz), 7.32(1H, d, J=7.9Hz), 11.39(1H, s) MS m/z: 345(M + ) 2-[1-[2-Hydroxy-2-(2-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 26) Yield: 51% Appearance: light pink powder (recrystallization from chloroform) Melting Point: 193-195°C (dec.) IR(KBr)cm -1 : 3176, 3063, 3007, 1643 NMR(DMSO-d 6 )δ: 2.42(2H, s), 2.51-2.60(2H, m), 2.68-2.70(2H, m), 3.29(2H, s), 3.42(2H, s), 5.00-5.10(2H, m), 6.42(1H, s), 6.75-6.85(2H, m), 7.05-7.10(1H, m), 7.31-7.33(1H, m), 10.10(1H, brs), 11.40(1H, s) MS m/z: 333(M + ) 2-[1-[2-Hydroxy-2-(3-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 27) Yield: 48% Appearance: white powder (recrystallization from chloroform) Melting Point: 148-150°C (dec.) IR(KBr)cm -1 : 3179, 1662, 1602 NMR(DMSO-d 6 )δ: 2.38(2H, s), 2.50-2.70(4H, m), 3.23(2H, s), 3.41(2H, s), 4.65(1H, brs), 4.98(1H, d, J=3.6Hz), 6.40(1H, s), 6.60(1H, d, J=8Hz), 6.73-6.77(2H, m), 7.08(1H, t J=7.7Hz), 9.25(1H, s), 11.38(1H, s) MS m/z: 333(M + ) 2-[1-[2-Hydroxy-2-(2-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 29) Yield: 58% Appearance: yellow powder (recrystallization from ethanol) Melting Point: 207-210°C (dec.) IR(KBr)cm -1 : 3217, 1674 NMR(DMSO-d 6 )δ: 2.37(2H, s), 2.54-2.70(4H, m), 3.18(2H, s), 3.41(2H, s), 5.31(1H, brs), 5.54(1H, d, J=4.4Hz), 6.38(1H, s), 7.50(1H, m), 7.72(1H, m), 7.85-7.90(2H, m),11.38(1H, s) MS m/z: 362(M + ) 2-[1-[2-Hydroxy-2-(3-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 30) Yield: 66% Appearance: yellow powder (recrystallization from chloroform-methanol) Melting Point: 200-202°C (dec.) IR(KBr)cm -1 : 3445, 3178, 3080, 1654 NMR(DMSO-d 6 )δ: 2.37(2H, s), 2.50-2.80(4H, m), 3.15-3.30(2H, m), 3.41(2H, s), 4.90(1H, brs), 5.50(1H, d, J=4.4 Hz), 6.39(1H, s), 7.61(1H, t, J=8Hz), 7.81(1H, d, J=8Hz), 8.10(1H, d, J=8Hz), 8.23(1H, s), 11.38(1H, s) MS m/z: 362 (M + ) · 2-[1-[2-Hydroxy-2-[3,4-(methylenedioxy)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 32) Yield: 58% Appearance: light yellow powder (recrystallization from dichloromethanemethanol) Melting Point: 180-183°C (dec.) IR(KBr)cm -1 : 3243, 1662 NMR(CDCl 3 -DMSO-d 6 )δ: 2.50-2.70(5H, m), 2.80-2.90(1H, m), 3.15-3.45(2H+2H, m), 4.06(1H, s), 4.71(1H, t J=6.8Hz), 5.95(2H, s), 6.45(1H, s), 6.77-6.83(2H, m), 6.90(1H, m),10.37(1H, s) MS m/z: 361(M + ) 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4-methyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 37) Yield: 80% Appearance: yellow powder (recrystallization from chloroform-methanol) Melting Point: 135-137°C (dec.) IR(KBr)cm -1 : 1660 NMR(CDCl 3 )δ: 2.55-2.70(5H, m), 2.90-3.00(1H, m), 3.25- 3.50(2H, m), 3.30(2H, m), 3.45(3H, s), 3.80(3H, s), 3.84(1H, d, J=4.3Hz), 4.74(1H, t, J=6.9Hz), 6.46(1H, s), 6.89(2H, d, J=8.6Hz), 7.30(2H, d, J=8.6Hz) MS m/z: 361(M + ) 2-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4-methyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 38) Yield: 72% Appearance: yellow powder (recrystallization from dichloromethanediethyl ether) Melting Point: 147-150°C (dec.) IR(KBr)cm -1 : 3160, 1660 NMR(CDCl 3 )δ: 2.40-3.00(6H, m), 3.31(2H, s), 3.46(2H, s), 3.23-3.60(2H, m), 3.92(1H, brs), 5.22(1H, d, J=4.2Hz), 6.47(1H, s), 7.20-7.40(3H, m), 7.68(1H, d, J=7.2Hz) MS m/z: 365(M + ) 2-[1-[2-Hydroxy-2-[2-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 33) Yield: 60% Appearance: light yellow powder (recrystallization from chloroform-methanol) Melting Point: 205-210°C (dec.) IR(KBr)cm -1 : 3191, 3088, 1661 NMR(DMSO-d 6 )δ: 2.40-2.55(3H, m), 2.60-2.70(3H, m), 3.20-3.30(2H, m), 3.41(2H, s), 5.08(1H, brs), 5.41(1H, d, J=4Hz), 6.42(1H, s), 7.46(1H, t, J=7.9Hz), 7.65-7.75(2H, m), 7.81(1H, d, J=7.9Hz), 11.38(1H, s) MS m/z: 385(M + ) 2-[1-[2-(4-Fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 35) Yield: 54% Appearance: white powder (recrystallization from chloroform-methanol) Melting Point: 185-190°C (dec.) IR(KBr)cm -1 : 3171, 3089, 1665 NMR(DMSO-d 6 )δ: 2.37(2H, s), 2.51-2.67(4H, m), 3.22(2H, s), 3.41(2H, s), 4.74(1H, brs), 5.14(1H, d, J=4Hz), 6.39(1H, s), 7.10-7.15(2H, m), 7.40-7.45(2H, m), 11.38(1H, s) MS