Tetrahydroisoquinoline derivatives, processes for producing the same and fungicides containing the same

Abstract: Tetrahydroisoquinoline derivatives useful as fungicides are disclosed. One of the tetrahydroisoquinoline derivatives of the present invention is represented by the formula [I]: (wherein R¹ represents C₁ - C₅ linear or branched alkyl, C₂ - C₅ linear or branched alkenyl, C₂ - C₅ linear or branched alkynyl; R², R³, R⁴, R⁵ and R⁶, the same or different, represent hydrogen, C₁ - C₁₀ linear or branched alkyl, C₃ - C₁₀ linear or branched alkenyl, C₂ - C₁₀ linear or branched alkynyl, C₁ - C₁₀ linear or branched alkoxy, C₂ - C₁₀ linear or branched alkenyloxy, C₂ - C₁₀ linear or branched alkynyloxy, benzyloxy, hydroxy, haloalkyl, amino, mono- or di-substituted amino substituted with C₁ - C₄ linear or branched alkyl, phenyl or halogen; R² and R³ may be bonded through a group of the formula (wherein m represents an integer of 1 or 2) or to form a ring; and R⁴ and R⁵ may be bonded through a group of the formula (wherein m represents an integer of 1 or 2) or to form a ring.

Description: BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to novel tetrahydroisoquinoline derivatives, processes of producing the same and fungicides containing the same as active ingredients. II. Description of the Related Art Fungicides are indispensable in agriculture to prevent plant diseases and to increase the yield of the agricultural products. A number of agricultural fungicides are now used. However, some of them have poor fungicidal activities and some of them have restrictions on their use because of their toxicities to environment. Further, when the same or similar fungicides are used for a long time, pathogenic plant fungi which are resistant to the fungicides are generated, so that the effects of the fungicides are reduced. Thus, a fungicide with sufficient fungicidal activity, which is free from the problems on the pollution of environment and on the emergence of drug-resistant fungi is demanded. Tetrahydroisoquinoline skeleton is contained in the benzophenanetrizine alkaloids and various physiological activities thereof including anti-cancer activity are known (e.g., J. Am. Chem. Soc. 1983, 105, 2873; J. Org. Chem. 1978, 43, 286). J. Org. Chem. 1987, Vol. 52, No. 5, pages 907 to 915 disclose compounds of formula III in which: R 7 = methyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = chlorine, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methyl, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methoxyl, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = dimethylamino, or R 7 = tert-C 4 H 9 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH 2 CH(CH 3 ) 2 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH 2 -CH 3 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH(CH 3 ) 2 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen. Tetrahedron Vol. 33, pages 331 to 336 discloses compounds of formula III in which: R 7 = methyl and R 8 = R 11 = R 12 = hydrogen and R 9 = R 10 = methoxy, or R 7 = ethyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = n-propyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = iso-propyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen. J. Org. Chem. 1977, Vol.42, No. 7 pages 1111 to 1116 disclose a compound of formula III in which: R 7 = methyl, R 9 = R 10 = R 11 = R 12 = hydrogen and R 8 = methoxy. J. Org. Chem. 1987, Vol. 52, No. 24, pages 5378 to 5382 discloses compounds of formula IV in which: R 7 = methyl and R 8 = R 11 = R 12 = hydrogen and R 9 = R 10 = methoxy, or R 7 = n-butyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methoxy, or R 7 = methyl and R 8 = R 11 = R 12 = hydrogen and R 9 and R 10 are bonded through a group of the formula - O - (-CH 2 -)- O -, or R 7 = methyl and R 9 = R 10 = R 11 = R 12 = hydrogen and R 8 = methyl. However, the present inventors found novel tetrahydroisoquinoline derivatives having fungicidal activities. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel compound effective as a fungicide with sufficient fungicidal activity and which is free from the problems on the pollution of environment and on the emergence of drug-resistant fungi. The present inventors intensively studied to discover novel tetrahydroisoquinoline derivatives and that these tetrahydroisoquinoline derivatives have high fungicidal activities and have substantially no phytotoxicity against useful plants, thereby completing the present invention. That is, the present invention provides a tetrahydroisoquinoline derivative of the formula [I] and acid addition salts thereof: (wherein R 1 represents C 1 - C 5 linear or branched alkyl, C 2 - C 5 linear or branched alkenyl, C 2 - C 5 linear or branched alkynyl; R 2 , R 3 , R 4 , R 5 and R 6 , the same or different, represent hydrogen, C 1 - C 10 linear or branched alkyl, C 3 - C 10 linear or branched alkenyl, C 2 - C 10 linear or branched alkynyl, C 1 - C 10 linear or branched alkoxy, C 2 - C 10 linear or branched alkenyloxy, C 2 - C 10 linear or branched alkynyloxy, benzyloxy, hydroxy, haloalkyl, amino, mono- or di-substituted amino substituted with C 1 - C 4 linear or branched alkyl, phenyl or halogen; R 2 and R 3 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring; and R 4 may R 5 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring. The present invention also provides a tetrahydroisoquinoline derivative of the formula [III]: (wherein R 7 represents C 1 - C 5 linear or branched alkyl, C 2 - C 5 linear or branched alkenyl or C 2 - C 5 linear or branched alkynyl; R 8 , R 9 , R 10 , R 11 and R 12 , the same or different, represent hydrogen, C 1 - C 10 linear or branched alkyl, C 3 - C 10 linear or branched alkenyl, C 2 - C 10 linear or branched alkynyl, C 1 - C 10 linear or branched alkoxy, C 2 - C 10 linear or branched alkenyloxy, C 2 - C 10 linear or branched alkynyloxy, benzyloxy, hydroxy, haloalkyl, amino, mono- or di-substituted amino substituted with C 1 - C 4 linear or branched alkyl, phenyl or halogen, alkoxycarbonyloxy of the formula (wherein R 13 represents C 1 - C 10 linear or branched alkyl), or carbamoyloxy of the formula (wherein R 14 and R 15 , the same or different, represent hydrogen or C 1 - C 10 linear or branched alkyl); R 8 and R 9 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring, and R 10 and R 11 