Solid-phase synthesis of 1,2,3,4-tetrahydro-2-pyridones via aza-annulation of enamines

Design, synthesis and docking studies of novel thiazole derivatives incorporating pyridine moiety and assessment as antimicrobial agents

A novel series of substituted 4,6-dimethyl-2-oxo-1-(thiazol-2-ylamino)-1,2-dihydropyridine-3-carbonitrile derivatives 6, 9, 13, 15, and 17 was synthesized in a good to excellent yield from the reaction of 1-(3-cyano-4,6-dimethyl-2-oxopyridin-1(2H)-yl)thiourea with 2-oxo-N'-arylpropanehydrazonoyl chloride, chloroacetone, α-bromoketones, ethyl chloroacetate, and 2,3-dichloroquinoxaline, respectively. The potential DNA gyrase inhibitory activity was examined using in silico molecular docking simulation. The novel thiazoles exhibit dock score values between - 6.4 and - 9.2 kcal/mol and they were screened for their antimicrobial activities. Compound 13a shown good antibacterial activities with MIC ranged from 93.7-46.9 μg/mL, in addition, it shown good antifungal activities with MIC ranged from 7.8 and 5.8 μg/mL.

Reaction of β-enaminones and acetylene dicarboxylates: synthesis of substituted 1,2-dihydropyridinones

Synthesis of dihydropyridinones was achieved by reaction of β-enaminones with acetylene dicarboxylates without using transition metal/catalyst.

Infrared assisted production of 3,4-dihydro-2(1H)-pyridones in solvent-free conditions

A green approach for the synthesis of a set of ten 4-aryl substituted-5-alcoxy carbonyl-6-methyl-3,4-dihydro-2(1H)-pyridones using Meldrum’s acid has been devised, the absence of solvent and the activation with infrared irradiation in addition to a multicomponent protocol are the main reaction conditions. The transformations proceeded with moderated yields (50–75%) with a reasonable reaction rate (3 h). It is worth noting that two novel molecules of the new class of the bis-3,4-dihydropyridones were also obtained. In addition, a comparison without the use of infrared irradiation was performed.

Diastereoselective Multicomponent Synthesis of Dihydropyridones with an Isocyanide Functionality

[Structure: see text] In a search for new multicomponent strategies leading to valuable small heterocycles, a new highly diastereoselective four-component reaction (4CR) was found in which a phosphonate, nitriles, aldehydes, and isocyanoacetates combine to afford functionalized 3-isocyano-3,4-dihydro-2-pyridones. In this strategy, initially a 1-azadiene is generated, which is trapped in the same pot by an isocyanoacetate as the fourth component. Multicomponent reactions (MCRs) that lead to heterocycles containing isocyano substituents are unprecedented and offer many possibilities for further differentiation.

A diversity oriented four-component approach to tetrahydro-β-carbolines initiated by Sonogashira coupling

A consecutive four-component synthesis of highly-substituted tetrahydro-beta-carbolines can be achieved by a coupling-aminatio-aza-annulation-Pictet-Spengler (CAAPS) sequence creating five new sigma-bonds and four new stereocenters in a one-pot fashion. The structures were unambiguously supported by X-ray structure analyses.

Studies toward Labeling Cytisine with [11C]Phosgene: Rapid Synthesis of a δ-Lactam Involving a New Chemoselective Lithiation−Annulation Method

With the aim of the radiolabeling of cytisine, a potent agonist of nicotinic receptors, with [(11)C]phosgene, the rapid synthesis of a lactam model of our target has been studied. The key step of the delta-lactam formation is a new chemoselective lithiation-annulation method, under high dilution, of a suitable piperidinylcarbamoyl chloride. This precursor was obtained from (2-hydroxyethyl)piperidine in a linear synthetic sequence involving a Corey-Fuchs olefination of the corresponding aldehyde, followed by a selective reduction, using a diimide equivalent, of an iodoalkyne into a (Z)-iodopropene piperidine. This alkene served as main precursor to study the cyclization according to several procedures using phosgene as the required carbonylating reagent.

A novel one-pot four-component access to tetrahydro-β-carbolines by a coupling-amination-aza-annulation-Pictet–Spengler sequence (CAAPS)

The four-component coupling-amination-aza-annulation-Pictet-Spengler (CAAPS) sequence of acid chlorides 1, terminal alkynes 2, tryptamine derivatives 6, and acryloyl chloride derivatives 4 represents a facile and rapid one-pot access to tetrahydro-beta-carbolines 7 in moderate to good yields.

Recent developments in combinatorial organic synthesis

The level of sophistication of combinatorial synthesis continues to increase at a heady pace. Fairly complex target molecules are now being assembled combinatorially using a broad palette of organic reactions both in solution- and solid-phase. This review highlights academic and industrial examples of combinatorial synthesis published within the last year. Recent advances in small-molecule synthesis are outlined, ranging from simple acyclic scaffolds to complex natural products.

Facile enantiodivergent approach to 5-hydroxy-5,6-dihydro-2(1H)-pyridones. First total synthesis of both enantiomers of pipermethystine

[reaction: see text]. A novel enantiodivergent approach to 5-hydroxy-5,6-dihydro-2(1H)-pyridones using a ring closing metathesis and a lipase-mediated kinetic resolution as key steps is described and applied to the first synthesis of both enantiomers of pipermethystine.