An efficient synthesis of 4,5-disubstituted-2H-1,2,3-triazoles from nitroallylic derivatives via a cycloaddition–denitration process

A variety of nitroallylic derivatives were smoothly reacted with sodium azide in the presence of p-TsOH to form synthetically-viable triazoles.

Multicomponent access to androstano-arylpyrimidines under microwave conditions and evaluation of their anti-cancer activity in vitro

Novel ring D- and A-fused pyrimidines in the androstane series were efficiently synthesized within 10-15min in polar protic solvents under microwave irradiation via two kinds of multicomponent heterocyclization reactions followed by spontaneous or promoted oxidation. The rates of the one-pot catalyst-free transformations of steroidal β-ketoaldehydes, ammonium acetate and substituted benzaldehydes in EtOH were found to be affected slightly by the steric and electronic feature of the substituents on the aromatic ring of the arylaldehyde component and the different reactivities of rings D and A of the sterane core. At the same time, the acid-catalyzed Biginelli-type reaction of dihydrotestosterone acetate, urea and arylaldehydes, and subsequent Jones oxidation of the primarily formed dihydropyrimidinones led to the corresponding ring A-fused 1H-pyrimidin-2-ones in moderate yields independently of the substituents on the aromatic moiety. The synthesized compounds were tested in vitro on human cancer cell lines as well as on non-cancerous fibroblast cells by the MTT assay in order to investigate their biological effects. As a result of the pharmacological screen, a remarkable structure-function relationship has been observed as the acetylated Biginelli products exhibited higher toxicity compared to the deacetylated version of each compound. Furthermore, in case of three 2'-arylpyrimidine derivatives a strong prostate cancer cell specific activity has been identified.

Stereoselective Coupling of N-tert-Butanesulfinyl Aldimines and β-Keto Acids: Access to β-Amino Ketones

The reaction of chiral N-tert-butanesulfinyl aldimines with β-keto acids under basic conditions at room temperature proceeds with high levels of diastereocontrol, leading to β-amino ketones in high yields. Based on DFT calculations, an eight-membered cyclic transition state involving coordination of the lithium atom to the oxygens of carboxylate and sulfinyl units was proposed, being in agreement with the observed experimental diastereomeric ratios. The synthesis of the piperidine alkaloid (-)-pelletierine was successfully undertaken in order to demonstrate the utility of this methodology.

Synergy Effects in the Chemical Synthesis and Extensions of Multicomponent Reactions (MCRs)-The Low Energy Way to Ultra-Short Syntheses of Tailor-Made Molecules

Several novel methods, catalysts and reagents have been developed to improve organic synthesis. Synergistic effects between reactions, reagents and catalysts can lead to minor heats of reaction and occur as an inherent result of multicomponent reactions (MCRs) and their extensions. They enable syntheses to be performed at a low energy level and the number of synthesis steps to be drastically reduced in comparison with ‘classical’ two-component reactions, fulfilling the rules of Green Chemistry. The very high potential for variability, diversity and complexity of MCRs additionally generates an extremely diverse range of products, thus bringing us closer to the aim of being able to produce tailor-made and extremely low-cost materials, drugs and compound libraries.

Synthesis of structurally diverse 3,4-dihydropyrimidin-2(1H)-ones via sequential Biginelli and Passerini reactions

The Biginelli reaction was combined with the Passerini reaction for the first time in a sequential multicomponent tandem reaction approach. After evaluation of all possible linker components and a suitable solvent system, highly functionalized dihydropyrimidone-α-acyloxycarboxamide compounds were obtained in good to excellent yields. In a first reaction step, different 3,4-dihydropyrimidin-2(1H)-one acids were synthesized, isolated and fully characterized. These products were subsequently used in a Passerini reaction utilizing a dichloromethane/dimethyl sulfoxide solvent mixture. By variation of the components in both multicomponent reactions, a large number of structurally diverse compounds could be synthesized. In addition, a one-pot Biginelli-Passerini tandem reaction was demonstrated. All products were carefully characterized via 1D and 2D NMR as well as IR and HRMS.

Synthesis of amphiphilic fluorescent polymers via a one-pot combination of multicomponent Hantzsch reaction and RAFT polymerization and their cell imaging applications

A novel one-pot strategy for the fabrication of AIE-based FONs was developed via the combination of RAFT polymerization and the Hantzsch reaction for the first time.

High-throughput polymer screening in microreactors: boosting the Passerini three component reaction

The Passerini three-component reaction (Passerini-3CR) has been studied via on-line microreactor/electrospray ionisation mass spectrometry (MRT/ESI-MS) reaction monitoring to demonstrate the high-throughput screening potential of microreactors for macromolecular design.

