[3+2] Cycloaddition of Alkynyl Boronates and in situ Generated Azomethine Ylide.

Scalable [3+2] cycloaddition of alkynyl boronates and in situ generated unstabilized azomethine ylide is reported for the first time. The selective formation of either 1 : 1 or 1 : 2 cycloaddition products was achieved by carefully optimizing the reaction conditions, mainly by controlling the reactant stoichiometry, catalyst loading, and internal temperature. The developed protocol tolerated many valuable functional groups, including TMS, protected alcohol (as ether or THP derivatives), or aldehyde (as acetal).

Photochemical [2+2] Cycloaddition of Alkynyl Boronates.

A photochemical [2+2] cycloaddition of alkynyl boronates and maleimides is reported. The developed protocol provided 35-70 % yield of maleimide-derived cyclobutenyl boronates and demonstrated wide compatibility with various functional groups. The synthetic utility of the prepared building blocks was demonstrated for a range of transformations, including Suzuki cross-coupling, catalytic or metal-hydride reduction, oxidation, and cycloaddition reactions.

2-Azahetaryl-2-(oxoindolin-2-ylidene)acetonitriles as Colorimetric Probes for Zn: Synthesis and Optical Properties.

A new one-pot approach for the synthesis of the Zn-sensitive probes 2-azahetaryl-2-(oxoindolin-2-ylidene)acetonitriles and is described. The method includes the formation of imidoylchloride and its further condensation with azahetarylacetonitrile . The structure of the obtained compounds is studied using H nuclear magnetic resonance (NMR), C NMR, infrared (IR), high-resolution mass spectrometry (HRMS), and UV-Vis spectroscopy techniques.

Synthesis of 3-Borylated Pyrrolidines by 1,3-Dipolar Cycloaddition of Alkenyl Boronates and Azomethine Ylide.

A scalable and efficient process for the preparation of 3-borylated pyrrolidines by 1,3-dipolar cycloaddition of N-benzyl azomethine ylide generated in situ has been developed. The optimized method included the use of LiF in DMSO at 110 °C and was suitable for α-mono-, α,β-di-, and α,β,β-trialkyl-, β,β-(hetera)cycloalkylidene-, CO Et-, as well as most β-(het)aryl-substituted alkenyl boropinacolates. The 1,3-dipolar reaction proceeded on a multigram scale providing 3-borylated pyrrolidines with diverse substitution patterns (including fused and spirocyclic ones) in a diastereoselective manner.

Synthesis of spirocyclic β- and γ-sultams by one-pot reductive cyclization of cyanoalkylsulfonyl fluorides.

One-pot intramolecular cyclization of novel sp-enriched cyanoalkylsulfonyl fluorides into spirocyclic β- or γ-sultams is disclosed. The method relies on nitrile group reduction followed by sulfonylation of amino group thus formed upon mild conditions (NaBH, NiCl·6HO in MeOH). Cyclization proceeds smoothly with considerable efficiency (48-84%, 10 examples) on up to 30 g scale.

Synthesis and biological activity of 4-amino-3-chloro-1-pyrrole-2,5-diones.

4-Amino-3-chloro-1-pyrrole-2,5-dione derivatives were designed and synthesized as potential tyrosine kinase inhibitors. One of them has been shown to inhibit growth of cancer cell lines and in vivo tumors. To determine the impact of side groups on biological activity the ability of different 4-amino-3-chloro-1-pyrrole-2,5-diones to interact with ATP-binding domains of growth factor receptors and with model cell membranes were aimed to be discovered.

4-Amino-2,3-dihydro-1λ-isothiazole-1,1-dioxides and their chemical properties evaluation.

The reactivity of the 4-amino-2,3-dihydro-1H-1λ-isothiazole-1,1-dioxide (β-amino-γ-sultam) framework has not been studied sufficiently. Here we describe the chemical properties of this heterocyclic system toward electrophiles on spiranic and non-spiranic substrates. A variety of C-electrophiles (acetic anhydride, benzoyl chloride, DMFDMA, 4,4-dimethoxybutan-2-one) and heteroatom electrophiles (bromine, nitrosyl acetate) have been explored.

Enhanced π-frustration in carbo-benzenic chromophores.

The synthesis, structure, and absorption spectra of highly π-frustrated carbo-benzenes with indolic enamine substituents more or less directly conjugated to the C18 macro-aromatic core are described, and their peculiar reactivity is analyzed.

High throughput synthesis of extended pyrazolo[3,4-d]dihydropyrimidines.

Thirteen 5-hetarylaminopyrazoles were synthesized in 62-93% yield through the arylation of 1-isopropyl- and 1-phenyl-5-aminopyrazoles with electrophilic hetarylhalides under optimized conditions. Condensation of 5-hetarylaminopyrazoles with carbonyl compounds facilitated by AcOH or Me(3)SiCl furnished 23 pyrazolo[3,4-d]dihydropyrimidines in 69-86% yield. The target compounds were isolated through simple crystallization.

14-(2,3-Dichloro-phen-yl)-9,10-dimethyl-benzimidazo[1,2-a]benzo[f][1,8]naphthyridine-6-carbonitrile.

In the title compound, C(27)H(16)Cl(2)N(4), the benzimidazo[1,2-a]benzo[f][1,8]naphthyridine system is nearly planar (r.m.s.

10-Methoxy-benzo[g]imidazo[1,2-a][1,8]naphthyridine-4-carbonitrile.

In the title compound, C(16)H(10)N(4)O, both the meth-oxy and nitrile substituents lie in the plane defined by the benzo[g]imidazo[1,2-a]-1,8-naphthyridine ring system, resulting in a nearly planar geometry for the entire mol-ecule (r.m.s.

Aromaticity-controlled tautomerism and resonance-assisted hydrogen bonding in heterocyclic enaminone-iminoenol systems.

The contribution of aromaticity and intramolecular hydrogen bonding to relative stability, for a set of (1H-azahetero-2-ylidene)-acetaldehyde and 2-azahetero-2-yl-ethanol tautomeric pairs, has been investigated by means of quantum chemical DFT and ab initio methods up to the MP4(SDTQ)/AUG-cc-pVDZ and MP2/AUG-cc-pVTZ levels of theory. It is found that the relative energy of the tautomers is governed by the change in the degree of heterocycle aromaticity upon intramolecular hydrogen transfer. An analysis of geometrical parameters of a hydrogen-bonded system reveals a clear relationship between the aromaticity of the heterocycle, the conjugation in a resonant spacer, and the strengths of the intramolecular hydrogen bonds.