An efficient one-pot synthesis of polyhydroquinolines at room temperature using HY-zeolite

An efficient one-pot synthesis of polyhydroquinolines by four-component coupling reactions of aldehydes, ethyl acetoacetate, dimedone and ammonium acetate in the presence of HY-zeolite at ambient temperature has been achieved. The conversions took shorter times to form the products in excellent yields. HY-zeolite can be recovered and reused.     

Efficient atom economical one-pot multicomponent synthesis of densely functionalized 4H-chromene derivatives

A sequential one-pot, atom economical three component reaction yielding medicinally promising ethyl 2-amino-3-cyano-4-(2-ethoxy-2-oxoethyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-4-carboxylate derivatives (4a-f) through a tandem Michael addition-cyclization reaction starting with structurally diverse cyclohexane-1,3-dione, diethyl acetylene dicarboxylate, and malononitrile has been carried out in different organic bases under solvent free condition for the optimization of maximum yield. All the formed 4H-chromenes were characterized by spectral and X-ray methods.     

Multicomponent reaction for the synthesis of highly functionalized piperidine scaffolds catalyzed by TMSI

Research on Chemical Intermediates - An efficient method for the synthesis of highly functionalized piperidines via one-pot domino reaction of β-ketoesters, aromatic aldehydes, and aromatic...     

DABCO-catalyzed multi-component domino reactions for the one-pot efficient synthesis of diverse and densely functionalized benzofurans in water

Research on Chemical Intermediates - An efficient, three-component strategy for the improved synthesis of a pharmaceutically interesting diverse kind of multi-functionalized benzofurans via one-pot...     

Iodine catalyzed one-pot five-component reactions for direct synthesis of densely functionalized piperidines

A simple and convenient one-pot multicomponent reaction (MCR) has been developed for the synthesis of highly functionalized piperidines catalyzed by molecular iodine. This strategy demonstrated five-component reactions of 1,3-dicarbonyl compounds, amines and aromatic aldehydes in methanol using 10 mol % of iodine at room temperature. This methodology provides an alternative approach for easy access of highly and fully substituted piperidines in moderate to good yields using three readily available starting materials. Notably, this method is mild, cheap, straight forward, applicable to broad range of substrates and environmentally friendly as compared to the existing methods. Synthetic and mechanistic studies are presented here.     

ZnO-beta zeolite mediated simple and efficient method for the one-pot synthesis of quinoxaline derivatives at room temperature

A rapid and an efficient one-pot method for the synthesis of quinoxalines catalysed by ZnO-beta zeolite at room temperature is described. This environmentally benign method provides several advantages over methods that are currently employed such as a simple work-up, mild reaction conditions, good to excellent yields, and a process to recover and reuse the catalyst for several cycles with consistent activity.      

Diversity oriented and chemoenzymatic synthesis of densely functionalized pyrrolidines through a highly diastereoselective Ugi multicomponent reaction

A highly diastereoselective Ugi reaction involving a chiral cyclic imine, two enantiomerically pure isocyanides and various carboxylic acids was employed for the synthesis of polyfunctionalized pyrrolidines. Both chiral substrates have been efficiently prepared by chemoenzymatic methodologies from readily available achiral substrates. This highly convergent approach can find an application in the fragment-based drug discovery process.     

Improved multicomponent,one-pot synthesis of functionalized tetrahydropyrans cardiovascular dysfunction regulators

A simple, efficient, and straightforward one-pot three-component synthesis of functionalized tetrahydropyrans ( 6a-l ) is carried-out in the presence of an inexpensive and environmentally benign Eaton's reagent as a catalyst to discover some ACE inhibitors and anti-inflammatory agents. Angiotensin-converting enzyme (ACE) is highly involved in the renin-angiotensin system and often directly associated with cardiovascular dysfunction via inflammation. Thus, the cardiovascular protective effect of newly synthesized tetrahydropyrans ( 6a-l ) was evaluated through ACE inhibition, human red blood cell (HRBC) membrane stabilization, and molecular docking studies. As the results complied, compounds 6e and 6f were identified as effective ACE inhibitors. Docking studies, HRBC based anti-inflammatory assay, and SAR studies revealed that compounds 6e and 6f could be good anti-inflammatory agents apart from ACE inhibitors.     

