Reactions of 2‐amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene and 2‐amino‐3‐cyano‐4,7‐diphenyl‐5‐methyl‐4H‐pyrano[2,3‐c] pyrazole with phenylisocyanate, carbon disulfide, and thiourea

Abstract

Abstract2‐Amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene 1a or 2‐amino‐3‐cyano‐4,7‐di‐ phenyl‐5‐methyl‐4H‐pyrano[2,3‐c]pyrazole 2a reacted with phenylisocyanate in dry pyridine to give 2‐(3‐phenylureido)‐3‐cyanobenzo[b]thiophene 1b or 2‐disubstituted amino‐3‐cyanopyranopyrazole 2b derivative. However, when 1a and 2a were refluxed with carbon disulfide in 10% ethanolic sodium hydroxide solution, they afforded the thieno[2,3‐d]pyrimidin‐2,4‐dithione derivative 5 in the former case, 2,4‐dicyano‐1,3‐bis(dithio carboxamino)cyclobuta‐1,3‐ diene 6 and pyrazolopyranopyrido[2,3‐d]pyrimidin‐ 2,4‐dithione derivative 7 in the latter one. Treatment of 2a with thiourea in refluxing ethanol in the presence of potassium carbonate gave 2,2′‐dithiobispyrimidine derivative 9 (major) in addition to pyranopyrazole derivative 10 and 2,2′‐dithiobis ethoxypyrimidine derivative 11 in minor amounts. The structures of all products were evidenced by microanalytical and spectral data. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:6–11, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20070

Chemistry of 4,4′‐(arylmethylene)‐bis(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ol)s

“…6‐amino‐3‐methyl‐1,4‐diphenyl‐1,4‐dihydropyrano[2,3‐c]pyrazole‐5‐carbonitrile 123 reacted with carbon disulfide in ethanol / NaOH to give a mixture from bispyrazole ( 134 ), pyrimidine 137 and cyclobutadiene ( 138 ) (Scheme ).…”

Four-Component Domino Strategy for the Combinatorial Synthesis of Novel 1,4-Dihydropyrano[2,3-c]pyrazol-6-amines

“…Pyrano[2,3- c ]pyrazole derivatives are known for their wide range of biological activities such as antimicrobial, insecticidal, and anti-inflammatory . Furthermore, compounds containing pyrano[2,3- c ]pyrazole moiety have been reported to exhibit enzyme inhibition, anticancer and antifungal activity apart from being significant intermediates for the construction of complex heterocycles . In view of the biological significance, there has been extensive attention toward the development of synthetic routes for the synthesis of compounds containing pyrano[2,3- c ]pyrazole core (Figure ) …”

An efficient three-component, one-pot synthesis of 2-alkylthio-4-amino-5-cyano-6-aryl(alkyl)pyrimidines in water

“…1) [20][21][22]. To the best of our knowledge, there are mainly two methods for the synthesis of 2-alkylthio-4-amino-5-cyano-6aryl(alkyl)pyrimidines [23][24][25][26][27][28][29], as shown in Scheme 1. Both require at least 2-3 synthetic steps using organic solvents under heating, which requires a tedious work-up, there is a limitation in reactant/substrates, and the method offers unsatisfactory yields.…”