Synthetic Communications最新文献

The present work developed a new simple method and convenient procedure to synthesize a novel series of 1-(4,6-dimethylpyrimidin-2-yl)-2-imino-3-arylimidazolidin-4-ones 3. The sodium salt of N-(4,6-dimethylpyrimidin-2-yl)cyanamide (1) was selected to use as the starting material to undergo intramolecular cyclization reaction with 2-chloro-N-arylacetamides in boiling acetone for about 12–18 hours. According to this new synthetic route, eleven imino-hydantoins were readily separated in moderate to excellent yields as single products after cooling the reaction without any purification technique. Also, on the basis of the experimental results and analysis data (IR, NMR, elemental analyses, and GC-MS spectra), the reaction is regiospecific as well as a plausible mechanism to form the target products 3 instead of di-imino-oxazolidines 4 and/or 2-imino-2,3-dihydro-oxazoles 5 is proposed.

5-Alkylated barbituric acids are an important class of compounds that constitute the basic moiety of several clinically used hypnotic drugs. Here we report a catalyst-free domino Knoevenagel-Michael addition involving barbituric acid, aldehyde, and N,N-disubstituted aniline in solvent acetonitrile to synthesize 5-alkylated barbituric acid derivatives (72–94% yield) without using any chromatographic separation techniques. The C-4 position of aniline acts as the Michael donor. All the reactions are successfully performed without catalysts, providing an environment-friendly and economical route for the synthesis. Moreover, catalyst-free reactions are less sensitive to air and moisture unlike many metal catalysts, with easy separation of products, and simple operating procedures as there is no need for catalyst weighing, recovery, and removal. A plausible mechanism is also proposed based on control experiments.

Ionic liquids were known as eco-solvents/catalysts, encourages the clean hydrophosphonylation of aldehydes to produce structurally various α-hydroxyphosphonates in a well-organized and ecologically friendly manner. This study used tetrabutylammonium hydroxide (TBAH) used to addition phosphite nucleophiles to aldehydes under neat condition, resulting in different α-hydroxyphosphonates that are essential components of the modern chemical industry. The current method produces targeted compounds from a wide range of aromatic, and heteroaromatic aldehydes with various substitution. The current protocol has high impact because it allows for the formation of desired products in good yields. This catalyst is applicable for gram scale synthesis of the targeted product and without any additional energy (Microwave, ultrasonication, ball milling and thermal heating). Some reported methods used various external sources (mechano-chemical) for the synthesis of α-hydroxyphosphonates.

A six-membered heterocyclic compound known as piperazine has two nitrogen atoms within a ring. Numerous studies have shown that piperazine has the potential to be a useful pharmacophore in many harmful pharmacological conditions, such as microbiocidal, anti-inflammatory, anticancer, antioxidant, etc. In this present review, we highlighted the synthetic protocols for piperazine and its analogs and the synthetic protocol for piperazine via rearrangement reactions that have been adopted in recent years. The study also involved a listing of several patents (granted), which comprised important work on piperazine and its derivatives. Among all the methods, the most commonly adopted synthetic methods included the synthesis of piperazine analogs by diaza-cope, hydrolytic, Mumm, Ugi-smiles, [2 + 3] Stevens, Aza-witting, Curtius, Schmidt rearrangement reactions, etc. These synthetic protocols have also been compared based on different reaction conditions, feasibility, and economy to help the researchers in designing their work.

Under ambient temperature conditions, a novel method has been developed for the conversion of aryl bromides to aromatic aldehydes, utilizing DMF (N,N-dimethylformamide) as both the starting material and solvent, in the presence of samarium metal and a trace of silver salts. This research has successfully explored an efficient approach for Barbier-type addition reactions, leading to the establishment of a novel C-C bond. A variety of bromides have been investigated as substrates, and aldehydes are readily obtained in moderate to high yields under mild conditions. The presence of 1 mol% of silver nitrate and potassium iodide is sufficient to catalyze the reaction, with the primary role of potassium iodide being to generate soluble silver iodide in the organic solvent, thereby catalyzing the reaction. The mechanism of the silver(I)-catalyzed process is discussed.

We report two methods for selective morpholinomethylation and formylation of C1 − H bonds in pyrrolo[1,2-a]quinoxalines. Reaction of pyrrolo[1,2-a]quinoxalines and morpholine using CuI catalyst, (bis(trifluoroacetoxy)iodo)benzene oxidant, and DMSO solvent yielded the morpholinomethylation products. Meanwhile, formylation of C1 − H bonds in pyrrolo[1,2-a]quinoxalines progressed in the presence of CuI catalyst, trifluoroacetic acid, and DMSO solvent. Compounds bearing halogen, methylsulfonyl, pyridine, and thiophene groups were isolated in moderate yields.

A series of 4-hydroxy-6-methyl-3-(1-(4-(aryl/methyl)thiazol-2-yl)-1H-pyrazol-3-yl)-2H-pyran-2-ones 3a–h have been synthesized from aryl/methyl halomethylketones and a key pyrazole intermediate 1 using a convenient one-pot synthesis method. All compounds were characterized by NMR and MS, and the structure of three of them (3a, 3b and 3f) was resolved by X-ray diffraction. These heteroatom-rich thiazole compounds were then evaluated as inhibitors of Mycobacterium tuberculosis InhA, a key enzyme involved in the type II fatty acid biosynthesis pathway of the mycobacterium. Although inhibitory activities were found to be rather weak, molecular docking studies were also been carried out to understand a possible mode of interaction with key residues in the enzyme’s active site.

The biocompatibility, specificity, and consistency of natural carbohydrate polymers in catalyzing organic processes have garnered significant interest. For the production of organic compounds, a variety of carbohydrate polymers have been employed as heterogeneous catalysts, including agarose, cellulose, chitosan, chitin, sodium alginate, carrageenan, dextrin, starch, and pectin. This article provides an overview of several straightforward and efficient techniques for the mild reaction conditions catalytic synthesis of organic compounds employing carbohydrate polymers as the source of heterogeneous catalytic species.

This study presents a novel and rare demethylation of 4-benzylidene-2-phenyloxazolones under NaOH/EtOH/H₂O conditions. The potential mechanism underlying the phenomenon was evaluated through control reactions.

Concise route for the synthesis of (-)-isoaltholactone and (±)-5-epi-OBn-Goniotriol were described. Key features for the (-)-isoaltholactone synthesis involved; a) diastereoselective and enantioselective aldol reaction between chiral pyrrolidine substituted γ-benzyloxy vinylogous urethane enolate and cinnamaldehyde afforded highly stereoselective syn δ-lactone, b) allylic 1,3-strain controlled epoxidation of styryl alkene following the stereospecific opening of the epoxide assisted by a proximal benzyloxy group completed the synthesis. Reaction of simple pyrrolidine substituted γ-benzyloxy vinylogous urethane enolate and cinnamaldehyde gave anti δ-lactone. Epoxidation and epoxide opening of the styryl alkene substrate of anti δ-lactone derivative was also investigated, which led to the synthesis of (±)-5-epi-OBn-Goniotriol.