5-Chloropyrazole-4-carboxaldehydes as synthon in heterocyclic synthesis

Abstract

This review presents a systematic and comprehensive survey of the method of preparation and the chemical reactivity of 5-chloropyrazole-4-carbaldehyde. These compounds are important intermediates for the synthesis of a variety of otherwise difficult to obtain, synthetically useful, and novel heterocyclic systems.

Recent progress on the chemistry of thieno[3,2‐b]quinoline derivatives (part III)

“…Our research group, in recent years, has published many scientific types of research studies [ 55–73 ] in the field of chemistry for heterocyclic compounds that have wide biological activity. Therefore, we created this review article to present it to all researchers in this field for thieno[3,2‐ b ]quinolines derivatives, In this review, we have discussed the method of synthesized and the chemical reactions of thieno[3,2‐ b ]quinolones, starting from cinnamic acid, 2‐Bromo‐5‐methoxybenzoic acid, 2‐([1H‐pyrrol‐3‐yl]thio) acetic acid, 4‐phenylbutan‐2‐one, thiophenol, thiophene, aryldithioate, and 2‐phenylquinoline.…”

Synthesis of poly-functionalized pyrazoles under Vilsmeier-Haack reaction conditions

“…One of the approaches to 3/5-chloro (or 5-bromo)-4-formyl pyrazole derivatives is based on pyrazolones which undergo haloformylation under Vilsmeier-Haack reaction. 13,20,21 Taking into account that pyrazolones are produced by refluxing of hydrazines with 1,3-dicarbonyl compounds, 22 this method was extended only for derivatives obtained from the most available representatives of 1,3-diketones or βketoesters. 13 In addition, the pyrazolones were often obtained in low yields.…”