A convenient one-pot synthesis of polysubstituted pyrroles from N-protected succinimides

The dienamine products formed by the reaction between polysubstituted succinimides and the Petasis reagent were subjected to isomerization under mild acidic conditions to give polysubstituted pyrroles in excellent yields (85–95%). The scope and limitations of this methodology are explored.     

A facile synthesis of polysubstituted pyrroles

alpha-Aminoalkylcuprates prepared from CuX.2LiCl (X = Cl, CN) and 1 equiv of an alpha-lithiocarbamate undergo conjugate addition reactions to alpha,beta-alkynyl ketones in moderate to good yields, affording E:Z mixtures of alpha,beta-enones. Treatment of the conjugate adducts with PhOH/TMSCl in CH(2)Cl(2) effected carbamate deprotection and cyclization to afford a flexible two-step synthesis of substituted pyrroles.     

A straightforward highly efficient Paal-Knorr synthesis of pyrroles

A straightforward simple synthesis of substituted pyrroles using bismuth nitrate-catalyzed modified Paal-Knorr method has been accomplished with an excellent yield. This method produces pyrroles with multicyclic aromatic amines.     

Pd-catalyzed one-pot multicomponent coupling reaction for the highly regioselective synthesis of polysubstituted benzenes

[Reaction: see text] Tetrasubstituted benzenes can be efficiently synthesized in a regioselective manner from alkynes and 2-bromoacrylates by palladium-catalyzed cascade Sonogashira coupling-benzannulation reaction.     

A "one-pot" multicomponent approach to polysubstituted 4-aminopyridines

A novel and facile domino reaction has been developed to synthesize a variety of polysubstituted 4-aminopyridines from α-azidovinylketones, aldehydes and methylamine derivatives in reasonably good yields under mild conditions. Additionally, a possible mechanism is proposed.     

One-pot multicomponent synthesis of polysubstituted indolizines

Concise and efficient four-component tandem approaches to polysubstituted indolizines have been developed under metal-free and mild aerobic conditions in refluxing acetonitrile. The mechanism of the novel reactions was proposed involving the formation of pyridinium ylides and α,β-unsaturated ketones with subsequent 1,3-dipolar cycloaddition and aromatization reaction.     

Catalytic multicomponent synthesis of highly substituted pyrroles utilizing a one-pot sila-Stetter/Paal-Knorr strategy

[reaction: see text] A multicomponent synthesis of highly substituted pyrroles catalyzed by thiazolium salts has been disclosed. The reaction employs an acyl anion conjugate addition reaction of acylsilanes (sila-Stetter) and unsaturated ketones to generate 1,4-dicarbonyl compounds in situ. The subsequent addition of various amines promotes a Paal-Knorr reaction, affording the desired pyrrole nucleus in an efficient one-pot process.     

A general approach to polysubstituted pyrroles

Exposure of a range of 3-hydroxy-2-sulfonylamino-4-alkynes to excess iodine delivers good yields of a series of iodopyrroles. Unexpectedly, the hydroxyl-dihydropyrroles, which were assumed to be the first-formed intermediates, turn out to be stable entities which have been isolated for the first time.     

An efficient one-pot synthesis of tetra-substituted pyrroles

The three-component reaction of primary amines, dialkyl acetylenedicarboxylates and β-nitrostyrene derivatives in the presence of Iron(III) chloride afforded 1,2,3,4-tetra-substituted pyrroles in high yields. These reactions could precede via domino Michael addition/cyclization process.     

An efficient protocol for the one-pot multicomponent synthesis of polysubstituted pyridines by using a biopolymer-based magnetic nanocomposite

A biopolymer cellulose-based magnetic composite nanocatalyst was prepared and characterized by using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Then, it was used efficiently in the multicomponent synthesis of polysubstituted pyridines under mild reaction conditions and using an easy work-up procedure at room temperature in ethanol. The nanocatalyst can be recovered easily and reused several times without significant loss of catalytic activity.     

