Multicomponent Domino Reaction from β-Ketoamides: Highly Efficient Access to Original Polyfunctionalized 2,6-Diazabicyclo[2.2.2]octane Cores

Synthesis and biological evaluation of the new ring system benzo[f]pyrimido[1,2-d][1,2,3]triazolo[1,5-a][1,4]diazepine and its cycloalkane and cycloalkene condensed analogues

Derivatives of the new ring system benzo[f]pyrimido[1,2-d][1,2,3]triazolo[1,5-a][1,4]diazepinone and its cycloalkane and cycloalkene condensed analogues have been conveniently synthesized through a three-step reaction sequence. An atom-economical, one-pot, three-step cascade process engaging five reactive centers (amide, amine, carbonyl, azide, and alkyne) has been performed for the synthesis of alicyclic derivatives of quinazolinotriazolobenzodiazepine using cyclohexane, cyclohexene, and norbornene β-amino amides. The stereochemistry and relative configurations of the synthesized compounds were determined by 1D and 2D NMR spectroscopy and X-ray crystallography. The reaction was also performed using enantiomeric starting materials leading to enantiomeric quinazolinotriazolobenzodiazepine with an ee of 95%. The synthesis of 9H-benzo[f]pyrimido[1,2-d][1,2,3]triazolo[1,5-a][1,4]diazepinone, a new heterocyclic system, was achieved in a good yield using a retro Diels-Alder (RDA) procedure. Some compounds were tested for antiproliferative activities against five human cancer cell lines of gynecological.

Three-component reaction involving isoquinoline and dimethyl acethylenedicarboxylate in the presence of indole: Theoretical and experimental investigations of the reaction mechanism

The reaction kinetics among isoquinoline, dimethyl acetylenedicarboxylate, and indole (as NH-acid) were investigated using ultraviolet (UV) spectrophotometry. The reaction rate equation was obtained, the dependence of the reaction rate on different reactants was determined, and the overall rate constant ( kov) was calculated. By studying the effects of solvent, temperature, and concentration on the reaction rate, some useful information was obtained. A logical mechanism consistent with the experimental observations was proposed. Also, comprehensive theoretical studies were performed to evaluate the potential energy surfaces of all structures that participated in the reaction mechanism. Finally, the proposed mechanism was confirmed by the obtained results and the probable and logical reaction paths and also a correct product configuration were suggested based on the theoretical results.

Synthesis of strained 1,2-diazetidines via [3 + 1] cycloaddition of C,N-cyclic azomethine imines with isocyanides and synthetic derivation

Strained diazetidines are assembled simply from 1,3-dipolar cycloaddition of isocyanides and C,N-cyclic azomethine imines, and their diversified transformations are presented.

Water mediated synthesis of 6-amino-5-cyano-2-oxo-N-(pyridin-2-yl)-4-(p-tolyl)-2H-[1,2'-bipyridine]-3-carboxamide and 6-amino-5-cyano-4-(4-fluorophenyl)-2-oxo-N-(pyridin-2-yl)-2H-[1,2'-bipyridine]-3-carboxamide - An experimental and computational studies with non-linear optical (NLO) and molecular docking analyses

6-Amino-5-cyano-2-oxo-N-(pyridin-2-yl)-4-(p-tolyl)-2H-[1,2'-bipyridine]-3-carboxamide and 6-amino-5-cyano-4-(4-fluorophenyl)-2-oxo-N-(pyridin-2-yl)-2H-[1,2'-bipyridine]-3-carboxamide were synthesized through three-component reaction between N¹,N³-di(pyridin-2-yl)-malonamide, aldehyde and malononitrile in water using triethylamine as a base at room temperature. Synthesized compounds were characterized by using different techniques (FT-IR, NMR and X-ray diffraction). Additionally, the mentioned compounds were investigated by computational chemistry methods. Obtained results were supported with calculated results. Additionally, NLO properties and molecular docking analyses of related compounds were examined in detail. The binding modes of the compounds 4a and 4b were explored with the colchicine binding site of tubulin, from molecular docking studies, remarkable interactions have been observed for 4a and 4b near to the colchicines binding site of tubulin that may contribute to the inhibition of tubulin polymerization and anticancer activity.

Construction of Fused Oxabicyclic Scaffolds from Glycals and Styrenes via One-Pot Domino Transformations

Triflic acid catalyzed cascade stereoselective reaction of glycals with styrenes delivers complex oxabicyclic scaffolds such as cis-oxadecalins or cis-cyclopentanofurans simply by tweaking the solvent. In the presence of participating solvents like benzene/toluene, cascade Ferrier C-glycosylation and double Friedel-Crafts reaction leads to densely chiral benzo-fused oxadecalins, whereas in DCM, an unprecedented ring-opening, ring-closing sequence generated cis-cyclopentanofurans. An attempt has been made to explain the above cascade sequences via intermediate trapping, kinetic experiments, and Baldwin's rules.