m/z: 335(M + ) 2-[1-[2-(4-Aminophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 63) Yield: 8.5% Appearance: light yellow-white granules (recrystallization from ethanol) Melting Point: 183.0-183.5°C (dec.) IR(KBr)cm- 1 : 3428, 3341, 3231, 3004, 1662, 1615 NMR(DMS0-d 6 )δ: 2.37-2.63(6H, m), 3.21(2H, s), 3.40(2H, s), 4.55(1H, m), 4.67(1H, d, J=3.3Hz), 4.88(2H, s), 6.40(1H, s), 6.50(2H, d, J=8.4Hz), 6.98(2H, d, J=8.4Hz), 11.36(1H, s) MS m/z: 332(M + ) Example 2: 5-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 39) 1-[(4-Methoxyphenyl)carbonylmethyl]-4-(3H,6H-1,3,4-thiadiazin-2-one-5-yl)pyridinium bromide (760 mg, 1.8 mmol) was dissolved in methanol (8 ml) and gradually added with sodium borohydride (680 mg, 18 mmol) under ice-cooling and then stirred at room temperature overnight. The solvent was removed under reduced pressure. The residue obtained was added with dichloromethane, washed with water and dried over anhydrous magnesium sulfate. The residue obtained by evaporation was purified by column chromatography (dichloromethane-methanol=20:1) to obtain the titled compound (423 mg) as white crystals. Yield: 67.7% Melting Point: 191.5°C (dec.) (recrystallization from ethanol) IR(KBr)cm -1 : 3345, 3022, 1635 NMR(DMSO-d 6 )δ: 2.35(2H, s), 2.44-2.64(4H, m), 3.23(2H, s), 3.73(3H, s), 3.92(2H, s), 4.69(1H, m), 4.93(1H, d, J=4Hz), 6.41(1H, s), 6.87 (2H, d, J=8.8Hz), 7.26(2H, d, J=8.8Hz), 11.36(1H, s) MS m/z: 347(M + ) In accordance with the procedure of Example 2, the following compounds were obtained from corresponding starting materials. 5-[1-(2-Hydroxy-2-phenylethyl)-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 40) Yield: 81.1% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 177.5-178°C (dec.) IR(KBr)cm -1 : 3168, 3076, 1642 NMR(DMSO-d 6 )δ: 2.35(2H, s), 2.48-2.68(4H, m), 3.24(2H, d, J=2.9Hz), 3.92(2H, s), 4.75(1H, m), 5.05(1H, d, J=4Hz),6.41(1H, s), 7.20-7.36(5H, m), 11.37(1H, s) MS m/z: 317(M + ) 5-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 41) Yield: 97.9% Appearance: brown granules (recrystallization from ethanol) Melting Point: 181.5-182.0°C (dec.) IR(KBr)cm -1 : 3210, 3067, 1637 NMR(DMSO-d 6 )δ: 2.37(2H, s), 2.53-2.69(4H, m), 3.27(2H, m), 3.93(2H, s), 5.13(1H, m), 5.32(1H, d, J=4.4Hz), 6.42(1H, s), 7.24-7.62(4H, m), 11.37(1H, s) MS m/z: 351(M + ) 5-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 42) Yield: 84.7% Appearance: colorless micaceous crystals (recrystallization from ethanol) Melting Point: 187-188°C (dec.) IR(KBr)cm -1 : 3505, 3202, 3056, 1633 NMR(DMSO-d 6 )δ: 2.42(2H, s), 2.47-2.68(4H, m), 3.22(2H, s), 3.92(2H, s), 4.75(1H, m), 4.77(1H, d, J=4.8Hz), 6.40(1H, s), 7.34-7.39(4H, m), 11.36 (1H, s) MS m/z: 351(M + ) 5-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 43) Yield: 81.3% Appearance: white fine needles (recrystallization from ethanol) Melting Point: 176-176.5°C(dec.) IR(KBr)cm -1 : 3194, 3063, 1645 NMR(DMSO-d 6 )δ: 2.27(3H, s), 2.35(2H, s), 2.45-2.64(4H, m), 3.23(2H, s), 3.92(2H, s), 4.70(1H, m), 4.95(1H, d, J=4Hz), 6.41(1H, s), 7.11(2H, d, J=8.1Hz), 7.23(2H, d, J=8.1Hz), 11.36(1H, s) MS m/z: 331(M + ) 5-[1-[2-Hydroxy-2-(3-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 44) Yield: 80.3% Appearance: opaline prisms (recrystallization from ethanol) Melting Point: 188.5-189°C (dec.) IR(KBr)cm -1 : 3261, 3057, 1629 NMR(DMSO-d 6 )δ: 2.36(2H, s), 2.45-2.66(4H, m), 3.23(2H, s), 3.92(2H, s),4.66(1H, m), 4.95(1H, d, J=3.7Hz), 6.41(1H, s), 6.59-7.10(4H, m), 9.22(1H, s), 11.36(1H, s) MS m/z: 333(M + ) 5-[1-[2-(4-Fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 46) Yield: 80.5% Appearance: colorless micaceous crystals (recrystallization from ethanol) Melting Point: 184.5-185.5°C (dec.) IR(KBr)cm -1 : 3507, 3198, 3058, 1635 NMR(DMSO-d 6 )δ: 2.34(2H, s), 2.46-2.70(4H, m), 3.22(2H, s), 3.92(2H, s), 4.75(1H, m), 5.11(1H, d, J=3.7Hz), 6.41(1H, s), 7.12(2H, dd, J=2.7Hz, 5.9Hz), 7.38(2H, dd, J=2.7Hz, 5.9Hz), 11.36(1H, s) MS m/z: 335(M + ) 5-[1-[2-Hydroxy-2-(2-naphthyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 