Simple Synthesis of Pyrroles Under Solvent-Free Conditions

Paal–Knorr condensation of 2,5-hexadione with primary amines in the presence of a catalytic amount of praseodymium(III) trifluoromethanesulfonate under solvent-free conditions has been accomplished with an excellent yield. This method is a very easy, rapid, and high-yielding reaction for the synthesis of N-substituted pyrrole derivatives.     

Formation of Four Different Aromatic Scaffolds from Nitriles through Tandem Divergent Catalysis

A zinc bromide complex, formed by the sequential reaction of nitriles with a Reformatsky reagent and terminal alkynes, is used as an intermediate for divergent palladium‐catalyzed reactions. The reaction pathway of the intermediate is precisely controlled by the choice of the reaction solvent or the palladium catalyst to quickly form four different aromatic scaffolds—arylamines, aminoindenes, pyrroles, and quinolines—starting from readily available nitriles.     

Insertion of Nitriles into Zirconocene 1‐aza‐1,3‐diene Complexes: Chemoselective Synthesis of N–H and N‐Substituted Pyrroles

The direct insertion of nitriles into zirconocene‐1‐aza‐1,3‐diene complexes provides an efficient, chemoselective, and controllable synthesis of N‐H and N‐substituted pyrroles upon acidic aqueous work‐up. The outcome of the reaction (that is, the formation of N‐H or N‐substituted pyrroles) results from the different cyclization patterns, which depend on the relative stability and reactivity of the enamine–imine tautomers formed by hydrolysis of the diazazirconacycles.     

Recyclable,Graphite-Catalyzed,Four-Component Synthesis of Functionalized Pyrroles

A facile, convenient, and multicomponent coupling strategy for the synthesis of highly functionalized pyrroles is developed using graphite as a catalyst, but devoid of moisture-sensitive metal catalysts and corrosive acidic reagents. This method involves four-component coupling reactions of ethyl acetoacetate compound or diethyl acetylene dicarboxylate, amines, aromatic aldehydes, and nitromethane without an inert atmosphere. This approach provides easy access to highly substituted pyrroles in good yields via one-pot tandem reaction. The method is very simple, straightforward, and environmentally friendly compared to the existing methods.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

异喹啉稠环吡咯化合物的合成研究进展

概述了异喹啉稠环吡咯化合物的合成方法,主要包括Tschitschibabin反应,Munchnone衍生物的1,3－偶极环加成反应,1,5－电环化反应和硝酮化合物的1,3－偶极环加成反应,参考文献20篇。     

Manganese-Catalyzed Sustainable Synthesis of Pyrroles from Alcohols and Amino Alcohols

The development of reactions that convert alcohols into important chemical compounds saves our fossil carbon resources as alcohols can be obtained from indigestible biomass such as lignocellulose. The conservation of our rare noble metals is of similar importance, and their replacement by abundantly available transition metals, such as Mn, Fe, or Co (base or nonprecious metals), in key technologies such as catalysis is a promising option. Herein, we report on the first base-metal-catalyzed synthesis of pyrroles from alcohols and amino alcohols. The most efficient catalysts are Mn complexes stabilized by PN₅P ligands whereas related Fe and Co complexes are inactive. The reaction proceeds under mild conditions at catalyst loadings as low as 0.5 mol %, and has a broad scope and attractive functional-group tolerance. These findings may inspire others to use Mn catalysts to replace Ir or Ru complexes in challenging dehydrogenation reactions.     

Microwave-Assisted Method for Synthesis of 1,3-Disubstituted Pyrroles

1,3-Disubstituted pyrroles were prepared by a microwave-assisted reaction of pyrrolidine and aldehydes in toluene as well as in solvent-free conditions. Reactions were completed in a few minutes in the solvent-free condition but a long time (up to 30 min) was necessary to complete reactions in toluene. Yields of products depended considerably on the aldehyde used.     

One-Pot Tandem Synthesis of Tetrasubstituted Pyrazoles via 1,3-Dipolar Cycloaddition Between Aryl Hydrazones and Ethyl But-2-ynoate

1,3,4,5-Tetrasubstituted pyrazoles are rapidly and regioselectively synthesized in a one-pot, three-step sequence consisting of condensation, nitrilimine generation, and cycloaddition using mercuric acetate. Newly synthesized compounds were characterized by spectral studies. Regiochemistry of compounds 6a and 8a was determined as 1,4- and 1,5-regioisomers respectively by X-ray crystallography.     

A Simple System for Preparation of Protected Glycosidic Carbohydrate Nitriles from Corresponding Oximes

Abstract

Glycosidic nitriles of protected carbohydrates were prepared efficiently and rapidly from the corresponding oximes using thionyl chloride/benzotriazole combination as dehydrating system.     

Efficient and High-Yielding Protocol for the Synthesis of Nitriles from Aldehydes

An operationally simple and high-yielding procedure has been developed for the conversion of araldehydes into the corresponding nitriles using p-toluenesulfonic acid (p-TSA) (a mild catalyst) under microwave irradiation. The products are characterized by infrared spectral analysis and by comparison of the melting and boiling points with the reported values.     

Direct Synthesis of Aromatic Nitriles from Aldehydes Using Hydroxylamine and Oxalyl Chloride

Various aromatic and heterocyclic nitriles were prepared in good to high yields in a direct one‐pot process by heating the corresponding aldehydes with hydroxylamine and oxalyl chloride as reagents.     

Efficient Route for the Synthesis of Highly Substituted Pyrroles

A mild and efficient synthesis of highly substituted pyrroles using the reaction of triphenylphosphine, α-diketone, ammonium acetate, and dialkyl acetylenedicarboxylates is described.     

离子液体中的串联有机合成反应

近年来迅速发展起来的串联反应为解决传统的有机合成反应提供了有效的途径. 将离子液体应用于串联反应, 反应不仅具有串联反应的优点, 如反应条件温和, 目标产物的选择性好、产率高, 中间体无需分离, 操作简单等, 还具有离子液体的诸多优点: 离子液体/催化剂可循环使用, 产品容易分离、纯度高等.     

Direct Synthesis of Nitriles from Aldehydes Using Chloramine-T/KI in Aqueous Ammonia

A convenient method for direct conversion of aldehydes into nitriles has been developed using chloramine-T/KI in aqueous ammonia.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

An Efficient Synthesis of Spiroquinoxalinones via Tandem Reactions

A mild and efficient synthesis of spiroquinoxalinones via tandem condensation of chlorooxoindoline 1 with benzene‐1,2‐diamines 2 is described. And a plausible mechanism for the reaction is proposed.     

Copper-Catalyzed Synthesis of Tetrasubstituted Alkenes via Regio- and anti-Selective Addition of Silylboronates to Internal Alkynes

As a new and complementary method for the synthesis of structurally defined tetrasubstituted alkenes, a copper-catalyzed regio- and anti-selective addition of silylboronates to unsymmetric internal alkynes has been developed. A variety of unactivated alkynes can be employed with high selectivity under simple and mild conditions, and the resulting products have been further functionalized by utilizing silyl and boryl groups on the alkene.