Convenient One-Pot Four-Component Synthesis of 6,8-Disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones via a Triple Mannich Reaction

An efficient and simple one-pot four-component protocol has been developed and performed for the synthesis of 6,8-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones, involving a triple Mannich reaction of 6-amino-2-(ethylthio)pyrimidin-4(3H)-one, formaldehyde, primary amines, and alcohols. Secondary amines were also utilised instead of alcohols as Mannich nucleophiles, and a variety of functional groups and electronically varied reaction partners were tolerated. This one-pot reaction facilitated the generation of a library of pyrimido[4,5-d]pyrimidin-4(3H)-ones in very good to excellent yields. The regioselectivity of this reaction was investigated using atomic charge calculations, and spectroscopic data confirmed that the triple Mannich products were 6,8-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones rather than the isomeric 3,6-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones. The structures of all compounds synthesised using the triple Mannich reaction were confirmed via spectroscopic and elemental analyses. The reaction mechanism was studied and confirmed by isolation of the intermediate.

Efficient and divergent synthesis of polyfunctionalized 2-pyridones from β-keto amides

Efficient and divergent one-pot synthesis of polyfunctionalized 2-pyridones from β-keto amides based on reaction condition selection was developed. The methodology offers several significant advantages including mild conditions, ease of handling, high yields, and a relatively broad range of substrates. Based on various experiments and observations, a plausible mechanism for the selective synthesis of 2-pyridones was proposed.

Multicomponent Synthesis of Tetrahydroisoquinolines

A multicomponent synthesis of tetrahydroisoquinolines from carboxylic acids, alkynyl ethers, and dihydroisoquinolines is described. This process features readily available starting materials, simple experimental procedures for achievement of molecule complexity, and structural diversity. The preliminary control experiment and crossover reaction provide important insight into the reaction mechanism. The formed tetrahydroisoquinolines could be transformed to an array of compounds.

Divergent synthesis of dual 1,4-dihydropyridines with different substituted patterns from enaminones and aldehydes through domino reactions

A concise and efficient protocol for the regioselective synthesis of dual 1,4-dihydropyridines with several substituted patterns has been developed from a cascade cyclization of enaminones and aldehydes in different media (EtOH/CH3CN). The one-pot cascade reaction involves at least five reactive sites and generates multiple C-C and C-N bonds. The established protocol explores the chemistry of enaminones by employing their three reactive sites. The method has several advantages including mild conditions, operational simplicity, and high bond-forming efficiency. It may offer promise in a variety of biochemical applications.

Ultrasound-assisted one-pot multicomponent 1,3-dipolar cycloaddition strategy: combinatorial synthesis of spiro-acenaphthylene-S,S-acetal and 2H-pyranone derivatives

The stereo/regio/chemoselective syntheses of a library of novel spiro[acenaphthylene-1,3′-pyrrolizin]-2-one and spiro[acenaphthylene-1,5′-pyrrolo[1,2-c]thiazol]-2-one have been achieved through 1,3-dipolar cycloaddition.

1,4-Conjugate addition/esterification of ortho-quinone methides in a multicomponent reaction

A novel 1,4-conjugate addition/esterification of ortho-quinone methides in a multicomponent reaction has been developed for facilely accessing 3,3-diarylpropanamides.

Nickel-catalyzed acetamidation and lactamization of arylboronic acids

A nickel-catalyzed acetamidation and lactamization of arylboronic acids via a one-pot reaction with ynamides and N-hydroxyphthalimide is described. This protocol features with mild reaction conditions and a broad substrate scope, and has been successfully applied to late-stage functionalization of pharmaceuticals. Moreover, control reactions were conducted to elucidate a plausible mechanism.

Efficient construction of C–N and C–S bonds in 2-iminothiazoles via cascade reaction of enaminones with potassium thiocyanate

Regioselective cascade reactions have been developed by using enaminones and potassium thiocyanate, offering a novel protocol for the synthesis of thiazoles from enaminones.

Synthesis of penta- and tetra-cyclic cage-like compounds and dispiro heterocycles through microwave-assisted solvent-free multi-component domino reactions

Novel penta- and tetra-cyclic cage-like compounds and dispiro heterocycles were obtained as a result of a microwave-assisted three-component domino reaction.

An efficient and rapid intramolecular cyclization of a quadruple Mannich reaction for one-pot synthesis of pentaazaphenalenes and their antimicrobial activities

An efficient, regioselective and one-pot synthesis of pentaazaphenalenes has been developed via a quadruple Mannich reaction. Most of the synthesized compounds showed significant antimicrobial activities.