Synthesis of 3‐Substituted‐1‐methyl‐1H‐thieno[2,3‐c]pyrazoles

A concise review on synthesis, reactions and biological importance of thienopyrazoles

“…A simple and practical six-step synthesis of new 1-methyl-1H-thieno[2,3-c]pyrazoles from 3-amino-1Hpyrazole-4-carboxylic acid ethyl ester were reported by Patrick Toto et al 52 The alkylsulfonyl pyrazoles 54a-c were prepared from 51a, 52, and 53 respectively, through the method reported by Morimoto et al 53 Magdy W. Sabaa et al 55 and Samira T. Rabie et al 56 have synthesized thieno[2,3-c]pyrazole using the Gewald reaction. The N-phenyl pyrazolone 43 undergoes the Gewald reaction and reacts with sulfur and malononitrile in equimolar ratios under reflux for 3 h in presence of triethyl amine (TEA) and absolute ethanol as a solvent to give the aminocyano derivative of thienopyrazole 61 (Scheme 18).…”

Copper-Catalyzed [4 + 1] Annulation between α-Hydroxy Ketones and Nitriles: An Approach to Highly Substituted 3(2H)-Furanones

“…Surprisingly, when we treated 1a under the optimized reaction conditions with ethyl (ethoxymethylene)­cyanoacetate ( 2v ), which is a versatile building block in organic synthesis, none of the desired products was observed. However, a 2,2,4-trisubstituted 3­(2 H )-furanone derivative, 2,2-dimethyl-4-(pyridin-2-yl)­furan-3­(2 H )-one ( 3av ), was isolated in 85% yield.…”

Facile Access to 3,5‐Dihalogenated Pyrazoles by Sydnone Cycloaddition and their Versatile Functionalization by Pd‐Catalyzed Cross‐Coupling Processes

“…Next, the methodology was successfully extended to the synthesis of diiodopyrazoles, as illustrated with the synthesis of pyrazoles 5g and 6g (Table 1, Entry 7). Finally, it was observed that our model bromosydnone 1f was unstable under the reaction conditions, which is consistent with prior observations in the literature16 and thus prevented access to isomeric 5‐bromo‐3‐iodopyrazole 5h (Table 1, Entry 8).…”