Efficient Ugi reactions in an aqueous vesicle system

A new, alternative route for the synthesis of a variety of α-aminoacyl amides via the four-component Ugi reaction in the presence of different surfactants in aqueous solution was investigated. High reaction yields were obtained in many cases with vesicles formed from DDAB.

A new paradigm for designing ring construction strategies for green organic synthesis: implications for the discovery of multicomponent reactions to build molecules containing a single ring

A new way of developing novel synthesis strategies for the construction of monocyclic rings found in organic molecules is presented. The method is based on the visual application of integer partitioning to chemical structures. Two problems are addressed: (1) the determination of the total number of possible ways to construct a given ring by 2-, 3-, and 4-component couplings; and (2) the systematic enumeration of those possibilities. The results of the method are illustrated using cyclohexanone, pyrazole, and the Biginelli adduct as target ring systems with a view to discover new and greener strategies for their construction using multicomponent reactions. The application of the method is also extended to various heterocycles found in many natural products and pharmaceuticals.

Multicomponent reactions of phosphines, enynedioates and benzylidene malononitriles generated highly substituted cyclopentenes through an unexpected phosphine α-addition-δ-evolvement of an anion pathway

Multicomponent reactions of phosphines, enynedioates and benzylidene malononitriles provide highly substituted syn-selective cyclopentenes appending the phosphorus ylide moiety in good yield with a diastereoselectivity of up to 100% through resonance-derived 1,5-dipolar species as the key intermediates, via the nucleophilic α(δ')-attack of phosphines toward enynedioates followed by addition to benzylidene malononitriles and 5-exo-dig cyclization. Through computational analyses, the overall reactions for the formation of syn- and anti-diastereomers are both exothermic with 65.6 and 66.3 kcal mol(-1) at the B3LYP-D3/6-31G(d) level of theory and were found to be kinetically controlled, which favours the formation of syn-diastereomers.

Unexpected isocyanide-based three-component bicyclization for the stereoselective synthesis of densely functionalized pyrano[3,4-c]pyrroles

A novel three-component bicyclization strategy for the efficient synthesis of densely functionalized pyrano[3,4-c]pyrroles has been established from readily accessible 3-aroylacrylic acids, dialkyl acetylenedicarboxylates and isocyanides. The reaction pathway involves Huisgen 1,3-dipole formation, Passerini-type reaction, Mumm rearrangement and an oxo-Diels-Alder reaction sequence, resulting in continuous multiple bond-forming events including C-N, C-O and C-H bonds to rapidly build up molecular complexity.

Eu2O3 modified CeO2 nanoparticles as a heterogeneous catalyst for an efficient green multicomponent synthesis of novel phenyldiazenyl-acridinedione-carboxylic acid derivatives in aqueous medium

Synthesis of phenyldiazenyl-acridinedione-carboxylic acids by a one-pot multicomponent coupling of 1,3-dicarbonyl compounds, substituted-phenyl-diazenyl-benzaldehydes and glycine using Eu₂O₃ modified CeO₂ as the catalyst in aqueous medium.

Evaluation of sodium acetate trihydrate–urea DES as a benign reaction media for the Biginelli reaction. Unexpected synthesis of methylenebis(3-hydroxy-5,5-dimethylcyclohex-2-enones), hexahydroxanthene-1,8-diones and hexahydroacridine-1,8-diones

In this work, the low melting mixture sodium acetate trihydrate–urea was synthesized and the eutectic composition was determined and characterized. The performance of this deep eutectic solvent on the Biginelli reaction was evaluated.

Synthesis of benzoimidazoquinazolines by cobalt-catalyzed isocyanide insertion–cyclization

The synthesis of benzoimidazoquinazoline amines by the reaction of isocyanides and benzo[d]imidazol-anilines via a cobalt-catalyzed isocyanide insertion reaction into the two N–H active bonds is reported.

In situ generation and protonation of the isocyanide/acetylene adduct: a powerful catalyst-free strategy for multicomponent synthesis of ketenimines, aza-dienes, and heterocycles

In addition to isocyanide-based Ugi, Passerini, van Leusen, and Orru multicomponent reactions, a new class of isocyanide/acetylene-based multicomponent reactions, using zwitterionic adducts, have emerged as powerful methods to synthesize biologically interesting molecules.

Meglumine catalyzed one-pot, three-component combinatorial synthesis of pyrazoles bearing a coumarin unit

Meglumine has been found to be an efficient catalyst for the synthesis of pyrazolylcoumarins by one-pot three-component reaction of salicylaldehyde, 4-hydroxy-6-methyl-2H-pyran-2-one, and hydrazine.

An efficient green protocol for the preparation of acetoacetamides and application of the methodology to a one-pot synthesis of Biginelli dihydropyrimidines. Expansion of dihydropyrimidine topological chemical space

A one pot synthesis of Biginelli dihydropyrimidines. The novel use of the amino acids allows topological diversification of the chemical space.