Patent GB-1498705-A (GB)
Title: 4-(alkoxy-phenyl)-2-pyrrolidones their preparation and us
IPC: A61K31/4015
Filed: 1975-03-20
Abstract: 1498705 4-(Alkoxyphenyl)-2-pyrrolidones, their preparation and use SCHERING AG 20 March 1975 [20 March 1974] 11686/75 Heading C2C Racemic and optically active 4-(alkoxyphenyl)-2-pyrrolidones of the formula wherein each R 1  and R 2  may be the same or different and is a hydrocarbon group which is optionally substituted by one or more halogen atoms, hydroxyl groups, cyano groups, carboxyl groups, alkoxy groups, alkoxycarbonyl, carboxamido or optionally substituted amino groups, or may be a heterocyclic group containing oxygen or sulphur, or one of R 1  and R 2  is hydrogen and the other represents said hydrocarbon group, or R 1  and R 2  together represent a C 1-3  alkylene group, with the proviso that when R 1  is methyl, R 3  is H or 5-methoxy, R 4  is H and X is oxygen, R 2  is other than methyl, R 3  represents a hydrogen atom or a methoxy group, R 4  represents a hydrogen atom or an alkyl, aryl, acyl or carboxamido group, and X represents an oxygen or sulphur atom, may be prepared (a) by hydrolysing and decarboxylating a compound of the formula in which R 1 <SP>1</SP> and R 2 <SP>1</SP> each represents a hydrogen atom or the corresponding group R 1  or R 2 , and R represents an alkyl group; (b) by subjecting a compound of the formula or an acid addition salt thereof, to ring closure with the elimination of the corresponding alcohol ROH; or (c) by subjecting a compound of the formula or an acid addition salt thereof, to ring closure with the elimination of water; the product of reaction (a), (b) or (c) optionally being (i) hydrocarbylated to convert -OR 1 <SP>1</SP> and/or -OR 2 <SP>1</SP> into -OR 1  and/or -OR 2 , (ii) alkylated, arylated or acylated at the -NH- group at position 1, (iii) converted to the corresponding thione, or (iv) subjected to racemic separation. In reaction (a) the hydrolysis reaction is preferably carried out with aqueous alkali in a water-miscible solvent at a temperature of 60-150 C.; the decarboxylation reaction may be carried out by heating the corresponding carboxylic acid at 160-280 C. in vacuo or in a high-boiling inert solvent. The ring closure of process (b) may be effected in an organic solvent at 50-150 C., and in the presence of a base when the starting material is a salt. The ring closure of reaction (c) may be effected by splitting off water at 160-280 C., preferably in vacuo, and in the presence of a tertiary base when the starting material is a salt. R 1 <SP>1</SP> or R 2 <SP>1</SP>, when hydrogen atoms, may be converted into alkyl groups by known methods, e.g. by heating with the corresponding halide or tosylate in a polar solvent in the presence of a base. Modification of the imino group in the 1-position may be carried out, for example, by heating at 40-150 C. in a polar solvent in the presence of a salt-former with an alkyl, aryl or acyl halide, or the reaction with a haloaryl may be carried out in the absence of a solvent but preferably in the presence of copper powder. The exchange of carbonyl oxygen for sulphur may be effected, for example, with a polysulphide in a solvent or in suspension in the presence of a base at 30-120 C. The 4-(substituted phenyl)-2- pyrrolidone-3-carboxylic ester starting material of Formula (II) may be obtained by reacting an appropriately substituted benzaldehyde with a malonic acid dialkyl ester, reacting the benzalmalonic diester product with nitromethane in the presence of trimethyl guanidine, followed by reduction of the resulting 1-(substituted phenyl)-2-nitroethyl-malonic acid dialkyl ester with hydrogen under pressure using a Raney Ni catalyst. The 3-(substituted phenyl)-4-aminobutyric acid alkyl ester starting materials of Formula (III) may be obtained by heating the benzal-malonic acid diester (prepared above) in aqueous alcohol at 60 C. with HCN in the presence of KCN, and hydrogenating the product under pressure in the presence of PtO 2  If the additive reaction with the HCN is effected under boiling conditions, the corresponding butyric acid starting material of the Formula (IV) is obtained. 3 - Isobutoxy - 4 - methoxy - benzaldehyde is prepared by boiling 3-hydroxy-4-methoxybenzaldehyde with KOH and isobutyl bromide in ethanol. (3 - Acetoxy - 4 - methoxy - benzal) - malonic acid diethyl ester is prepared by reacting (3- hydroxy - 4 - methoxy - benzal) - malonic acid diethyl ester with acetic anhydride in the presence of pyridine, whilst cooling with ice. The corresponding 4-acetoxy-3-methoxy compound is obtained in a similar manner. 4 - (3,4 - Dihydroxy - phenyl) - 2 - pyrrolidone is obtained by reacting the corresponding 3,4- dimethoxy compound at - 80 C. under anhydrous conditions in methylene chloride with boron tribromide. The compounds of formula are neuropsychotropic agents and may be formulated and applied in a conventional manner.