69) Yield: 81.9% Appearance: opaline powder (recrystallization from DMF) Melting Point: 189.5-191°C (dec.) IR(KBr)cm -1 : 3355, 3199, 3054, 1654, 1636 NMR(DMSO-d 6 )δ: 2.36(2H, s), 2.60-2.74(4H, m), 3.27(2H, s), 3.92(2H, s), 4.93(1H, m), 5.22(1H, d, J=4.0Hz), 6.41(1H, s), 7.44-7.55(3H, m), 7.84-7.96(4H, m), 11.37(1H, s) MS m/z: 367(M + ) Example 3: 4,5-Dihydro-6-[1-[2-hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one (Compound 49) 1-[(4-Methoxyphenyl)carbonylmethyl]-4-(4,5-dihydropyridazin-3(2H)-one-6-yl)pyridinium bromide (300mg, 0.74mmol) was dissolved in methanol (5ml), gradually added with sodium borohydride (280 mg, 7.4 mmol) under ice cooling and then stirred at room temperature overnight. The solvent was removed under reduced pressure. The residue obtained was added with dichloromethane, washed with water and dried over anhydrous magnesium sulfate. The solvent was removed to obtain the titled compound (145 mg) as colorless crystals. Yield: 60% Melting Point: 187-189°C (dec.) (recrystallization from ethanol) IR(KBr)cm -1 : 3304, 1678, 1657 NMR(CDCl 3 )δ: 2.47-2.93(6H, m), 3.21(1H, d, J=16Hz), 3.44 (1H, d, J=16Hz), 3.81(1H, s), 4.75(1H, m), 6.16(1H,brs), 6.89(2H, d, J=8.5Hz), 7.31(2H, d, J=8.5Hz), 8.41(1H, s) MS m/z: 329(M + ) In accordance with the procedure of Example 3, the following compounds were obtained from corresponding starting materials. 6-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydropyridazin-3(2H)-one (Compound 50) Yield: 90% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 195-202°C (dec.) IR(KBr)cm -1 : 3231, 3134, 3066, 1686 NMR(CDCl 3 )δ: 2.39-2.98(10H, m), 3.24(1H, d, J=18Hz), 3.47(1H, d, J=18Hz), 3.95(1H, br), 5.22(1H, dd, J=2Hz, 10Hz), 6.16(1H, brs), 7.18-7.34 (3H, m), 7.68(1H, d, J=7Hz), 8.50(1H, s) MS m/z: 333(M + ) 6-[1-[2-(4-Fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydropyridazin-3(2H)-one (Compound 51) Yield: 78% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 172-180°C (dec.) IR(KBr)cm -1 : 3358, 3058, 1673 NMR(CDCl 3 )δ: 2.47-2.96(10H, m), 3.21(1H, d, J=18Hz), 3.44(1H, d, J=18Hz), 3.95(1H, br), 4.77(1H, m), 6.15(1H,brs), 7.04(2H, m), 7.35(2H, m), 8.43(1H, s) MS m/z: 317(M + ) 4,5-Dihydro-6-[1-[2-hydroxy-2-(2-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one (Compound 52) Yield: 76% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 181-188°C (dec.) IR(KBr)cm -1 : 3226, 3134, 3071, 1685 NMR(CDCl 3 )δ: 2.34(3H, s), 2.50-2.95(10H, m), 3.24(1H, d,J=18Hz), 3.46 (1H, d, J=18Hz), 3.84(1H, br), 5.06(1H, m), 6.16(1H, brs), 7.11-7.26(3H,m), 7.57(1H, d, J=8Hz), 8.51(1H, s) MS m/z: 313(M + ) 4,5-Dihydro-6-[1-[2-hydroxy-2-(4-nitrophenyl) ethyl]-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one (Compound 53) Yield: 69% Appearance: light yellow powder (recrystallization from ethanol) Melting Point: 180-183.5°C (dec.) IR(KBr)cm -1 : 3488, 3220, 3083, 1659 NMR(CDCl 3 )δ: 2.47-2.79(9H, m), 2.92(1H, m), 3.23(1H, d,J=18Hz), 3.45(1H, d, J=18Hz), 4.13(1H, br), 7.57(2H, d, J=8.6Hz), 8.22(2H, d, J=8.6Hz), 8.49(1H, s) MS m/z: 344(M + ) 4,5-Dihydro-6-[1-[2-hydroxy-2-[2-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one (Compound 54) Yield: 80% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 219-221°C(dec.) IR(KBr)cm -1 : 3239, 3146, 3066, 1691 NMR(DMSO-d 6 )δ: 2.28-2.34(4H, m), 2.45(1H, m), 2.58-2.67(5H, m), 3.14-3.31(2H, m), 5.09(1H, m), 5.39(1H, d, J=4 Hz), 6.24(1H, s), 7.46(1H, m), 7.67(2H, m), 7.82(1H, m),10.71(1H, s) MS m/z: 367(M + ) 4,5-Dihydro-6-[1-(2-hydroxy-2-phenylethyl)-1,2,5,6-tetrahydropyrid-4-yl]pyridazin-3(2H)-one (Compound 55) Yield: 78% Appearance: light brown plates (recrystallization from ethanol) Melting Point: 147-155°C (dec.) IR(KBr)cm -1 : 3422, 3218, 3059, 1671 NMR(DMSO-d 6 )δ: 2.09(2H, s), 2.28-2.32(4H, m), 2.51-2.67(4H, m), 3.20(2H, d, J=3Hz), 4.74(1H, m), 5.03(1H, d, J=4Hz), 6.22(1H, brs), 7.20-7.36(5H, m), 10.70(1H, s) MS m/z: 299(M + ) Example 4: 4,5-Dihydro-3-[1-[2-hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 56) 1-[(4-Methoxyphenyl)carbonylmethyl]-4-(4,5-dihydro-1,2,4-triazin-6(1H)-one-3-yl)pyridinium bromide (300mg, 0. 