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring, but excluding compounds of formula III in which: R 7 = methyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = chlorine, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methyl, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methoxyl, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = dimethylamino, or R 7 = tert-C 4 H 9 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH 2 CH(CH 3 ) 2 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH 2 -CH 3 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH(CH 3 ) 2 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = methyl and R 8 = R 11 = R 12 = hydrogen and R 9 = R 10 = methoxy, or R 7 = ethyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = n-propyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = iso-propyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen. R 7 = methyl, R 9 = R 10 = R 11 = R 12 = hydrogen and R 8 = methoxy. The present invention further provides a tetrahydroisoquinoline derivative of the formula [IV]: (wherein R 7 , R 8 , R 9 , R 10, R 11 and R 12 represent the same meanings as in the formula [III]), but excluding compounds of formula IV in which: R 7 = methyl and R 8 = R 11 = R 12 = hydrogen and R 9 = R 10 = methoxy, or R 7 = n-butyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methoxy, or R 7 = methyl and R 8 = R 11 = R 12 = hydrogen and R 9 and R 10 are bonded through a group of the formula - O - (-CH 2 -)- O -, or R 7 = methyl and R 9 = R 10 = R 11 = R 12 = hydrogen and R 8 = methyl. The present invention still further provides fungicides comprising as active ingredients the above-mentioned tetrahydroisoquinoline derivatives according to the present invention. By the present invention, novel tetrahydroisoquinoline derivatives useful as fungicides with sufficient fungicidal activities and which are free from the problems on the pollution of environment and on the emergence of drug-resistant fungi were provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to a first aspect of the present invention, the tetrahydroisoquinoline derivative of the above-described formula [I] is provided. In the formula [I], R 1 represents C 1 - C 5 linear or branched alkyl such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl and tert-pentyl; C 2 - C 5 linear or branched alkenyl such as vinyl, allyl, isopropenyl, 1-propenyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl, 1-methyl-2-propenyl, 2-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1,1-dimethyl-2-propenyl; or C 2 - C 5 linear or branched alkynyl such as 2-propynyl, 1-methyl-2-propynyl and 1,1-dimethyl-2-propynyl. In the formula [I], R 2 , R 3 , R 4 , R 5 and R 6 , the same or different, represent hydrogen atom; C 1 - C 10 linear or branched alkyl such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, isohexyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 3-ethylbutyl, 2-ethylbutyl, 1-ethylbutyl, 1,1,2-trimethylpropyl, 2-propylpropyl, 1-propylpropyl, 1,1-dimethylbutyl, 1-ethyl-1-methylpropyl, 1,1,2,2-tetramethylpropyl, 1,1,2-trimethylbutyl, 1,1-dimethylpentyl, 1,1,2,2-tetramethypentyl or 1-ethyl-1-methylpentyl; C 3 - C 10 linear or branched alkenyl such as isopropenyl, 1-propenyl, 2-propenyl, 1-ethylvinyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,1-dimethyl-2-propenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1,1-dimethyl-2-butenyl, 1,1-dimethyl-3-butenyl, 1,1,2-trimethyl-2-butenyl, 1,1,2-trimethyl-3-butenyl or 1,1,2,2-tetramethyl-3-butenyl; C 2 - C 10 linear or branched alkynyl such as ethynyl, 1-propynyl, 2-propynyl, 1-methyl-2-propynyl, 1,1-dimethyl-2-propynyl, 2-butynyl, 1-methyl-2-butynyl, 1,1-dimethyl-2-butynyl, 1,1-dimethyl-3-butynyl, 1,1,2-trimethyl-3-butynyl or 1,1,2,2-tetramethyl-3-butynyl; C 1 - C 10 linear or branched alkoxy such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, noepentyloxy, tert-pentyloxy hexyloxy, isohexyloxy, 3-methylpentyloxy, 2-methylpentyloxy, 1-methylpentyloxy, 3-ethylbutyloxy, 2-ethylbutyloxy, 1-ethylbutyloxy, 2-propylpropyloxy and 1-propylpropyloxy; C 2 - C 10 linear or branched alkenyloxy such as vinyloxy, allyloxy, isopropenyloxy, 1-propenyloxy, 1-methyl-1-propenyloxy, 2-methyl-1-propenyloxy, 1-methyl-2-propenyloxy, 2-butenyloxy, 1-methyl-2-butenyloxy, 2-methyl-2-butenyloxy, 3-methyl-2-butenyloxy or 1,1-dimethyl-2-propenyloxy; C 2 - C 10 linear or branched alkynyloxy such as ethynyloxy, 1-propynyloxy, 2-propynyloxy, 1-methyl-2-propynyloxy or 1,1-dimethyl-2-propynyloxy; benzyloxy; hydroxy; haloalkyl such as trifluoromethyl; amino; mono- or di-substituted amino substituted with C 1 - C 4 linear or branched alkyl, such as methylamino, ethylamino, dimethylamino, propylamino, N-ethyl-N-methylamino, isopropylamino, N-isopropyl-N-methylamino, butylamino, N-butyl-N-methylamino or isobutylamino; phenyl; or halogen atom such as fluorine, chlorine, bromine or iodine. In the formula [I], R 2 and R 3 , and/or R 4 and R 5 may be bonded through a grout of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring. Examples of such substituents on the 3-position of the isoquinoline ring include 3,4-methylenedioxyphenyl, 1-naphthyl and 2-naphthyl. Examples of the acid addition salts of the tetrahydroisoquinoline derivative of the formula [I] includes agriculturally acceptable acid addition salts such as hydrogen chloride salt, hydrogen bromide salt, sulfuric acid salt, nitric acid salt, acetic acid salt, oxalic acid salt, tartaric acid salt, benzene sulfonic acid salt and methane sulfonic acid salt. The tetrahydroisoquinoline derivative represented by the formula [I] may preferably be produced by reducing a lactam derivative of the formula [II]: (wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 represent the same meanings as in the formula [I]) with a hydrogenating agent in a solvent at -10°C to 200°C, preferably 0°C to 130°C for several minutes to several days. Preferred examples of the hydrogenating agent which may be employed in the above-described reaction include lithium aluminum hydride, diborane, sodium borohydride, lithium borohydride and sodium bis(2-methoxyethoxy)aluminum hydride. The amount of the hydrogenating agent may preferably be 0.2 to 20 equivalents with respect to one equivalent of the lactam derivative of the formula [II]. Preferred examples of the solvents which may be employed include ethers such as ethyl