124678-40-6Relevant academic research and scientific papers
Naturally occurring organic acids for organocatalytic synthesis of pyrroles via Paal–Knorr reaction
Mohsenzadeh, Farshid,Darabi, Hossein Reza,Alivand, Mahsa,Aghapoor, Kioumars,Balavar, Yadollah
, p. 5255 - 5262 (2020)
Abstract: In this study, common naturally occurring organic acids, namely oxalic, malonic, succinic, tartaric and citric acid (as safe, inexpensive, and biodegradable organocatalysts), have been employed for Paal–Knorr pyrrole synthesis. The organocatalyzed reaction proved to be effective in ethanol at 60?°C. However, the reaction rate is mainly dominated by the nature and position of functional groups on the aromatic ring of substrate. This metal-free procedure tolerates a series of functional groups and should be considered as an asset to the pharmaceutical industry since no metal contamination could take place during the synthesis of pyrrole scaffolds. Graphic abstract: [Figure not available: see fulltext.].
Crystalline salicylic acid as an efficient catalyst for ultrafast Paal–Knorr pyrrole synthesis under microwave induction
Aghapoor, Kioumars,Mohsenzadeh, Farshid,Darabi, Hossein Reza,Sayahi, Hani
, (2021)
Abstract: In this study, the viability of a wide range of crystalline aromatic and aliphatic carboxylic acids as organocatalysts has been investigated for solvent-free Paal–Knorr pyrrole synthesis under microwave activation. Among these potential catalysts, crystalline salicylic acid proved to be a remarkable catalyst because its efficiency remained high even under low microwave power irradiation or a shorter reaction time for the model reaction. The outstanding catalytic activity of salicylic acid allowed the Paal–Knorr cyclocondensation with a turnover frequency up to 1472?h?1 which is unique in the context of a metal-free homogeneous catalysis. The attractive feature of this organocatalyst is its assistance in ultrafast pyrrole synthesis with no risk of metal contamination. Graphic abstract: [Figure not available: see fulltext.] Synopsis: A green and expeditious protocol for the synthesis of 2,5-dimethylpyrroles via combination of salicylic acid as catalyst (in its solid state) and microwaves has been introduced.
Microwave-induced calcium(II) chloride-catalyzed Paal–Knorr pyrrole synthesis: a safe, expeditious, and sustainable protocol
Aghapoor, Kioumars,Mohsenzadeh, Farshid,Darabi, Hossein Reza,Rastgar, Saeed
, p. 4063 - 4072 (2018/06/19)
Abstract: Among various alkali (Na, K) and alkaline-earth (Ca, Mg, Sr, Ba) chlorides, calcium(II) chloride was found to be a cost-effective Lewis acid catalyst for solvent-free synthesis of pyrroles from primary aromatic and aliphatic amines under open-vessel focused microwave irradiation. The salient features of this environmentally benign method are high to quantitative conversion, short reaction time, safe and clean reaction profile, possibility of scale-up to multigram quantities, and use of a low-cost, widely available, nontoxic catalyst.
Indium-mediated one-pot pyrrole synthesis from nitrobenzenes and 1,4-diketones
Lee, Hyunseung,Kim, Byeong Hyo
, p. 6698 - 6708 (2013/07/26)
One-pot reduction-triggered heterocyclizations of nitrobenzene derivatives with 1,4-diketones were investigated. In the presence of indium/AcOH in toluene at 80 C, reaction of nitrobenzenes with 2,5-hexadione produced moderate to excellent yields (40-98%)
Sterically Hindered N-Aryl Pyrroles: Chromatographic Separation of Enantiomers and Barriers to Racemization
Vorkapic-Furac, Jasna,Mintas, Mladen,Burgemeister, Thomas,Mannschreck, Albrecht
, p. 713 - 718 (2007/10/02)
The novel N-aryl-2,5-dimethylpyrrole-3-carbaldehydes (1)-(7) have been synthesized by condensation of hexane-2,5-dione with the appropriate aniline and subsequent Vilsmeier-Haack formylation of the pyrrole ring.Diastereoisomeric association complexes of t
