88613-63-2Relevant academic research and scientific papers
Zinc tetrafluoroborate-catalysed synthesis of highly substituted pyrroles by a solvent-free reaction
Ranu, Brindaban C.,Ghosh, Sudip,Das, Arijit
, p. 220 - 221 (2006)
A simple and highly efficient synthesis of penta- and tri-substituted pyrroles has been developed using the Paal-Knorr reaction catalysed by aqueous zinc tetrafluoroborate at room temperature under solvent-free conditions.
An expeditious and highly efficient synthesis of substituted pyrroles using a low melting deep eutectic mixture
Alvi, Shakeel,Ali, Rashid
, p. 9732 - 9745 (2021/12/01)
An expeditious green method for the synthesis of diverse valued substituted pyrroles through a Paal-Knorr condensation reaction, using a variety of amines and 2,5-hexanedione/2,5-dimethoxytetrahydrofuran in the presence of a low melting mixture ofN,N’-dimethylurea andL-(+)-tartaric acid (which acts as a dual catalyst/solvent system), has fruitfully been revealed. Herein, we have disclosed the applicability of this simple yet effective strategy for the generation of mono- and dipyrroles in good to excellent yields. Moreover,C3-symmetric tripyrrolo-truxene derivatives have also been assembled by means of cyclotrimerization, Paal-Knorr and Clauson-Kaas reactions as crucial steps. Interestingly, the melting mixture was recovered and reused with only a gradual decrease in the catalytic activity (over four cycles) without any significant drop in the yield of the product. This particular methodology is simple, rapid, environmental friendly, and high yielding for the generation of a variety of pyrroles. To the best of our knowledge, the present work reveals the fastest greener method reported up to this date for the construction of substituted pyrroles by utilizing the Paal-Knorr synthetic protocol, achieving impressive yields under operationally simple reaction conditions without involving any precarious/dangerous catalysts or unsafe volatile organic solvents.
The Paal-Knorr reaction revisited. A catalyst and solvent-free synthesis of underivatized and N-substituted pyrroles
Cho, Hyejin,Madden, Richard,Nisanci, Bilal,T?r?k, Bla
, p. 1088 - 1099 (2015/03/04)
A new, modified synthesis of pyrroles is described. The reaction of 2,5-hexandione with a variety of amines yielded the expected pyrrole analogues in excellent yields. The reactions were carried out under the ultimate green conditions excluding both catalyst and solvent applying simple stirring at room temperature. The variety of amines include aqueous ammonium hydroxide for the synthesis of pyrroles with a free NH group, and benzylamines, anilines and phenylene-diamines for the synthesis of several N-derivatized pyrroles. The reaction also occurs efficiently with a variety of 1,4-diketones, although the reaction rates and yields are lower for the diketones that do not possess terminal methyl group(s). This journal is
An expeditious and solvent-free synthesis of substituted pyrroles using sulfated anatase-titania as a solid acid catalyst
Ravi, Krishnaswamy,Krishnakumar, Balu,Swaminathan, Meenakshisundaram
, p. 370 - 375 (2013/05/08)
Sulfated anatase-titania (TiO2S4 21) has been used as a solid acid catalyst for the synthesis of substituted pyrroles from diketone and aromatic/aliphatic (acyclic and cyclic) primary amines by simple physical grinding. This sulfated titania gives an excellent yield with less reaction time and is an inexpensive, easily recyclable nanocatalytic material for this reaction. Higher catalytic activity of TiO2S 4 21 is due to its increased Broonsted acidity.
Paal-Knorr pyrrole synthesis using recyclable amberlite IR 120 acidic resin: A green approach
Devi, Aarti,Shallu,Sharma,Singh, Jasvinder
experimental part, p. 1480 - 1488 (2012/05/05)
Amberlite IR 120 acidic resin, a polymer matrix, has been demonstrated as a catalyst for Paal-Knorr condensation of 2,5-hexadione with primary amines under solvent-free conditions. This is an efficient, mild, and green methodology for N-substituted pyrrole derivatives. Copyright Taylor & Francis Group, LLC.