0.74mmol) was dissolved in methanol (5ml), gradually added with sodium borohydride (280 mg, 7.4 mmol) under ice cooling and stirred at room temperature overnight. The solvent was removed under reduced pressure. The residue obtained was added with dichloromethane, washed with water and dried over anhydrous magnesium sulfate. The solvent was removed to obtain the titled compound (165 mg) as colorless plates. Yield: 68% Melting Point: 190-194 o C (dec.) (recrystallization from ethanol) IR(KBr)cm -1 : 3299, 3200, 1655, 1610 NMR(DMSO-d 6 )δ: 2.26(2H, br), 2.41-2.60(4H, m), 3.13(2H,br), 3.65(2H, br), 3.73(3H, s), 4.67(1H, m), 4.90(1H, d,J=4Hz), 6.20(1H, brs), 6.77(1H, s), 6.86(2H, d, J=8.5Hz),7.27(2H, d, J=8.5Hz), 10.23(1H, s) MS m/z: 330(M + ) In accordance with the procedure of Example 4, the following compounds were obtained from corresponding starting materials. 3-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one (Compound 57) Yield: 75% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 193-198°C (dec.) IR(KBr)cm -1 : 3310, 3185, 1655, 1607 NMR(DMSO-d 6 )δ: 2.25(2H, br), 2.44-2.62(4H, m), 3.13(2H,d, J=3Hz), 3.65(2H, s), 4.74(1H, m), 5.16(1H, d, J=4Hz),6.20(1H, brs), 6.77(1H, s), 7.33-7.39(4H, s), 10.24(1H, s) MS m/z: 334(M + ) 4,5-Dihydro-3-[1-[2-hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 58) Yield: 87% Appearance: colorless plates (recrystallization from methyl cellosolve) Melting Point: 200-205°C (dec.) IR(KBr)cm -1 : 3301, 3186, 1656, 1608 NMR(DMSO-d 6 )δ: 2.27(3H+2H, brs), 2.42-2.61(4H, m), 3.13(2H, d, J=2.6Hz), 3.65(2H, s), 4.69(1H, m), 4.92(1H, m), 6.20(1H, brs), 6.76(1H, s), 7.10(2H, d, J=8Hz), 7.22(2H,d, J=8Hz), 10.23 (1H, s) MS m/z: 314(M + ) 3-[1-[2-(4-Fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one (Compound 59) Yield: 62% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 203-206°C (dec.) IR(KBr)cm -1 : 3307, 3197, 3031, 1656, 1604 NMR(DMSO-d 6 )δ: 2.25(2H, brs), 2.43-2.62(4H, m), 3.13(2H,d, J=3Hz), 3.66(2H, d, J=1.5Hz), 4.74(1H, m), 5.10(1H, m), 6.20(1H, brs). 6.77(1H, s), 7.09-7.14(2H, m), 7.35-7.39(2H, m), 10.24(1H, s) MS m/z: 318(M + ) 4,5-Dihydro-3-[1-[2-hydroxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 60) Yield: 70% Appearance: light yellow powder (recrystallization from methyl cellosolve) Melting Point: 193-197°C (dec.) IR(KBr)cm -1 : 3321, 3198, 1654 NMR(DMSO-d 6 )δ : 2.25(2H, brs), 2.50-2.66(4H, m), 3.14(2H,brs), 3.66(2H, s), 4.89(1H, m), 5.46(1H, d, J=4Hz), 6.20(1H, s), 6.78(1H, s), 7.64(2H, d, J=8.8Hz), 8.19(2H, d, J=8.8Hz), 10.25(1H, s) MS m/z: 345(M + ) 4,5-Dihydro-3-[1-[2-hydroxy-2-[2-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 61) Yield: 77% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 210-214°C (dec.) IR(KBr)cm -1 : 3338, 3259, 1663, 1608 NMR(DMSO-d 6 )δ: 2.28(2H, brs), 2.43(1H, m), 2.51-2.62(3H,m), 3.09-3.21 (2H, m), 3.66(2H, s), 5.08(1H, m), 5.39 (1H, d, J=4Hz), 6.21(1H, s), 6.78(1H, s), 7.46(1H, m), 7.64-7.70(2H, m), 7.81(1H, m), 10.25(1H, s) MS m/z: 368(M + ) 4,5-Dihydro-3-[1-(2-hydroxy-2-phenylethyl)-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 62) Yield: 79% Appearance: colorless plates (recrystallization from ethanol) Melting Point: 204-208°C (dec.) IR(KBr)cm -1 : 3294, 3169, 3031, 1655, 1609 NMR(DMSO-d 6 )δ: 2.26(2H, brs), 2.44-2.62(4H, m), 3.14(2H, d, J=3Hz), 3.66(2H, s), 4.73(1H, m), 5.04(1H, d, J=4Hz), 6.21(1H, s), 6.78(1H, s), 7.20-7.36(5H, m), 10.25(1H, s) MS m/z: 300(M + ) · 3-[1-[2-(4-Cyanophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one (Compound 64) Yield: 91% Appearance: yellow crystals (recrystallization from ethanol) Melting Point: 206-209°C (dec.) IR(KBr)cm -1 : 3336, 3253, 2226, 1663, 1607 NMR(DMSO-d 6 )δ: 2.23(2H, brs), 2.44-2.74(4H, m), 3.12(2H,brs), 3.64(2H, s), 4.82(1H, m), 3.53(1H, d, J=4.3Hz), 6.18(1H, brs), 6.76(1H, s), 7.54 (2H, d, J=8.6Hz), 7.77(2H, d, J=8.6Hz), 10.23(1H, s) MS m/z: 325(M + ) 3-[1-[2-(4-Aminophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one (Compound 65) Yield: 67% Appearance: opaline crystals (recrystallization from ethanol) Melting Point: 213-216°C (dec.) IR(KBr)cm -1 : 3364, 3039, 1643, 1615 NMR(DMSO-d 6 )δ: 2.26(2H, brs), 2.37-2.79(4H, m), 3.12(2H,brs), 3.66(2H, s), 4.56(1H, m), 4.64(1H, d, J=3.6Hz), 4.88(2H, s), 6.20(1H, brs), 6.49(2H, d, J=8.2Hz), 6.76 (1H, s), 6.98(2H, d, J=8.2Hz), 10.23(1H, s) MS m/z: 315(M + ) 4,5-Dihydro-3-[1-[2-hydroxy-2-(2-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 66) Yield: 75% Appearance: light yellow-brown crystals (recrystallization from ethanol) Melting Point: 195-197°C (dec.) IR(KBr)cm -1 : 3333, 3258, 3102, 1663, 1611 NMR(DMSO-d 6 )δ: 2.24(2H, brs), 2.45-2.76(4H, m), 3.10(2H,brs), 3.66(2H, s), 5.28(1H, m), 5.52(1H, d, J=4.3Hz), 6.18(1H, brs), 6.76(1H, s), 7.46-7.93(4H, m), 10.23(1H, s) MS m/z: 345(M + ) 4,5-Dihydro-3-[1-[2-hydroxy-2-(3-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 67) Yield: 85% Appearance: light brown crystals (recrystallization from ethanol) Melting Point: 185-187.5°C (dec.) IR(KBr)cm -1 : 3329, 3070, 1655, 1602 NMR(DMSO-d 6 )δ: 2.26(2H, brs), 2.45-3.10(4H, m), 3.16(2H,brs), 3.66(2H,s), 4.91(1H, m), 5.48(1H, d, J=4.0Hz), 6.20(1H, brs), 6.77(1H, s), 7.58-8.23(4H, m), 10.24(1H,s) MS m/z: 345(M + ) 4,5-Dihydro-3-[1-[2-hydroxy-2-[3,4-(methylenedioxy)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 68) Yield: 92% Appearance: colorless minute scales (recrystallization from ethanol) Melting Point: 198.5-201.5°C (dec.) IR(KBr)cm -1 : 3317, 3223, 3052, 1653, 1612 NMR(DMSO-d 6 )δ: 2.26(2H, brs), 2.39-2.62(4H, m), 3.13(2H,d, J=2.6Hz), 3.66(2H, d, J=1.0Hz), 4.65(1H, m), 4.96(1H,d, J=4.0Hz), 5.96(2H, s), 6.20(1H, brs), 6.76(1H, s), 6.81(2H, s), 6.89(1H, s), 10.23(1H, s) MS m/z: 344(M + ) 4,5-Dihydro-3-[1-[2-hydroxy-2-(4-hydroxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 72) Yield: 29% Appearance: white powder (recrystallization from ethanol) Melting Point: 211-213°C (dec.) IR(KBr)cm -1 : 3309, 3230, 1663, 1617 NMR(DMSO-d 6 )δ: 2.26(2H, brs), 2.37-2.59(4H, m), 3.12(2H,d, J=2.0Hz), 3.66(2H, s), 4.62 (1H, m), 4.80(1H, d, J=3.6Hz), 6.20 (1H, brs), 6.68 (2H, d, J=8.6Hz), 6.77(1H, s), 7.12(2H, d, J=8.6Hz), 9.20(1H, s), 10.24(1H, s) MS m/z: 316 (M + ) Example 5: 2-[1-[2-(2-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-6-methyl-4H,6H-1,3,4-thiadiazin-5-one (Compound 10) 6-Methyl-2-(4-pyridyl)-4H,6H-1,3,4-thiadiazin-5-one (415 mg, 2 mmol) and 2'-chlorophenacyl bromide (654 mg, 2.8 mmol) were dissolved in absolute ethanol (6 ml) and stirred at room temperature for one day. The solvent was removed under reduced pressure to obtain 1-[(2-chlorophenyl)carbonylmethyl]-4-(6-methyl-4H,6H-1,3,4-thiadiazin-5-one-2-yl)pyridinium bromide as yellow brown gum. The salt was dissolved in methanol (7 ml), gradually added with sodium borohydride (756 mg, 20 mmol) under ice cooling and stirred at room temperature overnight. The solvent was removed under reduced pressure. The residue obtained was separated by column chromatography (dichloromethane-methanol=40:1) and purified to obtain the titled compound (621 mg) as opaline plates. Yield: 84.7% Melting Point: 184-185°C (dec.) (recrystallization from ethanol) IR(KBr)cm -1 : 3198, 3099, 1671 NMR(DMSO-d 6 )δ : 1.27(3H, d, J=7Hz), 2.41(2H, s), 2.52-2.71(4H, m), 3.26(2H, m), 3.61(1H, q, J=6.7Hz), 5.12(1H,m), 5.32(1H, d, J=4.4Hz), 6.40 (1H, s), 7.24-7.62(4H, m),11.38(1H, s) MS m/z: 365(M + ) In accordance with the procedure of Example 5, the following compounds were obtained from corresponding starting materials. 