ether, tetrahydrofuran, dioxane and bis(2-methoxyethyl)ether; tertiary amines such as pyridine and triethylamine; aromatic hydrocarbons such as benzene, toluene and xylene; alcohols such as methanol. The lactam derivative of the formula [II] may preferably be produced according to the following reaction equation [i]: In the reaction equation [i], R 1 , R 2 , R 3 , R 4 , R 5 and R 6 represent the same meanings as mentioned above. In the reaction equation [i], the tetrahydroisoquinoline derivative of the formula [VII] may preferably be produced by reacting the imine derivative of the formula [VI] with homophthalic anhydride in a solvent at -10°C to 200°C, preferably 0°C to 100°C for 5 minutes to 200 hours, preferably 30 minutes to 60 hours. The amount of the homophthalic anhydride may preferably be 0.1 equivalent to 10 equivalents per one equivalent of the imine derivative of the formula [VI]. Although the reaction may be carried out without using a solvent, the reaction is usually carried out in the presence of a solvent. Preferred examples of the solvent include nitriles such as acetonitrile and propionitrile; ethers such as ethyl ether, tetrahydrofuran, dioxane and bis(2-methoxyethyl) ether; aromatic hydrocarbons such as benzene, toluene and xylene. The lactam derivative of the formula [II] may preferably be produced by treating the tetrahydroisoquinoline derivative of the formula [VII] in a solvent in the presence of a base at 60°C to 250°C, preferably 100°C to 200°C for 5 minutes to 200 hours, preferably 30 minutes to 60 hours. Preferred examples of the base employed in this reaction include carbonates and hydrogen carbonates of alkaline metals such as sodium carbonate, potassium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate. The amount of the base may preferably be 0.1 - 10 equivalents per one equivalent of the tetrahydroisoquinoline derivative of the formula [VII]. Preferred examples of the solvent which may be employed in this reaction include aromatic hydrocarbons such as toluene and xylene; ethers such as dioxane; and polar solvents such as N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoric triamide (HMPA). According to a second aspect of the present invention, tetrahydroisoquinoline derivatives of the above-described formulae [III] and [IV] are provided. In the formulae [III] and [IV], R 7 represents C 1 - C 5 linear or branched alkyl such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl and tert-pentyl; C 2 - C 5 linear or branched alkenyl such as vinyl, allyl, isopropenyl, 1-propenyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl, 1-methyl-2-propenyl, 2-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1,1-dimethyl-2-propenyl; or C 2 - C 5 linear or branched alkynyl such as 2-propynyl, 1-methyl-2-propynyl or 1,1-dimethyl-2-propynyl. In the formulae [III] and [IV], R 8 , R 9 , R 10 , R 11 and R 12 , the same or different, represent hydrogen atom; C 1 - C 10 linear or branched alkyl such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, isohexyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 3-ethylbutyl, 2-ethylbutyl, 1-ethylbutyl, 1,1,2-trimethylpropyl, 2-propylpropyl, 1-propylpropyl, 1,1-dimethylbutyl, 1-ethyl-methylpropyl, 1,1,2,2-tetramethylpentyl or 1-ethyl-1-methylpentyl; C 3 - C 10 linear or branched alkenyl such as isopropenyl, 1-propenyl, 2-propenyl, 1-ethylvinyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,1-dimethyl-2-propenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1,1-dimethyl-2-butenyl, 1,1,2-trimethyl-3-butenyl, 1,1,2-trimethyl-2-butenyl, 1,1-dimethyl-3-butenyl, 1,1,2-trimethyl-2-butenyl, 1,1,2-trimethyl-3-butenyl or 1,1,2,2-tetramethyl-3-butenyl; C 2 - C 10 linear or branched alkynyl such as ethynyl, 1-propynyl, 2-propynyl, 1-methyl-2-propynyl, 1,1-dimethyl-2-propynyl, 2-butynyl, 1-methyl-2-butynyl, 1,1-dimethyl-2-butynyl, 1,1-dimethyl-3-butynyl, 1,1,2-trimethyl-3-butynyl or 1,1,2,2-tetramethyl-3-butynyl; C 1 - C 10 linear or branched alkoxy such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, neopentyloxy, tert-pentyloxy, hexyloxy, isohexyloxy, 3-methylpentyloxy, 2-methylpentyloxy, 1-methylpentyloxy, 3-ethylbutyloxy, 2-ethylbutyloxy, 1-ethylbutyloxy, 2-propylpropyloxy or 1-propylpropyloxy; C 2 - C 10 linear or branched alkenyloxy such as vinyloxy, allyloxy, isopropenyloxy, 1-propenyloxy, 1-methyl-1-propenyloxy, 2-methyl-1-propenyloxy, 1-methyl-2-propenyloxy, 2-butenyloxy, 1-methyl-2-butenyloxy, 2-methyl-2-butenyloxy, 3-methyl-2-butenyloxy or 1,1-dimethyl-2-propenyloxy; C 2 - C 10 linear or branched alkynyloxy such as ethynyloxy, 1-propynyloxy, 2-propynyloxy, 1-methyl-2-propynyloxy or 1,1-dimethyl-2-propynyloxy; benzyloxy; hydroxy; haloalkyl such as trifluoromethyl; amino; mono- or di-substituted amino substituted with C 1 - C 4 linear or branched alkyl such as methylamino, ethylamino, dimethylamino. propylamino, N-ethyl-N-methylamino, isopropylamino, N-isopropyl-N-methylamino, butylamino, N-butyl-N-methylamino or isobutylamino; phenyl; halogen atom such as fluorine, chlorine, bromine or iodine; alkoxycarbonyloxy of the formula (wherein R 13 represents C 1 - C 10 linear or branched alkyl) such as methoxycarbonyloxy or ethoxycarbonyloxy; or carbamoyloxy of the formula (wherein R 14 and R 15 , the same or different, represent hydrogen or C 1 - C 10 linear or branched alkyl) such as N,N-dimethylcarbamoyloxy or N-ethyl-N-methylcarbamoyloxy. In the formulae [III] and [IV], R 8 and R 9 , and/or R 10 and R 11 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring. Examples of such substituents on the 3-position of the isoquinoline ring include 3,4-methylenedioxyphenyl, 1-naphthyl and 2-naphthyl. The tetrahydroisoquinoline derivative of the formula [III] may preferably be produced by reacting an imine derivative of the formula [V]: with homophthalic anhydride in the absence or presence of a solvent at -10°C to 200°C, preferably 0°C to 100°C for 5 minutes to 200 hours, preferably 30 minutes to 60 hours. The amount of the homophthalic anhydride employed in this reaction may preferably be 0.1 to 10 equivalents per one equivalent of the imine derivative of the formula [V]. Although this reaction may be carried out in the absence of a solvent, the reaction may usually be carried out in the presence of a solvent. Preferred examples of the solvent include nitriles such as acetonitrile and propionitrile; ethers