The preparation of some aminoalkylphosphonic acids and related compounds

Abstract

Six phosphonocarboxylate esters were prepared. The esters synthesized were: [line break] triethyl phosphonoacetate [line break] diisopropyl methyl phosphonoacetate [line break] triethyl 4-methyl-2-phosphonopentanoate [line break] triethyl 2-methyl-3-phosphonopropionate [line break] trimethyl 2-methyl-3-phosphonopropionate [line break] diisopropyl methyl 3-methyl-2-phosphonopentanoate [line break] Two of the esters, triethyl 4-methyl-2-phosphonopentanoate and diisopropyl methyl 3-methyl-2-phosphonopentanoate, have not been previously reported. Four aminoalkylphosphonic acids were prepared by means of the modified Curtius reaction form the foregoing phosphonocarboxylate esters. The amino phosphonic acids prepared were: [line break] aminomethylphosphonic acid [line break] 1-amino-2methylbutylphosphonic acid [line break] 1-amino-3-methylbutylphosphonic acid [line break] 2-aminopropylphosphonic acid [line break] Three of the amino phosphonic acids, 1-amino-2methylbutylphosphonic acid, 1-amino-3-methylbutylphosphonic acid and 2-aminopropylphosphonic acid have not been previously reported, and are analogs of naturally occurring carboxylic acids. The use of a "mixed" ester (where the alkoxy portions of the phosphonic ester were isopropyl groups and the alkoxy portion of the carboxylate ester was a methyl group) as the starting ester in the modified Curtius reaction permitted longer reaction times before hydrazinolysis of the phosphonate ester, an undesirable side-reaction, became apparent. ...