Patent GB-1126636-A (GB)
Title: Indole derivatives
IPC: C07D209/28
Filed: 1965-12-21
Abstract: 1,126,636. Indole derivatives. MERCK & CO. Inc. 21 Dec., 1965 [31 Dec., 1964], No. 54017/65. Heading C2C. Novel 3-indole carboxylic acid esters of the formula wherein A is a substituted or unsubstituted aromatic or heteroaromatic carboxylic acyl radical of one or two fused rings; R 1  is a hydrogen atom or a C 1-9  alkyl, C 2-9  alkenyl, alkoxyphenyl, halophenyl, cycloalkyl or aryl radical; R 2  is a hydrogen atom or a C 1-5  alkyl or C 2-5  alkenyl radical and R 6  is hydrogen or R 2  and R 6  together represent a methylene or C 2-5  alkylidene radical; R 3  is a decyl, glyceryl, dialkoxyglyceryl, mannityl, sorbityl, N-(hydroxyalkyl) piperidinyl, N-(hydroxyalkyl) pyrrolidinyl, N-(hydroxyalkyl) morpholinyl, N- alkyl(hydroxyalkyl) pyrrolidinyl, N-alkyl-(hydroxyalkyl) piperidinyl, N-alkyl-hydroxypiperidinyl, N-(hydroxyalkyl)-N-alkyl piperazinyl, tetrahydroloxy or a substituted or unsubstituted C 2-5  alkenyl, C 2-5  alkynyl, cycloalkyl or a phenyl radical or is a heterocyclic radical; R 4  is a hydrogen or fluorine atom or a C 1-5  alkyl, C 1-5  alkoxy or trifluoromethyl radical and R 5  is a hydrogen or halogen atom or a hydroxyl, C 1-5  alkyl, aryl, aminoalkyl, C 1-5  alkyl substituted amino alkyl, haloalkyl, C 1-5  alkoxy, aryloxy, aralkyloxy, alkenyloxy, alkynyloxy, cycloalkylalkoxy, cycloalkoxy, amino, C 1-5  alkylamino, di(C 1-5  alkyl) amino, C 1-5  alkanolamino, arylamino, alkylarylamino, cyano, nitro, mercapto, C 1-5  alkylthio, aralkylthio, 1-pyrrolidino, 4 - methyl - 1 - piperazino, 4 - morpholino, bis- (hydroxy C 1-5  alkyl) amino, alkanoylamino, 1- azacycloalkyl, alkylalkanoylamino, alkanoyl, bis- (benzyloxyalkyl) -amino, halobenzylthio, alkoxybenzyloxy, cycloalkyl, methoxymethyloxy, N,N-dialkylcarbamoyl, alkoxybenzylthio, sulphonamido or di(C 1-5  alkyl) sulphonamido radical, are obtained (1) by reacting phenylhydrazines with esters of levulinic acid and acylating the resulting 3-indole carboxylic esters with aromatic or heteroaromatic carboxylic acyl groups of one or two fused rings, (2) by esterifying the corresponding 3-indole carboxylic acids or (3) by esterifying acids of the formula and acylating the resulting compounds with an aromatic or heteroaromatic carboxylic acyl group of one or two fused rings. The 1-aroyl or heteroaroyl-3-indole carboxylic acid used in (2) may be obtained by acylating the corresponding 3-indole carboxylic acid (having the above formula) which may be obtained by hydrolysing the corresponding ester or amide, or by acylating this amide or ester directly and subsequently removing the ester or amide group, e.g. for a benzyl ester by hydrogenolysis or for a t-butyloxy radical, by pyrolysis. These amides or esters of the formula wherein E is an ester or amide group may be obtained (1) by converting the corresponding acid to a symmetrical or mixed anhydride and reacting this with an alcohol, (2) when R 1  represents a hydrogen atom or a methyl group and R 2  represents a hydrogen atom or a lower alkyl group by reacting an appropriately substituted phenyl hydrazine with a substituted levulinic ester or amide and cyclizing the hydrazone produced or (3) when R 2  represents an alkenyl radical, by condensing the appropriate lower alkyl 3-indole acetate with a dilower alkyl oxalate, with a strong base, removing CO from the oxalyl indolyl acetate produced by pyrolysis, alkylating the indolyl malonic ester so produced with an alkenyl halide R 2 X, hydrolysing and decarboxylating the alkenylsubstituted malonic ester and esterifying or amidating the 3-indole acetic acid produced. Amides or esters of 3-indole acrylic acids may be obtained by reacting glyoxal compounds with phosphonium alkenes. Compounds in which R 5  is a substituent joined to the indole ring via a nitrogen atom may be obtained by transforming the corresponding nitro compound, the transformation being effected before or after the acylation of the 1-position. Certain p-nitrophenyl esters of acids AOH used as acylating agents are obtained by reacting p-nitrophenol with the corresponding carboxylic acid. p-Methylthiobenzoyl chloride is obtained by reacting p-methylthiobenzoic acid with thionyl chloride, ethyl-α-ethyl levulinate is obtained by reacting the sodio derivative of ethyl acetoacetate with ethyl-α-bromobutyrate followed by hydrolysis and decarboxylation to give the α-ethyl levulinic acid which is then esterified and p-difluoromethoxybenzoic acid is prepared by reacting difluorochloromethane with benzyl p-hydroxybenzoate. Therapeutic compositions having analgesic, antipyretic, anti-inflammatory and anti-spasmodic activity and anti-gastrointestinal tract irritability contain the above 3-indole carboxylic acid esters as active ingredient. The composition may be in a form suitable for oral application. Reference has been directed by the Comptroller to Specifccation 997,638.