Organocatalyzed highly efficient synthesis of densely functionalized pyrrole-fused 1,4-dihydropyridine derivatives

Abstract

An organo base catalyzed diverse pyrrole-fused 1,4-dihydropyridines were synthesized. This one-pot, three-component domino reaction of enamino imides, aromatic aldehydes, and malononitrile/ethyl cyanoacetate was achieved by 10?mol% of DMAP under refluxing ethanol. In addition, novel bis-pyrrole-fused 1,4-dihydropyridine derivatives were also prepared by using terephthalaldehyde as a linker instead of simple aromatic aldehydes. This transformation proceeds via Knoevenagel condensation/Michael addition and N-cyclization reaction sequence and have some salient features including the use of a cost-effective catalyst, short reaction time and high atom economy. Moreover, the reusability of the catalyst was also performed up to five runs without any significant loss in activity.     

Microwave-assisted combinatorial synthesis of hexa-substituted 1,4-dihydropyridines scaffolds using one-pot two-step multicomponent reaction followed by a S-alkylation

A sequential one-pot two-step protocol for microwave-assisted synthesis of Hantzsch-type hexa-substituted 1,4-dihydropyridines has been developed. The three-component reactions of beta-aroylthioamides with aldehydes and acetonitrile derivatives produce the intermediates in situ followed by a S-alkylation to afford hexa-substituted 1,4-dihydropyridines. The reaction presumably proceeds via a Knoevenagel condensation-Michael addition-cyclocondensation-rearrangement-S N2 reaction sequence. Target compounds were obtained in high yields and simply purified by recrystallization. The novel method is complementary to the classical Hantzsch synthesis in that it is well-suited to the preparation of hexa-substituted 1,4-dihydropyridines.     

Graphene oxide: A carbocatalyst for the one-pot multicomponent synthesis of highly functionalized tetrahydropyridines

A simple, straightforward and efficient methodology is described for the synthesis of polysubstituted tetrahydropyridine via one-pot multicomponent reaction of β-ketoester, aldehyde and aniline in presence of catalytic amount of graphene oxide in acetonitrile. Graphene oxide is a versatile carbocatalyst and this is the first report on its application in a five component reaction. Good yield, usage of readily available starting material, operational simplicity, easy work-up and eco-friendly re-usable catalyst are the key features of this protocol.     

Alum as an efficient catalyst for the multicomponent synthesis of functionalized piperidines

An effective approach to the synthesis of functionalized piperidines via a one-pot multicomponent reaction of aniline, β-ketoester and aldehyde in the presence of alum as an efficient catalyst has been reported. The present procedure offers advantages such as simple workup, short reaction time and offers rapid access to a variety of functionalized piperidines.     

NaIO4-catalyzed one-pot synthesis of dihydropyrimidinones at room temperature under solvent-free conditions

Sodium periodate efficiently catalyzed the three-component Biginelli reaction of an aldehyde, α β-keto ester or β-keto ketone, and urea or thiourea at room temperature under solvent-free conditions and afforded the corresponding 3,4-dihydropyrimidine-2-(1H)-ones in excellent yields.     

Divergent synthesis of functionalized thioethers via multicomponent reaction of benzynes

Diverse functionalized thioethers were efficiently synthesized through the multicomponent reaction of benzynes, cyclic thioethers and different nucleophiles. Both inorganic salts (KF, KCl, KBr, and KSCN) and silylated reagents (TMSCN, TMSN₃, TMSCl) can be utilized as efficient nucleophiles for the reaction.     

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 multicomponent reaction for the one-pot synthesis of 4-aza-2,3-didehydropodophyllotoxin and derivatives

[reaction: see text] A convergent method has been found to prepare 4-aza-2,3-didehydropodophyllotoxin and derivatives in a one-pot procedure. The mechanism of the reaction between tetronic acid, anilines, and benzaldehydes is discussed.     

Novel and efficient synthesis of iminocoumarins via copper-catalyzed multicomponent reaction

A variety of substituted iminocoumarins are prepared in good to excellent yields via a copper-catalyzed multicomponenet reaction of sulfonyl azides, terminal alkynes, and salicylaldehydes or o-hydroxylacetophenones. The method is general, mild, versatile, and efficient. A plausible mechanism for the domino process is proposed.     

A convergent synthesis of enantiopure bicyclic scaffolds through multicomponent Ugi reaction

An efficient and convergent Ugi synthesis of enantiomerically pure N-acyl-2,5-disubstituted pyrrolidines was coupled with an appropriate secondary transformation to give two series of bicyclic derivatives, namely hexahydro pyrrolo-oxazocinediones and -diazepinediones.     

New and efficient one-pot synthesis of functionalized γ-spirolactones mediated by vinyltriphenylphosphonium salts

The addition of dimethyl acetylenedicarboxylate to isatin derivatives in the presence of triphenylphosphine leading to new highly functionalized γ-spirolactones is reported.