2-[1-[2-Hydroxy-2-(4-hydroxyphenyl) ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 28) Yield: 64% Appearance: light purple powder (recrystallization from ethanol) Melting Point: 206-207°C (dec.) IR(KBr)cm -1 : 3398, 3008, 1676 NMR(DMSO-d 6 )δ: 2.35-2.65(6H m), 3.22(2H, s), 3.40(2H, s), 4.63(1H, brs), 4.83(1H, s), 6.40(1H, s), 6.68(2H, d,J=8.4Hz), 7.12(2H, d, J=8.4Hz),9.25(1H, brs), 11.36(1H,s) MS m/z: 333(M + ) 2-[1-[2-Hydroxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 31) Yield: 62% Appearance: yellow powder (recrystallization from dichloromethane) Melting Point: 196-197°C (dec.) IR(KBr)cm -1 : 3443, 3180, 3080, 1659 NMR(DMSO-d 6 )δ: 2.37(2H, s), 2.51-2.70(4H, m), 3.23(2H, s), 3.40(2H, s), 4.89(1H, brs), 5.48(1H, d, J=4Hz), 6.39(1H, s), 7.64(2H, d, J=8.8Hz), 8.19(2H, d, J=8.8Hz), 11.38(1H, s) MS m/z: 362(M + ) 2-[1-[2-Hydroxy-2-[3-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 34) Yield: 57% Appearance: white powder (recrystallization from chloroform-methanol) Melting Point: 205-207°C (dec.) IR(KBr)cm -1 : 3462, 3178, 3081, 1660 NMR(DMSO-d 6 )δ: 2.38(2H, s), 2.51-2.69(4H, m), 3.25(2H, s), 3.41(2H, s), 4.80(1H, brs), 5.34(1H, d, J=4.4Hz), 6.39(1H, s), 7.53(1H, t, J=7Hz), 7.58(1H, d, J=7Hz), 7.65(1H, d, J=7Hz), 7.70(1H, s), 11.37(1H, s) MS m/z: 385(M + ) 2-[1-[2-Hydroxy-2-(4-isopropylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 36) Yield: 61% Appearance: white powder (recrystallization from chloroform-methanol) Melting Point: 196-206°C (dec.) IR(KBr)cm -1 : 3453, 3180, 3082, 1660 NMR(CDCl 3 -DMSO-d 6 )δ: 1.24(6H, d, J=1.8Hz), 2.44(1H, brs), 2.50-2.70(4H, m), 2.85-2.95(2H, m), 3.20-3.50(4H, m+s), 3.95(1H, brs), 4.77(1H, t, J=6.8Hz), 6.48(1H, brs),7.20(2H, d, J=8.3Hz), 7.30(2H, d, J=8.3Hz), 10.05(1H, s) MS m/z: 359(M + ) 5-[1-[2-Hydroxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 45) Yield: 59.4% Appearance: light brown micaceous crystals (recrystallization from ethanol) Melting Point: 186.5-187°C (dec.) IR(KBr)cm -1 : 3194, 3074, 1639 NMR(DMSO-d 6 )δ: 2.34(2H, s), 2.54-2.71(4H, m), 3.24(2H, s), 3.92(2H, s), 4.92(1H, m), 5.46(1H, d, J=4.4Hz), 6.40 (1H, s), 7.64(2H, d, J=8.4Hz), 8.14(2H, d, J=8.4Hz), 11.37(1H,s) MS m/z: 362(M + ) 5-[1-[2-(4-Cyanophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 47) Yield: 82.7% Appearance: light brown micaceous crystals (recrystallization from ethanol) Melting Point: 189.5-191.5°C (dec.) IR(KBr)cm -1 : 3212, 3083, 2225, 1637 NMR(DMSO-d 6 )δ: 2.34(2H, s), 2.52-2.70(4H, m), 3.23(2H, m), 3.92(2H, m), 4.86(1H, m), 5.38(1H, d, J=4.4Hz), 6.40 (1H, s), 7.56(2H, d, J=8.4Hz), 7.77(2H, d, J=8.4Hz), 11.37(1H,s) MS m/z: 342(M + ) 5-[1-[2-Hydroxy-2-[3-(trifluoromethyl)phenyl]ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-3H,6H-1,3,4-thiadiazin-2-one (Compound 48) Yield: 84.2% Appearance: white crystals (recrystallization from ethanol) Melting Point: 174.5-175.5°C (dec.) IR(KBr)cm -1 : 3185, 3077, 1638 NMR(DMSO-d 6 )δ : 2.35(2H, s), 2.52-2.70(4H, m), 3.24(2H, m), 3.92(2H, m), 4.87(1H, m), 5.33(1H, d, J=4Hz) , 6.41(1H, s), 7.52-7.71(4H, m), 11.36 (1H, s) MS m/z: 385(M + ) Example 6: 2-[1-[2-Methoxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetra hydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 70) 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (150 mg, 0.43 mmol) was dissolved in methanol (5 ml), added with concentrated sulfuric acid (0.8 ml, 15 mmol) and refluxed with heating for four hours. The solution was poured into ice water and neutralized with 2N aqueous sodium hydroxide. The precipitated colorless crystals are filtered out and recrystallized from 60% aqueous ethanol solution to obtain the compound (110 mg) as light yellow fine needles. Yield: 70% Melting Point: 154-155 o C (dec.) IR(KBr)cm -1 : 3162, 3073, 1669, 1609 NMR(CDCl 3 )δ: 2.50-2.90(6H, m), 3.20(3H, s), 3.31(4H brs), 3.81(3H, s), 4.36(1H, m), 6.46(1H, brs), 6.90(2H, d, J=8.5Hz), 7.25(2H, d, J=8.5Hz), 8.75(1H, brs) MS m/z: 359(M + ) In accordance with the procedure of Example 6, the following compound was obtained from corresponding starting material. 