Improved method for the synthesis of 1-alkoxyaziridine-2,2-dicarboxylic acid esters

1-Alkoxyaziridine-2~2-dicarboxylic acid esters III are of interest in connection with the high pyramidal stability of the nitrogen atom [1]. The principal method for their synthesis is the reaction of alkoxyiminomalonates with diazomethane at 20~ [2]; the intermediate formation of l-alkoxy-a2-1,2,3-triazoline-5,5-dicarboxylic acid esters, the spontaneous decomposition of which leads to a mixture of esters III and alkoxyiminosuccinates, is assumed [2]. The reaction products were separated by chromatography, and the yields of esters III generally did not exceed 75% [2]. By the reaction of isonitrosomalonates Ia, b with diazomethane at -10~ we obtained for the first time stable (at low temperatures) triazolines IIa, b, the decomposition of which in the presence of boron trifluoride etherate gives esters Ill in close-to-quantitative yields.