ChemInform Abstract: 2‐Aminothiophenes by the Gewald Reaction

Sabnis, R. W.; Rangnekar, D. W.; Sonawane, N. D.

doi:10.1002/chin.199936290

Cited by 1 publication

(1 citation statement)

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“…Although the one-pot method is well known, it has been discovered that a two-step method that involves first preparing an α,β-unsaturated nitrile by Knoevenagel condensation of a ketone with active methylenes, followed by a base-promoted reaction with sulfur, generally produces higher yields. 17 Substituted 2-aminothiophenes have been effectively synthesized using an organic base, 18 specifically amines such as morpholine, 19 diethylamine, 20 piperidine, 21 and triethylamine. 22 Alternative basic catalysts such as ionic liquids, 23 DES, 24 cesium carbonate, 25 and calcined Mg-Al hydrotalcite 26 have also been utilized for the Gewald reaction.…”

Section: Table 1 Catalyst Selection Amentioning

confidence: 99%

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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