Both 3‐aminothieno[2,3‐b]pyridine‐2‐carboxamide derivative 4 and bis(3‐aminothieno[2,3‐b]pyridine‐2‐carboxamide) derivative 6 are prepared, starting with pyridine‐2(1H)‐thione derivative 1 incorporating 1,3‐diarylpyrazole moiety, and were taken as starting materials for the present study. Two different synthetic routes are described for the synthesis of the target materials bis(pyridothieno[1,2,3]triazin‐4‐(3H)‐one) derivative 7 and bis(pyridothienopyrimidin‐4(3H)‐one) derivatives 10 and 13. Pyridothienopyrimidin‐4(3H)‐one derivative 14 is used as a synthetic precursor for the preparation of 4‐hydrazinylpyridothieno[3,2‐d]pyrimidine derivative 18a. Compound 18a was reacted with acetylacetone to prepare the corresponding 4‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyrimidine derivative 19. Compound 18a was reacted with several reagents such as carbon disulfide to synthesize the corresponding derivatives 24–27 incorporating fused [1,2,4]triazole ring. Moreover, 2,4‐dihydrazinylpyridothieno[3,2‐d]pyrimidine derivative 31 was prepared starting from 3‐aminothieno[2,3‐b]pyridine‐2‐carbonitrile derivative 28. Compound 31 was reacted with each of acetylacetone and formic acid to afford the corresponding 2,4‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyrimidine derivative 32 and bis([1,2,4]triazolo)[4,3‐a:4′,3′‐c]pyrimidine derivative 33, respectively. Elucidation of the structures of target molecules are achieved using elemental analyses and spectral data.
The discovery of intriguing properties shown by a large number of pyrazole derivatives has sparked a surge in interest in pyrazole chemistry over the last decade. They exist in a variety of natural products, dyes, and as scaffolds in a variety of drugs and pharmaceutical active ingredients. This review demonstrated various methods for the construction of pyrazole-fused heterocycles using pyrazole-4-carbaldehydes as effective precursors. Heterocyclic compounds mentioned in this review are arranged into categories based on the size of the heterocyclic ring as well as the position and number of the heteroatoms..
In the last decade, interest in pyrazole chemistry has grown considerably due to the discovery of fascinating properties demonstrated by a large number of pyrazole derivatives. They occur in a wide range of natural products, dyes, and as scaffolds in a number of drugs and associated pharmaceutical active substances. Substantial attention has been paid to the creation of hybrid molecules in which two heterocycles are bound in a single molecule to enhance their biological effectiveness and overcome drug resistance. In this regard, this review illustrated various methods for the construction of pyrazole-substituted heterocycles and their corresponding fused derivatives using pyrazole carboxaldehydes as effective precursors. The heterocyclic systems mentioned in this review are categorized according to the type of the heterocyclic systems.
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