10.1016/j.tetlet.2011.11.125
The research focuses on highly efficient thermal cyclization reactions of alkylidene esters in a continuous flow reactor system, aiming to synthesize aromatic and heteroaromatic derivatives. The study was conducted at temperatures ranging from 300–360°C and under high pressure conditions (100–160 bar) with short residence times (0.45–4.5 min) in tetrahydrofuran as a solvent. The process resulted in the synthesis of substituted heteroaromatic compounds, including pyridopyrimidinones and hydroxyquinolines, as well as naphthol and biphenyl derivatives, in moderate to high yields. The continuous flow methodology offered advantages such as ease of work-up, suitability for automation, and scalability, and was considered a greener alternative due to the use of a low-boiling point solvent that can be recycled, reducing waste. The chemicals used in the process included alkylidene b-diesters, Meldrum’s acid, malonic ester, cyanoacetic acid esters, and various amines for the synthesis of the precursors and the cyclization reactions.
10.1016/j.bmcl.2009.08.013
The research aims to develop new quinolinone compounds with potential antiparasitic and anti-HIV activities using an innovative two-step synthesis method involving microwave irradiation. The study evaluates these compounds against Plasmodium falciparum, Leishmania donovani, Trichomonas vaginalis, and HIV. Key chemicals used include various Meldrum's acid derivatives synthesized from different aminoheterocycles and nitroanilines. The microwave irradiation method allowed for efficient synthesis with good yields (39–92%) and reduced reaction times. The results showed that most compounds were not cytotoxic, and some exhibited moderate antimalarial and anti-HIV activities. Notably, compound 1k demonstrated activity against both malaria and HIV with low cytotoxicity and a high specificity index. The study concludes that this microwave-assisted synthesis method is effective for creating new quinolinone structures with potential therapeutic applications, and further research is needed to optimize the structures for enhanced activity and reduced toxicity.
10.1016/j.tetlet.2018.11.065
The study presents a novel method for synthesizing α, β-unsaturated ketones using a dual cooperative organocatalytic approach. The key chemicals involved in this study are acetone and various aldehydes (both aromatic and aliphatic) which serve as the starting materials. The reaction is catalyzed by N,N-dimethylethylene diamine (DMEDA) and Meldrum’s acid. DMEDA plays a crucial role in forming an enamine intermediate with acetone, while Meldrum’s acid facilitates the Knoevenagel condensation with the aldehyde. The process involves a domino Knoevenagel-Michael-retro Michael reaction sequence, occurring in a one-pot setup at 55 °C for 24 hours in ethyl acetate solvent. The method is notable for its high E-selectivity and regioselectivity, yielding α, β-unsaturated ketones with excellent purity and no significant side products from self-condensation. The study demonstrates the practicality and efficiency of this approach by synthesizing a total of 23 different α, β-unsaturated ketones, showcasing the versatility and applicability of the dual cooperative catalysis method in organic synthesis.
10.1248/cpb.38.3230
The research presents the first asymmetric total synthesis of (+)-hirsutic acid in a highly stereocontrolled manner. The synthesis includes a novel method for the preparation of (1S,5R,6S)-6-hydroxy-cis-bicyclo[3.3.0]octan-3-one and a stereospecific Simmons-Smith reaction controlled by the participation of a relatively remote hydroxyl group. Key chemicals involved in the research include methyl (1R,5R)-5-phenoxythiocarbonyl-2-cyclopentenylacetate, (S)-2-cyclopentenylacetic acid, methyl (S)-3-oxo-4-(2-cyclopentenyl)butyrate, and various reagents such as tributyltin hydride, thionyl chloride, Meldrum's acid, and pyridine. The synthesis process involves multiple steps, including reduction, hydrolysis, esterification, and oxidation, with careful control of reaction conditions to achieve the desired stereochemistry and yield of the final product, (+)-hirsutic acid.
10.1055/s-0028-1087279
The study presents a novel one-pot, three-component synthesis of ?-amino acids using 2-aminopyridines, aldehydes, and Meldrum’s acid in an alkaline aqueous solution. This method leverages water as a green solvent, offering environmental benefits and cost-effectiveness. The reaction involves condensing a 2-aminopyridine with an aldehyde to form an aldimine intermediate, which is then attacked by the enol tautomer of Meldrum’s acid. Subsequent nucleophilic addition of water and elimination of acetone and carbon dioxide yield the desired ?-amino acids. The process is efficient, yielding products in 74–98% yields within 1.5 hours, and is particularly advantageous for synthesizing aromatic aldehydes. The simplicity and high yields make this method a promising alternative for ?-amino acid synthesis, which has applications in pharmaceuticals and natural products.
10.3184/174751917X14839766277251
In the research, Meldrum's acid (isopropylidene malonate) is described as a versatile reagent with significantly stronger acidity compared to its corresponding acyclic malonates. This enhanced acidity is crucial for its reactivity in various chemical transformations. Meldrum's acid serves as the starting material for the synthesis of 5-monosubstituted derivatives, which are then used to generate Mannich bases. These Mannich bases can readily undergo condensation reactions with nitroalkanes under mild conditions, facilitated by a weak acid catalyst. The study highlights Meldrum's acid's ability to participate in one-pot tandem reactions, where it reacts with an aminomethylating agent and nitroalkanes to produce nitroalkyl derivatives. The specific structure of Meldrum's acid allows for the formation of stable intermediates and products, such as the Mannich bases and their subsequent condensation products. The research also notes that the reactivity and outcomes of these reactions are influenced by the substituents on Meldrum's acid and the nitroalkanes, demonstrating the importance of Meldrum's acid's structural versatility in achieving the desired products.
10.1021/cc100032d
The study presents a novel one-pot multicomponent reaction for the synthesis of tetrahydrobenzo[b][1,4]oxazepine and malonamide derivatives. The reaction involves 2-aminophenols, Meldrum’s acid, and isocyanides, and it proceeds at ambient temperature with good to excellent yields. These chemicals serve to create a new class of substituted malonamide and tetrahydrobenzo[b][1,4]oxazepine derivatives, which are significant in medicinal chemistry due to their potential as ionophores for selective electrodes, liquid-liquid extractants for nuclear waste management, and pharmaceutical compounds with diverse biological activities, including anticancer properties.
10.1021/acs.orglett.7b01225
The study presents a diastereoconvergent synthesis of spirocyclic endoperoxides using a Meldrum’s acid scaffold. The key chemicals involved include Meldrum’s acid derivatives, ethyl acetoacetate, and a Cu(II) catalyst. Meldrum’s acid alkylidene reacts with the sodium enolate of ethyl acetoacetate to form Michael adducts, which are then oxidized by elemental oxygen under the catalysis of Cu(II) to produce endoperoxides. These endoperoxides undergo hydrogenolysis to yield spirocyclic hemiketals, which are further reduced by Lewis acids to form highly substituted tetrahydrofurans. The study highlights the chemoselective aerobic oxidation and sequential reductions that enable the creation of complex tetrahydrofuran structures from simple feedstock chemicals, with high yields and diastereoselectivity.
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