such as ethyl ether, tetrahydrofuran, dioxane and bis(2-methoxyethyl)ether; and aromatic hydrocarbons such as benzene, toluene and xylene. Since the tetrahydroisoquinoline derivative of the formula [III] has two asymmetric carbon atoms, there are four stereoisomers, and these stereoisomers constitute two pairs of enantiomers. The pairs of enantiomers may be separated into each pair of enantiomers by the conventional column chromatography or recrystallization. In the pair of enantiomers in which the methine hydrogen on the 4-position of the isoquinoline ring emerges in the side of lower magnetic field in 1 H-NMR spectrum (in DMSO-d 6 solvent), the coupling constant between the methine hydrogen on the 4-position and the methine hydrogen on the 3-position of the isoquinoline ring is J=6Hz, so that these isomers are assumed to have cis form (J. Org. Chem. 1978, 43, 286). This pair of enantiomers is herein after referred to as " cis compound". In the pair of enantiomers in which the methine hydrogen on the 4-position of the isoquinoline ring emerges in the side of higher magnetic field in 1 H-NMR spectrum (in DMSO-d 6 solvent), the coupling constant between the methine hydrogen on the 4-position and the methine hydrogen on the 3-position of the isoquinoline ring is J=0Hz, so that these isomers are assumed to have trans form (J. Org. Chem. 1978, 43, 286). This pair of enantiomers is herein after referred to as " trans compound". Both the cis compound and trans compound, as well as mixtures thereof are effective as fungicides. The tetrahydroisoquinoline derivative of the formula [IV] may preferably be produced by treating the tetrahydroisoquinoline derivative of the formula [III] in the presence of a solvent and a base at 60°C to 250°C, preferably 100°C to 200°C for 5 minutes to 200 hours, preferably 30 minutes to 60 hours. Preferred examples of the base employed in this reaction include carbonates and hydrogen carbonates of alkaline metals such as sodium carbonate, potassium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate. The amount of the base may usually be 0.1 to 10 equivalents per one equivalent of the tetrahydroisoquinoline of the formula [III]. Preferred examples of the solvent employed in this reaction include aromatic hydrocarbons such as toluene and xylene; ethers such as dioxane; polar solvents such as N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), 1,3-dimethyl-2-imidazolidinone and hexamethyl phosphoric triamide (HMPA). The tetrahydroisoquinoline derivative of the formula [III] employed as a starting material of this reaction may be cis compound, trans compound or mixtures thereof. The tetrahydroisoquinoline derivatives of the present invention have strong fungicidal activities against wide variety of fungi causing diseases in plants. More particularly, the tetrahydroisoquinoline derivatives of the present invention have fungicidal activities against, for example, rice blast ( Pyricularia oryzae ), rice sheath blight ( Rhizoctonia solani ), rice brown spot ( Cochliobolus miyabeanus ), apple powdery mildew ( Podosphaera leucotricha ), apple scab ( Venturia inaequalis ), pear scab ( Venturia nashicola ), apple blossom blight ( Sclerotinia mali ), persimmon anthracnose ( Gloeosporium kaki ), peach brown rot ( Sclerotinia cinerea ), peach scab ( Cladosporium carpophilum ), Grape gray mold ( Botrytis cinerea ), grape anthracnose ( Elsinoe ampelina ), grape ripe rot ( Glomerella cingulata ), sugar beet cercospora leaf spot ( Cercospora beticola ), peanut brown leaf spot ( Cercospora arachidicola ), peanut leaf spot ( Cercospridium personatum ), barley powdery mildew ( Erysiphe graminis f.sp. hordei ), barley snow mold ( Fusarium nivale ), wheat powdery mildew ( Erysiphe graminis f.sp. tritici ), wheat leaf rust ( Puccinia recondita ), wheat eyespot ( Pseudocercosporella herpotrichoides ), wheat spot blotch ( Drechslera sorokiniana ), cucumber downy mildew ( Pseudoperonospora cubensis ), cucumber powdery mildew ( Sphaerotheca fuliginea ), cucumber gummy stem blight ( Mycosphaerella melonis ), cucumber gray mold ( Botrytis cinerea ), cucumber scab ( Cladosporium cucumerinum ), tomato late blight ( Phytophthora infestans ), tomato leaf mold ( Cladosporium fulvum ), tomato gray mold ( Botrytis cinerea ), strawberry powdery mildew ( Sphaerotheca humuli ), hop gray mold ( Botrytis cinerea ), tobacco powdery mildew ( Erysiphe cichoracearum ), rose black spot ( Diplocarpon rosae ), orange scab ( Elsinoe fawcetii ), orange blue mold ( Penicillium italicum ), orange common green mold ( Penicillium digitatum ) and the like. Among these, the compounds of the present invention exhibit especially strong fungicidal activities against wheat powdery mildew ( Erysiphe graminis f.sp. tritici ), wheat leaf rust ( Puccinia recondita ), wheat spot blotch ( Drechslera sorokiniana ), rice blast ( Pyricularia oryzae ) and cucumber powdery mildew ( Sphaerotheca fuliginea ). The compounds of the present invention do not substantially damage the crops such as rice, wheat and cucumber, so that they are highly safe. The fungicide according to the present invention, which contains the above-described tetrahydroisoquinoline derivative of the present invention may contain the tetrahydroisoquinoline derivative alone, but usually contains an agriculturally acceptable carrier, surfactant, dispersing agent and/or other additives and is formulated into, for example, wettable powder, emulsifiable concentrate, powder or granules. These formulations may be applied directly or after diluting to an appropriate concentration. The content of the tetrahydroisoquinoline derivative in the fungicide composition may be appropriately selected and may preferably be 0.5 - 80% by weight with respect to the overall composition. The amount of the fungicide to be applied to the plants differs depending on the tetrahydroisoquinoline derivative contained therein, the disease to be treated, the degree of the disease, environment and on the formulation form of the fungicide. In cases where the formulation form of the fungicide is one which is directly applied, such as powder or granules, the amount of the fungicide to be applied may preferably be 1 - 5000 g, more preferably 5 - 1000 g per 10 ares in terms of the amount of the active ingredient. In cases where the fungicide is finally used in the form of liquid, such