3-[1-[2-(4-Chlorophenyl)-2-methoxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one (Compound 73) Yield: 15% Appearance: yellow powder Melting Point: 168.5°C< (dec.) NMR(CD 3 OD)δ: 2.42(2H, brs), 2.54-2.81(4H, m), 3.26-3.35(4H, m), 3.84(3H, s), 4.78-4.82(1H, m), 6.20(1H, s), 7.35(4H, s) MS m/z: 348(M + ) Example 7: 2-[1-[2-Isopropoxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 71) 2-[1-[2-Hydroxy-2-(4-methoxyphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (300 mg, 0.86 mmol) was suspended in mixed solution of isopropanol (15 ml) and benzene (25 ml), added with p-toluenesulfonic acid monohydrate (4.5 g, 0.02 mol) and refluxed for 5 hours while being dehydrated by a Dean-Stark's dehydrator. After allowing to cool to room temperature, the reaction mixture was added dropwise to 1N aqueous sodium hydroxide (30 ml). The benzen layer was separated and the water layer was further extracted three times with benzen. The benzen layer was combined with the above-mentioned benzen layer and dried over anhydrous magnesium sulfate. Benzene was removed under reduced pressure and the residue was crystallized from a little amount of ether. The solid obtained was further crystallized from ether to obtain the titled compound (145 mg) as white power. Yield: 43% Melting Point: 126-127.5°C (dec.) IR(KBr)cm -1 : 3206, 3099, 1666 NMR(DMSO-d 6 )δ: 0.98(3H, d, J=5.9Hz), 1.09(3H, d, J=5.9Hz), 2.35-2.74 (7H, m), 3.13-3.30(2H, m), 3.40(2H, s), 3.74(3H, s), 4.54-4.58(1H, m), 6.38(1H, s), 6.88(2H, d, J=8.6Hz), 7.24(2H, d, J=8.6Hz), 11.36(1H, s) MS m/z: 389(M + ) Example 8: Hydrochloride of 2-[1-[2-(4-chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 13) 2-[1-[2-(4-Chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (2.5 g, 7.1 mmol) was added to 4N hydrochloric acid/dioxane solution and stirred at room temperature for 15 minutes. The resulting precipitate was collected by filtration, washed with absolute acetone and dried in vacuum to obtain the titled hydrochloride (2.7 g) as yellow powder. Yield: quantitative Melting Point: 149-152°C (dec.) IR(KBr)cm -1 : 3259, 3204, 3106, 1686 In accordance with the procedure of Example 8, the following compounds were obtained from corresponding starting materials. Hydrochloride of 2-[1-[2-hydroxy-2-(3-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 20) Yield: 56% Appearance: light yellow powder Melting Point: 193-196°C (dec.) IR(KBr)cm -1 : 3237, 1699, 1667 Hydrochloride of 2-[1-[2-hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 21) Yield: quantitative Appearance: yellow powder Melting Point: 215-220°C (dec.) IR(KBr)cm -1 : 3284, 3197, 3100, 1674 Hydrochloride of 2-[1-[2-hydroxy-2-(2,4-dimethylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 25) Yield: 91% Appearance: light pink powder Melting Point: 207-209°C (dec.) IR(KBr)cm -1 : 3226, 1676 Hydrochloride of 2-[1-[2-hydroxy-2-(3-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 30) Yield: quantitative Appearance: white powder Melting Point:157-162°C(dec.) IR(KBr)cm -1 : 3205, 3096, 1681 Hydrochloride of 2-[1-[2-(4-fluorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 35) Yield: quantitative Appearance: white powder Melting Point: 200-205°C (dec.) IR(KBr)cm -1 : 3259, 1686, 1665 Hydrochloride of 4,5-dihydro-3-[1-[2-hydroxy-2-(4-nitrophenyl) ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one (Compound 60) Yield: 90% Appearance: white fine needles (recrystallization from ethanol) Melting Point: 200-203°C (dec.) IR(KBr)cm -1 : 3274, 1654 Example 9: Oxalate of 2-[1-[2-hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (Compound 21) 2-[1-[2-Hydroxy-2-(4-methylphenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4H,6H-1,3,4-thiadiazin-5-one (100 mg, 0.3 mmol) was suspended in ethanol (4 ml) and was added with oxalic acid (39 mg, 0.3 mmol). Then, the suspension was stirred at room temperature for two hours and evaporated under reduced pressure. The residue was added with a little amount of methanol and then ether to precipitate solid. The solid was collected by filtration and dried in vacuum to obtain the titled oxalate (123 mg) as white powder. Yield: 97% Melting Point: 115-120°C (dec.) IR(KBr)cm -1 : 3226, 3008, 1665 CAPABILITY OF EXPLOITATION IN INDUSTRY The compounds of the present invention can selectively increase contraction force of cardiac muscles without increasing heart rate and therefore is effective as cardiotonic agent for cure and prevention of acute and chronic heart failure.

