间氨基苯乙酮 、 2,5-己二酮 在
water extract of Allium cepa L., bulb, Iran, Lowshan, Guilan Province, local store in Rasht 作用下,
以
neat (no solvent) 为溶剂,
以88 %的产率得到N-(3′-acetylphenyl)-2,5-dimethylpyrrole
the viability of a wide range of crystalline aromatic and aliphatic carboxylic acids as organocatalysts has been investigated for solvent-free Paal–Knorr pyrrole synthesisundermicrowave 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
摘要 在这项研究中,已经研究了微波活化下无溶剂的Paal-Knorr吡咯合成中各种结晶性芳族和脂肪族羧酸作为有机催化剂的可行性。在这些潜在的催化剂中,结晶水杨酸被证明是出色的催化剂,因为即使在低微波功率辐照下或模型反应的反应时间较短的情况下,其效率仍然很高。水杨酸出色的催化活性使Paal–Knorr环缩合的周转频率高达1472 h -1,这在无金属均相催化的情况下是独一无二的。这种有机催化剂的吸引人的特点是它有助于超快速的吡咯合成,并且没有金属污染的风险。 图形摘要 概要:引入了一种绿色快速的方法,该方法通过水杨酸作为催化剂(固态)与微波的组合来合成2,5-二甲基吡咯。
Naturally occurring organic acids for organocatalytic synthesis of pyrroles via Paal–Knorr reaction
In this study, common naturallyoccurring 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
在这项研究中,常见的天然有机酸,即草酸、丙二酸、琥珀酸、酒石酸和柠檬酸(作为安全、廉价和可生物降解的有机催化剂)已被用于 Paal-Knorr 吡咯合成。证明有机催化反应在 60 °C 下在乙醇中是有效的。然而,反应速率主要取决于官能团在底物芳环上的性质和位置。这种无金属工艺可以容忍一系列官能团,应该被视为制药行业的一项资产,因为在吡咯支架的合成过程中不会发生金属污染。
Cascade Synthesis of Pyrroles from Nitroarenes with Benign Reductants Using a Heterogeneous Cobalt Catalyst
A bifunctional 3d‐metal catalyst for the cascade synthesis of diverse pyrroles from nitroarenes is presented. The optimal catalytic system Co/NGr‐C@SiO2‐L is obtained by pyrolysis of a cobalt‐impregnated composite followed by subsequent selective leaching. In the presence of this material, (transfer) hydrogenation of easily available nitroarenes and subsequent Paal–Knorr/Clauson‐Kass condensation provides
Ascorbic acid as a multifunctional hydrogen bonding catalyst for Paal–Knorr synthesis of N-substituted mono- and bis-pyrroles: experimental and theoretical aspects
the catalytic mechanism of ascorbic acid in this reaction. The optimized calculations pointed out the presence of three possible bifunctional hydrogen bond donor sites and one hydrogen bond acceptor site in the molecular structure of ascorbic acid. Although all four possible complexes were studied, the two bidentate hydrogen bond complexes between ascorbic acid and the carbonyl group of hexane-2,5-dione