Nanocomposites Based on Poly(Amide-Imide) Matrix with Na–Mg Triple Chain Hydrosilicate

Crystallography Reports - A new polymer-inorganic nanocomposite composed of fibrous Na–Mg triple chain hydrosilicate with a poly(amide-imide) matrix was developed. Its structure, morphology,...     

Zn(OTf)2-catalyzed,microwave-promoted synthesis of 2-substituted 5-methyloxazoles from propargylic amides

The versatile conversion of propargylic amides to the respective 2-substituted 5-methyloxazoles was efficiently catalyzed by Zn(OTf)₂ (5?mol%) under microwave irradiation in toluene. The method was applicable to a wide range of aliphatic, aromatic and heteroaromatic propargylic amides and thus represents a useful method which is complementary to the existing metal-catalyzed protocols, considering the ready availability of Zn(OTf)₂.     

Relaxation processes in an aromatic polyamide-imide and composites on its basis with hydrosilicate nanoparticles

Features of the relaxation behavior of an aromatic polyamide-imide and a composite with nanotubes of magnesium silicate with the structure of chrysotile have been studied by dynamic mechanical analysis, dielectric spectroscopy, and differential scanning calorimetry. Two secondary relaxation (β₁ and β₂) transitions have been found, the activation energies of these processes have been determined, and the solvent effect on the cooperativeness degree has been studied. Changes in the value of the apparent activation energy of the β₁-process caused by the subsequent heating of polymeric and composite samples have been analyzed according to the Starkweather procedure. It has been shown that, as the solvent is released from the polyamide-imide film, the polymer exhibits increasing local mobility, which are predetermined by the structure of the molecular unit. Using the GAMESS software, we have assumed the most probable dimer conformations that correspond to two repeating units of the polyamide-imide molecule.     

An expeditious and atom-economic synthesis of lead-like,medicinally important 4,5-dihydropyrazolo[1,5-a]pyrazin-6-ones

We have developed an expeditious and atom-economic synthesis of lead-like, privileged 4,5-dihydropyrazolo[1,5-a]pyrazin-6-ones, which is based on Sonogashira coupling and a two-step condensation with hydrazine hydrate leading to two ring-forming events, with full control over the two elements of diversity present.     

Antiviral drug nevirapine as a template for hydrated imidazoline ring expansion (HIRE): Rapid access to the diarene-fused 1,4,7-triazecine ring system

The tricyclic ring system of the antiviral drug nevirapine has been employed to test the workability of the hydrated imidazoline ring expansion (HIRE) reaction which was previously exemplified for [1.4]oxazepine and [1.4]thiazepine counterparts. The imidazoline nucleus was grafted onto the lactam moiety of nevirapine in two high-yielding steps. Subsequent N-alkylation and the HIRE reaction proceeded as envisioned and delivered rare ring-expanded diarene-fused 1,4,7-triazecines with a diversity of alkyl substituents at the lactam nitrogen atom. These findings extend the scope of the HIRE reaction to the medicinally prominent [1.4]diazepine chemical space.     

Xth International Conference of Young Scientists in Chemistry “Mendeleev-2017.” Section “Bioorganic and Medicinal Chemistry”

Russian Journal of Organic Chemistry -     

New tetracyclic 1,4-oxazepines constructed via practically simple tandem condensation strategy from readily available synthons

A streamlined synthetic methodology towards novel tetracyclic 1,4-oxazepines from readily available precursors is described. The compounds, designed as more soluble version of the earlier described, poorly soluble dibenzo[b,f][1,4]oxazepines, were obtained in high yields and as a single regioisomer as a result of three tandem chemical events—nucleophilic aromatic substitution, Smiles rearrangement and denitrocyclization.     

Synthesis of N-substituted pyrido[3,2-b][1,4]benzothiazepin-(11H)-one derivatives by denitrocyclisation reaction

A new approach to the synthesis of N-substituted pyrido[3,2-b][1,4]benzothiazepin-10(11H)-one derivatives from 2-chloro-3-nitropyridine and thiosalicylic acid using denitrocyclisation reaction for the tricycle-system formation is proposed.