The cleavage of heterocyclic compounds in organic synthesis II Use of 5‐nitroisatine for synthesis of various nitrogenous heterocycles

The reactions of 5‐nitroisatine were studied with nucleophiles like heterocyclic amines and alkaline hydroxide. With the use of alkaline hydroxide it was converted into 2‐amino‐5‐nitrophenylglyoxylic acid 2 , with piperidine, morpholine and carbethoxypiperazine to its amides 4a‐4c or by oxidation to 5‐nitroanthranilic acid 7. This acid was used for synthesis of 3‐hydroxy‐6‐nitro‐2‐phenyl‐1H‐quinolin‐4‐one 10. Semicarbazone of 5‐nitroisatine 11 was converted to 5‐(2‐amino‐5‐nitrophenyl)‐2,3,4,5‐tetrahydro‐1,2,4‐triazine‐3,5‐dione 12. Cyclocondensation of this compound to afford 8‐nitro‐2,3‐dihydro‐5H‐1,2,4]triazino‐5,6‐b]indol‐3‐one 13 was unsuccessful.