as emulsifiable concentrate or wettable powder, the concentration of the active ingredient in the liquid to be applied may preferably be 0.1 - 10,000 ppm, more preferably 1 - 3000 ppm. The present invention will now be described by way of examples thereof. Example 1 Production of 3-(4-t-butylphenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline (Compound No. 5) To 20 ml of THF in which 0.83 g of lithium aluminum hydride is suspended, 20 ml of a solution containing 0.32 g of 3-(4-t-butylphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline in THF was added and the mixture was heated to reflux for 4 hours. After the reaction, 10 ml of 10% aqueous sodium hydroxide solution was gradually added to the resulting mixture cooled in iced water and the generated precipitates were removed by filtration through Celite. After concentrating the filtrate, the aqueous layer was extracted with ethyl acetate (40 ml x 2). After washing the combined organic layers with brine (50 ml x 1), the organic layers were dried over anhydrous magnesium sulfate. After evaporating the solvent under reduced presssure, the residue was purified by silica gel column chromatography [hexane/ethyl acetate (6/1)] to obtain 0.24 g of 3-(4-t-butylphenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline. m.p.: 53 - 54.5°C 1 H-NMR (CDCl 3 , δ ppm) 1.30(s,9H), 2.13(s,3H), 2.88-4.22(m,5H), 7.06(s,4H), 7.27(s,4H) IR (NaCl, cm -1 ) 2970, 2770, 1510, 1455, 1370, 840, 740 Elementary Analysis(%): as C 20 H 25 N Found: C;86.26, H;9.17, N;4.61 Calcd.: C;85.97, H;9.01, N;5.01 The tetrahydroisoquinoline derivatives represented by the formula [I] according to the present invention which were obtained in essentially the same manner as in Example 1, as well as their properties are summarized in Table 1. Example 2 Production of 3-(4-hydroxyphenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline (Compound No. 44) To 30 ml of 3-(4-methoxyphenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline (Compound No. 19) in benzene, 0.85 g of aluminium chloride was added and the resulting mixture was heated to reflux for 5 hours. After completion of the reaction, the reaction mixture was allowed to cool and water was added thereto. The generated precipitates were removed by filtration through Celite. The filtrate was made alkaline with saturated aqueous sodium hydrogen carbonate solution, and the resultant was extracted with ethyl acetate. After drying the combined organic layers over anhydrous magnesium sulfate, the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography [hexane/ethyl acetate (1/1)] to obtain 0.28 g of 3-(4-hydroxyphenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline. m.p.: decomposed at 193°C 1 H-NMR (CDCl 3 + DMSO-d6, δppm) 2.09(s,3H), 2.80-4.18(m,5H), 6.74(d,J=8Hz,2H), 6.90-7.27(m,6H), 8.83(bs,1H) IR (KBr, cm -1 ) 3440, 2960, 2800, 1615, 1590, 1520, 1470, 1280, 1260, 1240, 840, 750 Elementary Analysis(%): as C 16 H 17 NO Found: C;79.92, H;7.27, N;5.75 Calcd.: C;80.30, H;7.15, N;5.85 Example 3 Production of 3-(4-t-butylphenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline hydrogen chloride salt (Compound No. 45) In 50 ml of a solution containing 0.75 g of 3-(4-t-butylphenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline in ether, hydrogen chloride gas was bubbled for 40 minutes at room temperature under stirring. The generated crystals were coliected by filtration and washed with ether to obtain 0.7 g of 3-(4-t-butylphenyl)-2-methyl-1,2,3,4-tetrahydroisoquinoline hydrogen chloride salt m.p.: decomposed at 243°C IR (KBr, cm -1 ) 2960, 2450, 1460, 840, 750, 580 Examples of formulations of the fungicides of the present invention will now be described. It should be noted that any of the tetrahydroisoquinoline derivatives according to the present invention may be formulated in essentially the same manner as in the examples which follow. In the formulation examples, all parts are by weight. Formulation Example 1 (wettable powder) Ten parts of the Compound No. 1 according to the present invention was mixed with 87.3 parts of Zeaklite (trade name, commercially available from Kunimine Kogyo) as a carrier, 1.35 parts of Neopelex (a surfactant commercially available from Kao Atlas Corporation) and 1.35 parts of Solpol 800A (a surfactant commercially available from Toho Kagaku Kogyo) and the mixture was pulverized to obtain 10% wettable powder. Formulation Example 2 (emulsifiable concentrate) Five parts of the Compound No. 2 of the present invention was mixed with 85 parts of xylene and 10 parts of Solpol 800A as a surfactant to obtain 5% emulsifiable concentrate. Formulation Example 3 (powder) Two parts of the Compound No. 3 of the present invention was uniformly mixed with 5 parts of diatomaceous earth and 93 parts of clay and the mixture was pulverized to obtain 2% powder. Formulation Example 4 (granules) Ten parts of the Compound No. 4 of the present invention was mixed with 50 parts of bentonite, 35 parts of Kunilite (trade name, commercially available from Kunimine Kogyo) and 5 parts of Solpol 800A as a surfactant and the mixture was pulverized. Ten parts of water was added to the mixture and the resultant was uniformly stirred. The resultant was extruded through sieve holes with a diameter of 0.7 mm and dried. The resultant was cut into the length of 1 - 2 mm to obtain 10% granules. Example 4 Effectiveness for Protection Against Wheat Powdery Mildew In a plastic pot sizing 8 cm x 8 cm, seeds of wheat (variety: Norin No. 61) were sown and the plants were grown in a green house. To the seedlings of wheat in Which the primary leaf was completely expanded, a liquid formulated by diluting the wettable powder prepared as in Formulation Example 1 to a prescribed concentration shown in Table 2 below was applied. After drying the plants in the air, seedlings were inoculated with spores of wheat powdery mildew and were incubated in growth chamber at 25°C. Seven days after the inoculation, the degree of damage of the overall pot was examined and the prevention value was calculated therefrom. The degree of damage is defined as follows: Degree of Damage (%) = (n1 x 1) + (n2 x 2) + (n3 x 3) + (n4 x 4) 4N x 100 N: total number of leaves examined n0: number of leaves not diseased n1: number of leaves in which the area of diseased spots is less than 25% and more than 0% n2: number of leaves in