Studies on 2,3-Dioxopyrrolidines. Synthesis of Piperazine, Pyrrolo[4,5-b]indole, Pyrazino [5,6-b]indole and Arylazo Derivatives of Amino Acids

2,3-Dioxopyrrolidines 1 convert into 2,4-diketopiperazines 2 in one pot-reaction with hydrazoic acid. The pyrrolo[4,5-b]indole 6 was obtained by cyclization of p-methoxyphenylhydrazone 4 prepared via Japp-Klingemann reaction of 1a with p-methoxyphenyldiazonium chloride. Compound 5 undergoes Schmidt reaction to give the pyrazino[5,6-b]indole derivative 6. Reaction of 1b with some aryldiazonium chlorides yields arylhydrazono-_-alanines 8 and 9. Phenylhydrazonoglycine derivative 11 was synthesized via Schmidt reaction to 10 with hydrazoic acid.