Claims: A heterocyclic compound represented by the formula (I) or pharmaceutically acceptable acid addition salt thereof: wherein R and R 1 represent hydrogen atom or lower alkyl group having 1 to 6 carbon atoms; R 2 and R 3 may be independently same or different and represent hydrogen atom, lower alkyl group having 1 to 6 carbon atoms, lower alkoxy group having 1 to 6 carbon atoms, trifluoromethyl group, halogen atom, nitro group, amino group, cyano group or hydroxyl group or R 2 and R 3 are joined to form methylenedioxy group or forms naphthalene; and A-E represents -CH 2 -S-, -NH-CH 2 - or -CH 2 CH 2 - wherein R 4 and R 5 represent hydrogen atom or lower alkyl group having 1 to 6 carbon atoms. The compound according to claim 1 wherein R 1 represents hydrogen atom. The compound according to claim 1 or 2 wherein A-E represents -S-CH 2 - , -CH 2 -S-, -NH-CH 2 - or -CH 2 CH 2 -. The compound according to claim 1 wherein R 1 represents hydrogen atom and A-E represents -S-CH 2 -. The compound according to claim 1 wherein R 1 represents hydrogen atom; R 2 and R 3 may be independently same or different and represent hydrogen atom, lower alkyl group having 1 to 6 carbon atoms, lower alkoxy group having 1 to 6 carbon atoms, trifluoromethyl group, halogen atom, nitro group or hydroxyl group or R 2 and R 3 are joined to form methylenedioxy group; and A-E represents -S-CH 2 -. The compound according to claim 1 wherein R 1 represents hydrogen atom and A-E represents -CH 2 -S-. The compound according to claim 1 wherein R 1 is hydrogen atom; R 2 and R 3 may be independently same or different and represent hydrogen atom, lower alkyl group having 1 to 6 carbon atoms, trifluoromethyl group, halogen atom, nitro group, cyano group or hydroxyl group; and A-E represents -CH 2 -S-. The compound according to claim 1 wherein R 1 is hydrogen atom and A-E represents -NH-CH 2 -. The compound according to claim 1 wherein R 1 is hydrogen atom; R 2 and R 3 may be independently same or different and represent hydrogen atom, halogen atom or nitro group; and A-E represents -NH-CH 2 -. The compound according to claim 1 wherein R 1 represents hydrogen atom and A-E represents -CH 2 CH 2 -. The compound according to claim 1 wherein R 1 represents hydrogen atom; R 2 and R 3 may be independently same or different and represent hydrogen atom, halogen atom or nitro group; and A-E represents -CH 2 CH 2 -. The compound according to claim 1 wherein said heterocyclic compound is 3-[1-[2-(4-chlorophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydro-1,2,4-triazin-6(1H)-one or 4,5-dihydro-3-[1-[2-hydroxy-2-(4-nitrophenyl)ethyl]-1,2,5,6-tetrahydropyrid-4-yl]-1,2,4-triazin-6(1H)-one. A pharmaceutical composition containing a compound as described in any of claims 1 to 12 as cardiotonic active component and a pharmaceutically acceptable diluent or carrier. The compound according to claim 1 wherein said heterocyclic compound is 6-[1-[2-(4-Cyanophenyl)-2-hydroxyethyl]-1,2,5,6-tetrahydropyrid-4-yl]-4,5-dihydropyridazin-3(2H)-one.

Inventors: KOBAYASHI HIDESHI, YAMAZAKI HIROAKI, YOSHIOKA KIMITOMO, KOBAYASHI, HIDESHI, YAMAZAKI, HIROAKI, YOSHIOKA, KIMITOMO, KOBAYASHI, HIDESHI 16-17, KAMI-SAGINOMIYA 3-CHOME, YAMAZAKI, HIROAKI 926-39, MIYAWADA, YOSHIOKA, KIMITOMO GREEN-TOWN KIYOTO
Applicants: ZENYAKU KOGYO KK, ZENYAKU KOGYO KABUSHIKI KAISHA
Application year: 1992
Main classification: C07D401
IPC codes: C07D401, C07D405, C07D417