which the area of diseased spots is 25 - 50% n3: number of leaves in which the area of diseased spots is 50 - 75% n4: number of leaves in which the area of diseased spots is more than 75% The prevention value (%) is defined as follows: Prevention Value (%) = (1 - Degree of Damage in Treated Group Degree of Damage in Non-Treated Group ) x 100 The effectiveness for preventing the disease was rated into 6 ranks as follows: Rank 5: The prevention value is 90% or more Rank 4: The prevention value is not less than 80% and less than 90% Rank 3: The prevention value is not less than 70% and less than 80% Rank 2: The prevention value is not less than 60% and less than 70% Rank 1: The prevention value is not less than 50% and less than 60% Rank 0: The prevention value is less than 50% The results are shown in Table 2. Example 5 Effectiveness for Curing Wheat Powdery Mildew In a plastic pot sizing 8 cm x 8 cm, seeds of wheat (variety: Norin No. 61) were sown and the plants were grown in a green house. To the seedlings of wheat in which the primary leaf was completely expanded, spores of wheat powdery mildew was inoculated, and the plants was grown in an incubator at 25°C. On Day 1, Day 2, Day 3 and Day 4 after the inoculation, , a liquid formulated by diluting the wettable powder prepared as in Formulation Example 1 to a concentration of the active ingredient of 250 ppm was applied and the plants were again incubated in growth chamber. Seven days after the inoculation, the degree of damage of the overall pot was examined and the prevention value was calculated therefrom in the same manner as in Example 4. The effectiveness for curing the disease was also rated into 6 ranks as in Example 4. As a result, as for the Compound No. 5, the effectiveness for curing the disease was Rank 5 for the treatments on Day 1, Day 2, Day 3 and Day 4. Example 6 Effectiveness for Protection Against Wheat Leaf Rust In a plastic pot sizing 8 cm x 8 cm, seeds of wheat (variety: Norin No. 61) were sown and the plants were grown in a green house. To the seedlings of wheat in which the primary leaf was completely expanded, a liquid formulated by diluting the wettable powder prepared as in Formulation Example 1 to a prescribed concentration shown in Table 3 below was applied. After drying the plants in the air, seedlings were inoculated with spores of wheat leaf rust and were incubated in growth chamber at 25°C. Seven days after the inoculation, the degree of damage of the overall pot was examined and the prevention value was calculated therefrom in the same manner as in Example 4. The effectiveness for preventing the disease was also rated into 6 ranks as in Example 4. The results are shown in Table 3. Example 7 Effectiveness for Protection Against Rice Blast In a plastic pot sizing 8 cm x 8 cm, seeds of rice (variety: Yamahoshi) were sown and the plants were grown in a green house. When the plants were grown to have 2.5 - 3 leaves, a liquid prepared by diluting the wettable powder prepared as in Formulation Example 1 to a concentration of the active ingredient of 500 ppm was applied. After drying in the air, seedlings were inoculated with spores of rice blast and were incubated in growth chamber at 25°C. Seven days after the inoculation, the degree of damage of the overall pot was examined and the prevention value was calculated therefrom as in Example 4. The effectiveness for preventing the disease was also rated into 6 ranks as in Example 4. As for the Compound Nos. 21 and 44, the effectiveness for preventing the disease was Rank 5 and Rank 4, respectively. Example 8 Effectiveness for Protection Against Wheat Spot Blotch In a plastic pot sizing 8 cm x 8 cm, seeds of wheat (variety: Norin No. 61) were sown and the plants were grown in a green house. To the seedlings of wheat in which the primary leaf was completely expanded, a liquid formulated by diluting the wettable powder prepared as in Formulation Example 1 to a prescribed concentration shown in Table 4 below was applied. After drying the plants in the air, seedlings were inoculated with spores of wheat spot blotch and were incubated in growth chamber at 25°C. Seven days after the inoculation, the degree of damage of the overall pot was examined and the prevention value was calculated therefrom as in Example 4. The effectiveness for preventing the disease was also rated into 6 ranks as in Example 4. The results are shown in Table 4. Example 9 Effectiveness for Protection Against Cucumber Powdery Mildew In a plastic pot sizing 8 cm x 8 cm, seeds of cucumber (variety: seiho) were sown and the plants were grown in a green house. To the seedlings of cucumber in which the primary true leaf was completely expanded, a liquid formulated by diluting the wettable powder prepared as in Formulation Example 1 to a concentration of the active ingredient of 500 ppm was applied. After drying the plants in the air, seedlings were inoculated with spores of cucumber powdery mildew and were incubated in growth chamber at 25°C. Ten days after the inoculation, the degree of damage of the overall pot was examined and the prevention value was calculated therefrom as in Example 4. The effectiveness for preventing the disease was also rated into 6 ranks as in Example 4. As a result, as for the Compound No. 7, the effectiveness for preventing the disease was Rank 5. Example 10 Production of 3-(4-t-butylphenyl)-4-hydroxycarbonyl-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline (Compound Nos. 46 and 47) To 170 ml of a solution containing 18.67 g of N-(4-t-butylbenzylidene)methylamine in acetonitrile, 18.00 g of homophthalic anhydride was added and the mixture was allowed to react at room temperature for 14 hours. After evaporating the solvent under reduced pressure, the residue was purified by silica gel column chromatography [chloroform/ethyl acetate (6/1)] to obtain 33.73 g of 3-(4-t-butylphenyl)-4-hydroxycarbonyl-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline (mixture of diastereomers). The thus obtained mixture of diastereomers was again subjected to silica gel column chromatography [chloroform/ethyl acetate (6/1)] to obtain 15.2 g of cis Compound and 8.03 g of trans compound. Compound No. 46 ( cis compound) 1 H-NMR (DMSO-d 6 , δppm) 1.28(s,9H), 2.98(s,3H), 4.82(d,J=6Hz,1H), 5.17(d,J=6Hz,1H), 6.92-7.09(m,5H), 8.02-8.17(m,1H) IR (KBr, cm -1 ) 3080, 2960, 1745, 1630, 