Agent de contraste pour rayons X

The invention comprises (1) compounds of general formula in which the substituents R1 which may be the same or different are acyl, R11 is hydrogen or methyl, R111 is methyl, and the salts thereof with bases, and the alkyl esters thereof, (2) compounds of general formula in which R1 is acyl and R111 is methyl, and the salts thereof with bases, (3) the following processes: (A) preparation of compounds of general formula in which the groups R1 which may be the same or different are acyl groups and R11 and R111 which may be the same or different are hydrogen or methyl, by reacting a compound of formula in which R represents an alkyl group, is reacted with an inorganic base and/or an amine, amide or an imide (in which process when R is methyl and R11 and R111 are both hydrogen use of inorganic base alone yields some N-methylated product): (B) reaction of a Compound I with a methylating agent to replace one or more acylamido hydrogens by methyl (methyl esterification by this process is also disclosed): (C) preliminary preparation of Compounds II in which R11 and/or R111 is methyl by reaction of the corresponding unsubstituted compound with a methylating agent: (D) preliminary preparation of Compounds II in which R11 and R111 are hydrogen by reacting with an acylating derivative of a carboxylic acid R1OH a compound of formula in which R11 and R111 are hydrogen: (E) preliminary preparation of Compounds III by iodination of a compound of formula which may itself be obtained by reduction of the corresponding dinitro compound (formation of which by esterification is mentioned): (F) preparation of N-methyl-3, 5-diacylamino-2, 4, 6-triiodobenzoic acids by reacting a 3-acylamino-5-amino-2, 4, 6-triiodobenzoic acid with a methylating agent to form the N-methyl compound which is then reacted with an acylating agent (any ester formed during reaction may be subsequently converted to the acid). Reference has been directed by the Comptroller to Specifications 748,319 and 791,997.ALSO:Compounds of general formula wherein the substituents R1 which may be the same or different are acyl, R11 is hydrogen or methyl and R111 is methyl, and their salts with bases, and their alkyl esters are said to be useful as X-ray contrast agents. Use in both soluble (intravenously) and insoluble form is mentioned. The Specification mentions that such 3,5 -