Activated Nitriles in Heterocyclic Chemistry. A Novel Synthesis of Pyridones, Pyrazolo[1,5‐a]pyrimidines and Pyrazolo[1,5‐b]oxazines

Abstract

Several new pyridones, pyrazolo [ 1,5-a]pyrimidines and pyrazolo [ 1,5-b]oxazines were prepared from the cyanoacetohydrazide derivatives 1 , l l and the cinnamonitrile derivatives 2a-c. The considerable biological activities of both pyridones and pyrazoles have stimulated enormous interest in the synthesis and chemistry of this class of compounds'.'). As a part of a medicinal chemistry program3.') in our laboratories, the syntheses of several pyridones, pyrazolo[l,5-a]pyrimidines and pyrazoto[ 13-bloxazines were required.In conjugation of this work, we report here on the reaction of cyanoacethydrazide (1) with the cinnamonitrile derivatives 2 a c . Thus, it has been found that 1 reacts with benzylidenemalononitrile (2a) to yield an 1:l adduct. Several isomeric cyclic and acyclic structures seemed possible for the reaction product. Acyclic structures 3 and 4 were readily eliminated based on the 'H-NMR spectrum of the product which revealed only one singlet proton at 6 = 5.6 ppm. Acyclic structures 3 and 4 should have revealed multiplets for more

Complete Catalytic Deoxygenation of CO2 into Formamidine Derivatives

“…Some heterocyclic compounds containing condensed pyrazoles such as pyrano[2,3‐ c ]pyrazoles possess a wide spectrum of pharmacological action, including analgesic, anti‐inflammatory, vasodilating and antihypertensive activities [19–21]. Hence, the preparation and biological properties of new substituted pyrano[2,3‐ c ]pyrazoles are of interest [22–36]. For these reasons, we focused our attention on the development of a new method for the preparation of pyrano[2,3‐ c ]pyrazoles starting from spirocyclopropanepyrazoles and now report the results of our investigation, a ring‐opening/cyanomethylation and intramolecular cyclization of them in the presence of a base such as sodium hydride.…”

Ring transformation of spirocyclopropanepyrazoles into pyrano[2,3‐c]pyrazoles

“…Some heterocyclic compounds containing condensed pyrazoles such as pyrano[2,3‐ c ]pyrazoles possess a wide spectrum of pharmacological action, including analgesic, anti‐inflammatory, vasodilating and antihypertensive activities [19–21]. Hence, the preparation and biological properties of new substituted pyrano[2,3‐ c ]pyrazoles are of interest [22–36]. For these reasons, we focused our attention on the development of a new method for the preparation of pyrano[2,3‐ c ]pyrazoles starting from spirocyclopropanepyrazoles and now report the results of our investigation, a ring‐opening/cyanomethylation and intramolecular cyclization of them in the presence of a base such as sodium hydride.…”