A modular, one-pot, four-component synthesis of polysubstituted 1,3-oxazolidines

A modular, one-pot, two-step, four-component synthesis of polysubstituted 1,3-oxzolidines is described. The method comprises two linked domino processes: an organocatalyzed domino reaction of alkyl propiolate and an aliphatic aldehydes and a microwave-assisted amine addition cyclization domino process. An alternative modular, one-pot, three-step, four-component synthesis has also been developed by linking the organocatalyzed domino process to a sequential amine addition/Yb(OTf)(3)-catalyzed enamine cyclization reaction.     

A one-pot multicomponent synthesis of polysubstituted thiophenes via the reactions of an isocyanide, α-haloketones,and β-ketodithioesters in water

An efficient synthesis of polysubstituted thiophene derivatives is achieved via the multicomponent reaction of β-ketodithioesters, α-haloketones, and cyclohexylisocyanide in aqueous medium.     

DBU-promoted tandem Michael-addition/cyclization for the synthesis of polysubstituted pyrroles

An efficient and transition-metal-free method for the synthesis of the structurally diversified pyrroles is described. Various α,β-unsaturated ynones reacted with N-substituted ethyl glycine ethyl ester hydrochlorides in the presence of DBU to form the corresponding products in good yields. This protocol has the advantages of readily available starting materials, mild reaction conditions and a wide scope of substrates, which provides a practical route for the synthesis of polysubstituted pyrroles.     

DPTA-catalyzed one-pot regioselective synthesis of polysubstituted pyridines and 1,4-dihydropyridines

With diphenylammonium triflate (DPAT) as a catalyst, the highly substituted pyridines and dihydropyridines were prepared under solvent-free conditions from aldehydes, ketones, and amines via a one-pot multi-component reaction. The advantages of this protocol include excellent yields, environmentally benign source of nitrogen, mild reaction conditions, and simple manipulation. Different source of nitrogen like urea, thiourea, inorganic ammonium salts, and organic amines were studied. In addition, a novel way was developed for the conversion of primary aliphatic amines into alcohols.     

A one-pot synthesis of polysubstituted imidazo[1,2-a]pyridines

A series of 5,7,8-polysubstituted imidazo[1,2-a]pyridines were synthesized regioselectively from in situ generated α,β-unsaturated imines and dianions derived from methyl azolyl acetates in a one-pot procedure. The targeted molecules were conveniently isolated in analytically pure form (ca. 50-70% yields) by trituration of the concentrated reaction mixtures with cold ether.     

Polyethylene glycol (PEG-400) as an efficient and recyclable reaction medium for one-pot synthesis of polysubstituted pyrroles under catalyst-free conditions

Polyethylene glycol (PEG) was found to be an inexpensive non-toxic and effective medium for the one-pot synthesis of highly functionalized pyrroles. Utilizing this protocol various pyrrole derivatives were synthesized in excellent yields. Environmental acceptability, low cost, high yields, and recyclability of the PEG are the important features of this protocol.     

A versatile one-pot multicomponent synthesis of novel quinazolinon-2-yl-tetrasubstituted thiophenes

Here, we report a versatile multicomponent synthesis of novel quinazolinon-2-yl-tetrasubstituted thiophenes by a one-pot reaction using different alkyl-3-aminobutenoates, isothiocyanates and 2-halomethyl quinazolinones in good to excellent yields. The reaction probably proceeds by an intramolecular 5-exo-trig cyclisation.     

A three-component one-pot synthesis of penta-substituted pyrroles via ring opening of α-nitroepoxides

A novel and facile one-pot reaction has been developed to synthesize a variety of penta-substituted pyrroles from α-nitroepoxides, primary amines and dialkyl acetylenedicarboxylates under the conditions without catalyst. Furthermore, the controlled experiments has been performed and a possible mechanism has also been proposed.