GB681808A - Improvements in or relating to the manufacture of intermediates for substituted cysteines - Google Patents

Abstract

The invention comprises compounds of the general formula <FORM:0681808/IV (b)/1> where R3 and R4 are alike or different and are hydrogen or alkyl or aryl radicals but not both R3 and R4 are hydrogen, and R5 and R6 are alike or different and are hydrogen or hydro carbon groups or groups containing at least one carboxyl radical or functional derivative of a carboxyl grouping, at least one of the groups R5 and R6 being a group containing at least one carboxyl radical or a functional derivative of a carboxyl grouping. These compounds may be made by reacting compounds of the general formula <FORM:0681808/IV (b)/2> with an equivalent or an excess of a substituted amine of the general formula NHR5R6, whereby molecular re-arrangement takes place. The products may be used as starting materials in the process of Specification 681,900. The compound NHR5R6 may be an aminoacid, aminoester or peptide acid or ester. In examples: (1) 4-benzylidene-2-mercapto-5-thiazolone is reacted in aqueous alkaline solution with 1 and 1.5 equivalents of glycine, respectively to give a compound of formula I where R3 and R5=H, R4=Ph and R6=CH2COOH; (2) and (3) isopropylidene-2-thiazolone and glycine or glycylglycine (3) are reacted to give a compound in which R3 and R4=CH3, R5=H and R6=CH2COOH or (3) R6=CH2CONHCH2 COOH. Similarly are prepared compounds of formula I where (a) and (b) R3=H, R4=Ph, R5=H and R6=CH2CO2Et or CHMeCO2H; (d) R3 and R4=Me, R5=H, and R6=CH (CO2H).CH2.CH2.CO2H; (4) R3 and R4=Me, R5=H, and R6=CHMeCO2H; (5) R3 and R5 H, R4=isopropyl, R6=CH2COOH. Specification 602,755 also is referred to.