1180 Elementary Analysis (%): as C 21 H 23 NO 3 Found: C;74.88, H;6.95, N;4.42 Calcd.: C;74.75, H;6.87, N;4,15 Compound No. 47 ( trans compound) m.p.: decomposed at 252°C 1 H-NMR (DMSO-d 6 , δppm) 1.28(s,9H), 3.06(s,3H), 4.20(s,1H), 5.35(s,1H), 7.00-7.58(m,5H), 7.92-8.07(m,1H) IR (KBr, cm -1 ) 2950, 1740, 1620, 1475, 1400, 1265, 700 Elementary Analysis (%): as C 21 H 23 NO 3 Found: C;74.69, H;6.75, N;4.43 Calcd.: C;74.75, H;6.87, N;4.15 The tetrahydroisoquinoline derivatives represented by the formula [III] according to the present invention which were obtained in essentially the same manner as in Example 10, as well as their properties are summarized in Table 5. Example 11 Production of 3-(4-t-butylphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline (Compound No. 85) To 50 ml of a solution containing 9.00 g of 3-(4-t-butylphenyl)-4-hydroxycarbonyl-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline in dimethylsulfoxide, 4.20 g of sodium carbonate was added and the mixture was allowed to react at 150°C for 1 hour. After the reaction, the solvent was evaporated under reduced pressure, and 800 ml of water was added thereto, followed by extraction with ethyl acetate (100 ml x 5). The combined organic layers were washed with water (300 ml x 6) and then with brine, and were dried over anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the residue was purified by silica gel column chromatography [hexane/ethyl acetate (2/1)] to obtain 5.92 g of 3-(4-t-butylphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline. m.p.: 116 - 117°C 1 H-NMR (CDl 3 -d 6 , δppm) 1.20(s,9H), 2.74-3.20(m,4H), 3.61(dd,J=7Hz,16Hz,1H), 4.69(dd,J=3Hz,7Hz,1H), 6.70-7.38(m,7H), 7.82-8.16(m,1H) IR (KBr, cm -1 ) 2950, 1650, 1605, 1475, 1400, 1265, 825, 740 Elementary Analysis (%): as C 20 H 23 NO Found: C;81.63, H;7.73, N;4.76 Calcd.: C;81.87, H;7.90, N;4.77 The tetrahydroisoquinoline derivatives represented by the formula [IV] according to the present invention which were obtained in essentially the same manner as in Example 11, as well as their properties are summarized in Table 6. Example 12 Production of 3-(4-hydroxyphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline (Compound No. 125) To 500 ml of a solution containing 10 g of 3-(4-methoxyphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline in benzene, 20 g of aluminum chloride was added and the mixture was heated to reflux for 7 hours. After allowing the resulting mixture to cool, water was added thereto and the generated insoluble materials were removed by filtration through Celite. The filtrate was extracted with ethyl acetate and the combined organic layers were washed with brine, followed by drying over anhydrous magnesium sulfate. After evaporating the solvent, the residue was purified by silica gel column chromatography [hexane/ethyl acetate (2/1) to obtain 5.34 g of 3-(4-hydroxyphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline. m.p.: 182 - 183.5°C 1 H-NMR (CDCl 3 + DMSO-d 6 , δppm) 2.72-4.00(m,5H), 4.66(dd,J=3Hz,7Hz,1H), 6.50-7.60(m,7H), 7.72-8.28(m,1H), 8.82(s,1H) IR (KBr, cm -1 ) 3150, 1620, 1570, 1515, 1265, 725 Elementary Analysis (%): as C 16 H 15 NO 2 Found: C;76.07, H;5.80, N;5.56 Calcd.: C;75.86, H;5.96, N;5.52 Example 13 Production of 3-(4-isopropyloxyphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline (compound No. 125) To 20 ml of a solution containing 1.50 g of 3-(4-hydroxyphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline, 0.86 g of potassium carbonate and 1.24 ml of isopropyl iodide were added and the resulting mixture was heated to reflux for 21 hours. After allowing the mixture to cool, water was added thereto and the resultant was extracted with ethyl acetate. The combined organic layers were washed with brine and dried over anhydrous magnesium sulfate. After evaporating the solvent under reduced pressure, the residue was purified by silica gel column chromatography [hexane/ethyl acetate (2/1)] to obtain 1.53 g of 3-(4-isopropylozyphenyl)-2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinoline. m.p.: 115 - 116°C 1 H-NMR (CDCl 3 , δppm) 1.23(d,J=6Hz,6H), 2,70-3.15(m,4H), 3.62(dd,J=7Hz,16Hz,1H), 4.20-4.80(m,2H), 6.52-7.45(m,7H), 7,90-8.27(m,1H) IR (KBr, cm -1 ) 2980, 2900, 1640, 1510, 1240, 950, 835, 750 Elementary Analysis (%): as C 19 H 21 NO 2 Found: C;77.26; H;7.04, N;4.41 Calcd.: C;77.26, H;7.16, N;4.74 The tetrahydroisoquinoline derivatives represented by the formula [IV] according to the present invention which were obtained in essentially the same manner as in Example 13, as well as their properties are summarized in Table 7. Example 14 Effectiveness for Protection Against Wheat Powdery Mildew The effectiveness of the tetrahydroisoquinoline derivatives represented by the formula [III] or [IV] against wheat powdery mildew ( Erysiphe graminis f.sp. tritici ) was tested in the same manner as in Example 4. The concentration of the active ingredient in the liquid applied to the plants was 500 ppm. As a result, as for the Compound Nos. 48, 88, 115 and 120, the effectiveness for preventing the disease was Rank 5, and as for the Compound Nos. 92, 97 and 100, the effectiveness was Rank 4. Example 15 Effectiveness for Protection Against Wheat Leaf Rust The effectiveness of the tetrahydroisoquinoline derivatives represented by the formula [III] or [IV] according to the present invention against wheat leaf rust ( Puccinia recondita ) was tested in the same manner as in Example 6. The concentration of the active ingredient in the liquid applied to the plants was 500 ppm. As a result, as for the Compound Nos. 100 and 104, the effectiveness was Rank 5, and as for the Compound Nos. 78, 83, 103, 115 and 129, the effectiveness was Rank 4. Example 16 Effectiveness for Protection Against Rice Blast The effectiveness of the compounds represented by the formula [III] or [IV] against rice blast ( Pyricularia oryzae ) was tested in the same manner as in Example 7 (the concentration of the active ingredient in the liquid applied to the plants was 500 ppm). As a result, as for the Compound No. 103, the effectiveness was Rank 5, and as for the Compound Nos. 55, 94 and 108, the effectiveness was Rank 4. Compound No. Concentration of Effective Ingredient (ppm) Rank of Effectiveness 2 500 4 3 500 5 19 500 4 30 500 5 45 500 4

