Synthesis of Phosphonomethylated Bromoacetylfurans and Their Reactions with 1,3-Dicarbonyl Compounds

Bromination of (diethoxyphosphorylmethyl)acetylfurans with dioxane dibromide in the mixture of chloroform and acetic acid in presence of traces of hydrogen bromide at room temperature proceeds selectively at the methyl group of ketone does not involving phosphonate group. Obtained bromoacetyl derivatives were used for alkylation of acetoacetic ester and cyclohexan-1,3-dione. Reaction of 1,4-diketone prepared from acetoacetic ester with hydrazine hydrate in ethanol at room temperature leads to formation of furylpyrazines due to aromatization of intermediate azines by means of air oxygen.

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

The three-component reaction of 5-aminotetrazole with aliphatic aldehydes (formaldehyde, acetaldehyde) and acetoacetic ester derivatives in water under microwave irradiation leads to the selective formation of 4,7-dihydrotetrazolo[1,5-a]pyrimidine derivatives. Under similar conditions using 4,4,4-trifluoroacetoacetic ester 5-hydroxy-4,5,6,7-tetrahydrotetrazolo[1,5-a]pyrimidines are obtained. The analogous reaction with acetylacetone requires scandium(III) triflate as catalyst. The antioxidant activity of selected compounds was assayed with 1,1-diphenyl-2-picrylhydrazyl.

Preparation and Properties of Acetoacetic Ester-Terminated Polyether Pre-Synthesis Modified Phenolic Foam

In the present study, acetoacetic ester-terminated polyether was selected as a modifier to prepare a new type of polyether phenolic resin, which was successfully prepared by pre-synthesis modification. It is used to prepare interpenetrating cross-linked network structure modified phenolic foam with excellent mechanical properties. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H NMR, 13C NMR) were used to characterize the molecular structure of the polyether phenolic resin. The results showed that the acetoacetic ester-terminated polyether successfully modified the phenolic resin and introduced a polyether skeleton into the resin structure. The effect of changing the added amount of acetoacetic ester-terminated polyether from 10% to 20% of the phenol content on the mechanical properties and microstructure of the modified phenolic foam was investigated. The results showed that when the amount of acetoacetic ester-terminated polyether was 16% the amount of phenol, this resulted in the best toughness of the modified foam, which had a bending deflection that could be increased to more than three times that of the base phenolic foam. The modified phenolic foam cell diameter was reduced by 36.3%, and the distribution was more uniform, which formed a denser network structure than that of the base phenolic foam. The bending strength was increased by 0.85 MPa, and the pulverization rate was as low as 1.3%.

Synthesis of substituted pyrrolo[2,3-d]pyrimidines and pyrido[2,3-d]pyrimidines in the one-pot condensation of 2-thio-6-aminouracil, arylglyoxals and CH-acids

We have developed some available and effective methods for the synthesis of substituted pyrrolo[2,3-d]pyrimidines and 5,8-dihydropyrido[2,3-d]pyrimidines based on the three-component condensation of 6-amino-2-thiouracil with arylglyoxal hydrates and N,N-dimethylbarbituric acid or acyclic β-dicarbonyl compounds: acetylacetone (acetoacetic ester). It was shown that the optimal product yields were obtained by boiling the reagents in acetic acid. Thus, the synthesis of pyrrolo[2,3-d]pyrimidines took 15-20 minutes, while the precipitation of 5,8‑dihydropyrido[2,3-d]pyrimidines formed only after 2 hours. We proposed possible mechanisms for the formation of anelated pyrrole and pyridine rings. In both cases, the reaction includes the formation of an intermediate of α,β-unsaturated ketone with the participation of arylglyoxal and CH-acid (N,N-dimethylbarbituric or acetylacetone (acetoacetic ester)), nucleophilic addition of 6-aminothiouracil via an activated double bond, condensation of carbonyl and amino groups. The formation of the cycle takes place exclusively with the participation of the acetyl moiety, while the pyrrol one forms during the condensation of the aroyl moiety and the 6-amino group of thiouracil. A series of synthesized pyrrolo[2,3-d]pyrimidines was modified by alkylation. As it was expected, alkylation proceeds at the sulfur atom, that allowed a significant increase in the solubility of the obtained products. The reaction was carried out in DMF by stirring the initial reagents at 60ºC (reaction with methyl iodide) or boiling them (alkylation with phenacyl bromide), whereby S-methyl and S-phenacyl derivatives of pyrrolo[2,3-d]pyrimidines were obtained. The spectral data of 1H NMR showed that S-methylation products form solvates with DMF as 1:1. The synthesized compounds can become the basis to create small libraries of anelated pyrimidines with improved antiviral activity profile.

Convenient Synthesis of Ethyl 5-Oxohomoadamantane-4-carboxylate: A Useful Precursor of Polyfunctional Homoadamantanes

A facile and convenient synthesis of ethyl 5-oxohomoadamantane-4-carboxylate is reported, and its chemical properties as a cage analogue of acetoacetic ester are investigated. Various derivatives of homoadamantane were synthesized through the reaction of 5-oxohomoadamantane-4-carboxylate with electrophilic agents, binucleophiles, and hydrazoic acid. Some new unusual products were obtained by the reaction of that β-keto ester with nitric acid and nitrosyl chloride. Cage compounds synthesized could be used as precursors for the diverse condensed heterocyclic compounds with potential viral ion channel abrogating activity that possess conformationally rigid lipophilic moieties.