Carbodiimides in the Synthesis of Enamino- and α-Aminophosphonates as Peptidomimetics of Analgesic/Antiinflammatory and Anticancer Agents

Carbodiimide that was generated from the condensation reaction of iminophosphorane with phenylisocyanate was allowed to react with different phosphorus nucleophiles. Thus, the in situ resulted heterocumulene reacted with dialkylhydrogenphosphonates in tetrahydrofuran (THF)/FeCl3/H2O system to give fused pyrrole- (approximate to 14%) and pyrimidinephosphonates (approximate to 57%). On the other hand, with tris-(dialkyl)aminophosphines, the reaction afforded the corresponding hexaalkylphosphinic diamides as a water-sensitive fine powder, quite stable for a few days in a desiccator. When a protonating agent was present in the reaction medium, the reaction was markedly accelerated leading to the formation of the phosphamides. Next, some saturated and unsaturated HornerEmmons reagents were applied in situ to the same carbodiimide to obtain more phosphorylated N-heterocycles. The analgesic and antiinflammatory activities of the newly synthesized compounds were investigated and showed significant activities. Finally, we further estimated the antitumor activity of five new phosphonates against four carcinoma cell lines.