GB833358A - Kainic acid and its isomers and their derivatives and a method for preparing them - Google Patents

Abstract

The invention comprises kainic acid, its isomers, their esters and N-acyl derivatives of the general formula (planar structure indicated) <FORM:0833358/IV (b)/1> wherein R1 represents hydrogen or a carbalkoxy radical having up to 5 carbon atoms, R2 and R3 each are hydrogen or alkyl radicals having up to 5 carbon atoms, R4 is hydrogen or aliphatic acyl or carbalkoxy radical having up to 5 carbon atoms, other than compounds having the planar formula <FORM:0833358/IV (b)/2> wherein R is isopropyl, isopropenyl, isopropylidene, or acetyl, R1 is hydrogen except when R is a divalent group, in which case R represents an additional bond, R2 and R3 are hydrogen or methyl, and R4 is hydrogen or acetyl, or their lactones when R is unsaturated, and wherein the stereo - chemical configuration of > CH.COOR3 of the compounds is D-form relative to the imino group and the substituents at C2 and C3 are cis to one another. The compounds are prepared by eliminating the substituent R4 of a compound of the planar structure <FORM:0833358/IV (b)/3> (wherein R1 is hydrogen or carbalkoxy, R4 is a halogen atom, a hydroxy group, an alkoxy radical, a dialkylamino group or piperidino, R5 and R6 are hydrogen or alkyl radicals, R7 is hydrogen or an aliphatic acyl or carbalkoxy radical or a benzoyl group) together with the hydrogen at a -position of the substituent at the 4-position of the nucleus, by unsaturating the 4-position substituent by a known general method, e.g. dehydrohalogenation when R4 is halo, halogenation and then dehydrohalogenation when R4 is hydroxy (or alkoxy after conversion to hydroxy), or quaternization and heating in the presence of an alkali when R4 is dialkylamino. When R4 is hydroxy or alkoxy, a second halogenation in a liquid alcoholic medium, followed by dehydrohalogenation, may be necessary to convert unreacted material or an intermediate lactone to the desired product. Examples detail the conversion of 1,2-dicarbethoxy - 3 - dicarbethoxymethyl - 4 - (b - ethoxyisopropyl) pyrrolidine to 2-carbomethoxy-3-carbomethoxymethyl - 4 - isopropenyl - pyrrolidine; 1,2 - dicarbethoxy - 3 - dicarbethoxymethyl - 4 - (b - dimethylamino - isopropyl) pyrrolidine into its 4-isopropenyl analogue and 1,2 - dicarbethoxy - 3 - carbethoxymethyl - 4 - (21 - dimethylamino - 11 - methylethyl) - pyrroldine into 1,2 - dicarbethoxy - 3 - carbethoxymethyl - 4 - isopropenyl - pyrrolidine. N - Carbalkoxy - or N - acyl - 2 - carbalkoxy3 - dicarbalkoxymethyl - 4 - (b - alkoxyisopropyl or b -dialkylaminoisopropyl) pyrrolidines and their 3-carbalkoxymethyl analogues are prepared from esters of N-carbalkoxy- or N-acyl)-N-[2 - (b - alkoxyisopropyl - or b - dialkylaminoisopropyl) - 2 - carbalkoxyethyl] glycine. Specification 795,750 is referred to.