Compact tele-objective suitable as replacement objective with central shutters

摘要

The invention comprises esters of the general formula FORM:0717516/IV (b)/1 in which R1 and R2 are each hydrogen or an alkyl, cycloalkyl or aralkyl group or FORM:0717516/IV (b)/2 is a five-membered heterocyclic ring residue, R3 is hydrogen or an alkyl or alkoxyalkyl group and R4 is an alkyl or alkoxyalkyl group, and inorganic acid salts of these compounds. They are made by reacting a 1-amino-propane-diol of the formula FORM:0717516/IV (b)/3 with a derivative of aminobenzoic acid of the formula FORM:0717516/IV (b)/4 in which X represents a carboxylic acid, carboxylic acid ester or carboxylic acid halide group, in the presence of a metal alcoholate. Alternatively, the reaction may be carried out by using a corresponding derivative of p-nitro-benzoic acid and reducing and alkylating the reaction product. If desired any benzyl group present in the aliphatic alkylamino group of the esters obtained may be split off by catalytic hydrogenation. Many amino-propane diols which can be used as starting materials are specified in which R1 and R2 are chosen from hydrogen, methyl, ethyl, propyl, butyl, isopropyl, isobutyl benzyl and cyclohexyl groups, or N, R1 and R2 together form a pyrrolidino group. Specified alkylaminobenzoic acids which may be used as starting materials include those in which the alkyl group is a methyl, ethyl, propyl, isopropyl, butyl or isobutyl group. In examples there are prepared according to the invention (1) and (8) p-propylaminobenzoic acid g - dimethylamino - b - hydroxypropyl ester; (2) p - propylaminobenzoic acid g -pyrrolidino - b - hydroxypropyl ester; (3) p-butylaminobenzoic acid - g - pyrrolidino - b -hydroxypropyl ester; (4) p - butylaminobenzoic acid - g - diethylamino - b - hydroxypropyl ester; (5) p - isopropylaminobenzoic acid - g - diethylamino - b - hydroxypropyl ester; (6) p - diethylaminobenzoic acid g - di-methylamino - b - hydroxypropyl ester; (7) o-butylaminobenzoic acid - g - dimethylamino-b - hydroxypropyl ester; (9) p - propylaminobenzoic acid - g - amino - b - hydroxypropyl ester; (10) p - ethylaminobenzoic acid - g -pyrrolidino - b - hydroxypropyl ester; (11) p-propylaminobenzoic acid - g - methylamino-b - hydroxypropyl ester; (12) p - butylaminobenzoic acid - g - benzylmethylamino - b -hydroxypropyl ester; (13) p - butylaminobenzoic acid - g - methylamino - b - hydroxypropyl ester; (14 and (16) p - butylaminobenzoic acid - g - amino - b - hydroxypropyl ester; (15) p - (b - methoxyethylamino) - benzoic acid - g - dimethylamino - b - hydroxypropyl ester; and (17) p - butylaminobenzoic acid-g - cyclohexylamino - b - hydroxypropyl ester. Specification 241,767, [Class 2(iii)], is referred to.