Nitriles in Organic Synthesis: Synthesis of new pyridazine, pyridine and pyrazolo[3,4‐b]pyridine derivatives

Abstract

The reaction of diethyl monoiminomalonate with benzoylacetonitrile affords the ethyl 3‐amino‐4‐cyanopentanoate derivative 1 a. Compound 1 a condensed with salicylaldehyde to yield the coumarin 5 and coupled with arenediazonium salts to yield the arenehydrazones 6a–c. Compounds 6a, b could be converted into the aminopyridazinium carboxylate 8a, b on treatment with aqueous sodium hydroxide. The reaction of 6a–c with hydrazine and phenyl hydrazine is reported.

Synthesis of Pyrazolo[3,4‐b]pyridin‐6‐ones

“…An unusual method of synthesis of a polysubstituted pyrazolopyridine ( 249 ) was presented in [118]. Initially, the formation of 5‐phenylpent‐3‐enoate ( 247 ) occurred in the presence of triethylamine, with the conversion of the former by a phenyldiazonium salt into phenylhydrazone ( 248 ), in a 80% yield.…”

The Utility of Phosphonium Ylides in Heterocyclic Synthesis: Synthesis of Pyridazinone and Tetrahydrocinnolinone Derivatives

“…The starting arylhydrazones 1a-c were readily obtained by coupling the appropriate methylene reagents with different arenediazonium salts as previously reported. 13,14 Compounds 1a-c reacted smoothly with each of the Wittig reagents 2a,b to give directly the corresponding pyridazinone derivatives 3a-c. The structures of 3a-c were confirmed by a thorough study of their MS and NMR data.…”