Piperidinium borate catalyzed Knoevenagel condensation of carbonyl compounds with active methylenes

Gavali, Kanchan D.; Kudale, Pawan; Chaturbhuj, Ganesh U.

doi:10.1016/j.tetlet.2023.154537

Cited by 3 publications

(2 citation statements)

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“…However, it is difficult to develop the Gewald reaction further because of the drawbacks of current methods, which include excess catalyst loading, complex methods, and potentially hazardous solvents. We recently developed and applied piperidinium borate 27 to catalyze the Knoevenagel condensation; we herein explore its application for synthesizing 2-aminothiophenes via the Gewald reaction. However, 2-aminothiophenes have been synthesized by various methods involving strong bases.…”

Section: Table 1 Catalyst Selection Amentioning

confidence: 99%

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Truly Catalytic Gewald Synthesis of 2-Aminothiophenes Using Piperidinium Borate (Pip Borate), a Conjugate Acid–Base Pair

Chaturbhuj,

Gavali

2023

SynOpen

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The Gewald reaction has been well-known for more than half a century as an excellent method providing bioactive 2-aminothiophene heterocycles from the reaction of carbonyl compounds, α cyanoacetates, and elemental sulfur, in the presence of amines in stoichiometric amounts. This work describes the use of salts of boric acid as conjugate acid-base pair in a truly catalytic amount for the cyclocondensation of ketones with active methylenes like malononitrile, ethyl cyanoacetate, and benzoyl acetonitrile with sulfur to give 2-aminothiophenes via Gewald reaction. The present protocol is also applied for synthesizing Tinoridine an anti-peroxidative NSAID with an excellent yield. Additionally, the catalyst has great recyclability and reusability.

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Section: Table 1 Catalyst Selection Amentioning

confidence: 99%

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confidence: 99%