Claims: A tetrahydroisoquinoline derivative of the formula [I] and acid addition salts thereof: (wherein R 1 represents C 1 - C 5 linear or branched alkyl, C 2 - C 5 linear or branched alkenyl, C 2 - C 5 linear or branched alkynyl; R 2 , R 3 , R 4 , R 5 and R 6 , the same or different, represent hydrogen, C 1 - C 10 linear or branched alkyl, C 3 - C 10 linear or branched alkenyl, C 2 - C 10 linear or branched alkynyl, C 1 - C 10 linear or branched alkoxy, C 2 - C 10 linear or branched alkenyloxy, C 2 - C 10 linear or branched alkynyloxy, benzyloxy, hydroxy, haloalkyl, amino, mono- or di-substituted amino substituted with C 1 - C 4 linear or branched alkyl, phenyl or halogen; R 2 and R 3 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring; and R 4 and R 5 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring. A process of producing the tetrahydroisoquinoline derivative of claim 1, comprising the step of reducing a lactam derivative of the formula [II]: (wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 represent the same meanings as in the formula [I]) with a hydrogenating agent. A fungicide comprising the tetrahydroisoquinoline derivative or acid addition salt thereof according to claim 1 as an active ingredient. A tetrahydroisoquinoline derivative of the formula [III]: (wherein R 7 represents C 1 - C 5 linear or branched alkyl, C 2 - C 5 linear or branched alkenyl or C 2 - C 5 linear or branched alkynyl; R 8 , R 9 , R 10 , R 11 and R 12 , the same or different, represent hydrogen, C 1 - C 10 linear or branched alkyl, C 3 - C 10 linear or branched alkenyl, C 2 - C 10 linear or branched alkynyl, C 1 - C 10 linear or branched alkoxy, C 2 - C 10 linear or branched alkenyloxy, C 2 - C 10 linear or branched alkynyloxy, benzyloxy, hydroxy, haloalkyl, amino, mono- or di-substituted amino substituted with C 1 - C 4 linear or branched alkyl, phenyl or halogen, alkoxycarbonyloxy of the formula (wherein R 13 represents C 1 - C 10 linear or branched alkyl), or carbamoyloxy of the formula (wherein R 14 and R 15 , the same or different, represent hydrogen or C 1 - C 10 linear or branched alkyl); R 8 and R 9 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring, and R 10 and R 11 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring, but excluding compounds of formula III in which: R 7 = methyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = chlorine, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methyl, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methoxy, or R 7 = methyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = dimethylamino, or R 7 = tert-C 4 H 9 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH 2 CH(CH 3 ) 2 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH 2 -CH 3 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = CH(CH 3 ) 2 and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = methyl and R 8 = R 11 = R 12 = hydrogen and R 9 = R 10 = methoxy, or R 7 = ethyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = n-propyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = iso-propyl and R 8 = R 9 = R 10 = R 11 = R 12 = hydrogen, or R 7 = methyl and R 9 = R 10 = R 11 = R 12 = hydrogen and R 8 = methoxy. A tetrahydroisoquinoline derivative of the formula [IV]: (wherein R 7 , R 8 , R 9 , R 10 , R 11 and R 12 represent the same meanings as in the formula [III]), but excluding compounds of formula IV in which: R 7 = methyl and R 8 = R 11 = R 12 = hydrogen and R 9 = R 10 = methoxy, or R 7 = n-butyl and R 8 = R 9 = R 11 = R 12 = hydrogen and R 10 = methoxy, or R 7 = methyl and R 8 = R 11 = R 12 = hydrogen, and R 9 and R 10 are bonded through a group of the formula - O -(-CH 2 -)- O -, or R 7 = methyl and = R 9 = R 10 = R 11 = R 12 = hydrogen and R 8 = methyl. The tetrahydroisoquinoline derivative of claim 4, wherein the substituent groups on the 3-position and 4-position of the 2-oxo-1,2,3,4-tetrahydroisoquinoline ring are in the cis form. The tetrahydroisoquinoline derivative of claim 4, wherein the substituent groups on the 3-position and 4-position of the 2-oxo-1,2,3,4-tetrahydroisoquinoline ring are in the trans form. A process of producing the tetrahydroisoquinoline derivative of claim 4, comprising the step of reacting an imine derivative of the formula [V]: (wherein R 7 , R 8 , R 9 , R 10 , R 11 and R 12 represent the same meanings as in the formula [III]) with homophthalic acid anhydride. A process of producing the tetrahydroisoquinoline derivative of claim 5, comprising the step of reacting the tetrahydroisoquinoline derivative of claim 4 in the presence of a base. A fungicide comprising the tetrahydroisoquinoline derivative of claim 4 as an active ingredient. A fungicide comprising the tetrahydroisoquinoline derivative of claim 5 as an active ingredient. The use in the preparation of a fungicide of a tetrahydroisoquinoline derivative of the formula [III]: (wherein R 7 represents C 1 - C 5 linear or branched alkyl, C 2 - C 5 linear or branched alkenyl or C 2 - C 5 linear or branched alkynyl; R 8 , R 9 , R 10 , R 11 and R 12 , the same or different, represent hydrogen, C 1 - C 10 linear or branched alkyl, C 3 - C 10 linear or branched alkenyl, C 2 - C 10 linear or branched alkynyl, C 1 - C 10 linear or branched alkoxy, C 2 - C 10 linear or branched alkenyloxy, C 2 - C 10 linear or branched alkynyloxy, benzyloxy, hydroxy, haloalkyl, amino, mono- or di-substituted amino substituted with C 1 - C 4 linear or branched alkyl, phenyl or halogen, alkoxycarbonyloxy of the formula (wherein R 13 represents C 1 - C 10 linear or branched alkyl), or carbamoyloxy of the formula (wherein R 14 and R 15 , the same or different, represent hydrogen or C 1 - C 10 linear or branched alkyl); R 8 and R 9 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring, and R 10 and R 11 may be bonded through a group of the formula -O(CH 2 O- (wherein m represents an integer of 1 or 2) or (CH=CH to form a ring. The use in the preparation of a fungicide of a tetrahydroisoquinoline derivative of the formula [IV]: (wherein R 7 , R 8 , R 9 , R 10 , R 11 and R 12 represent the same meanings as in the formula [III]).

Inventors: IDE TERUHIKO, TAKASU YASUHITO, TOKUNAGA TAKUMI, TSUZUKI KENJI, WATANABE HIROYUKI, IDE, TERUHIKO, TAKASU, YASUHITO, TOKUNAGA, TAKUMI, TSUZUKI, KENJI, WATANABE, HIROYUKI
Applicants: TOSOH CORP, TOSOH CORPORATION
Application year: 1992
Main classification: C07D217
IPC codes: C07D217, A01N47, A01N43, C07D405