214542-64-0

Upstream product

• 214542-60-6 4-(2-Phenylhydrazino)-2,5-dihydrothiophene-3-carbonitrile 
• 59-88-1 phenylhydrazine hydrochloride 
• 16563-14-7 4-oxotetrahydrothiophene-3-carbonitrile 
• 95469-88-8 2-phenyl-4,6-dihydro-2H-thieno[3,4-c]pyrazol-3-amine 
• 214542-61-7 N-(2-Phenyl-2,6-dihydro-4H-thieno[3,4-c]pyrazol-3-yl)-acetamide 

Relevant academic research and scientific papers

A mild one-pot synthesis of thieno[3,4-c]pyrazoles and their conversion into pyrazole analogs of o-quinodimethane

The reaction of alkyl or aryl hydrazine hydrochlorides with 4-cyano-3-oxotetrahydrothiophene (1) in refluxing ethanol afforded, in a regioselective manner, the corresponding 2-alkyl- or 2-aryl-3-aminothieno[3,4-c]pyrazoles 3a-1 with good yields. As representative examples, the compounds 3a, 3e, and 3k, after standard acetylation procedure, have been efficiently converted into the corresponding sulfolenes 6a, 6e, and 6k which readily undergo sulfur dioxide extrusion upon heating and in the presence of dienophiles, such as N-phenylmaleimide and ethyl fumarate, give die corresponding [4+2] cycloadducts in good yields.