Impact of Side Chain Chemical Structure on Doping and Thermoelectric Properties of Oriented PBTTT Thin Films.

In this contribution, doping of oriented thin films is investigated for three PBTTT polymers bearing different side chains including linear alkyl ─(CH)─H, single ether ─(CH)─O─(CH)─H and alkyl-siloxane ─(CH)─(Si(CH)O)─Si(CH) A combination of transmission electron microscopy, polarized UV-vis-NIR spectroscopy and transport measurements helps uncover the essential role of the chemical nature of side chains on the efficacy of the doping and on the resulting thermoelectric performances in oriented PBTTT films. Siloxane side chains help to reach record alignment level of PBTTT with dichroic ratio beyond 50 for an optimized rubbing temperature but they impede effective doping of PBTTT crystals with FTCNNQ, resulting in very poor TE properties. By contrast, doping the amorphous phase of all three PBTTTs with magic blue (MB) results in excellent TE performances.

Regioselective Copper(I)-Catalyzed Direct C(3)-H (Hetero)arylation of 6-(Hetero)arylated 1,2,4-Triazolo[4,3-]pyridazines: Ligand-Free Approach.

The first efficient Cu(I) catalyzed regioselective C3-(hetero)arylation of 6-(hetero)arylated 1,2,4-triazolo[4,3-]pyridazines has been developed to streamline the synthesis of pharmaceutically important 3,6-diarylated 1,2,4-triazolo[4,3-]pyridazines. This direct (hetero)arylation is compatible with a range of aryl iodides and tolerates a variety of functional groups (23 examples). A series of new 3,6-diarylated 1,2,4-triazolo[4,3-]pyridazines were synthesized with good to excellent yields (up to 98%).

Controlling conjugated polymer morphology by precise oxygen position in single-ether side chains.

Recently, polar side chains have emerged as a functional tool to enhance conjugated polymer doping properties by improving the polymer miscibility with polar chemical dopants and facilitate solvated ion uptake. In this work, we design and investigate a novel family of side chains containing a single ether function, enabling the modulation of the oxygen atom position along the side chain. A meticulous investigation of this new polymer series by differential scanning calorimetry, fast scanning chip calorimetry and X-ray scattering shows that polymers bearing single-ether side chains can show high degree of crystallinity under proper conditions.

Synthesis of Trifluoromethylated Pyrimido[1,2-]indazole Derivatives through the Cyclocondensation of 3-Aminoindazoles with Ketoester and Their Functionalization via Suzuki-Miyaura Cross-Coupling and SN Reactions.

A new series of trifluoromethylated pyrimido[1,2-]indazol-4(1)-one derivatives was synthesized with good to excellent yields through a simple condensation of 3-aminoindazole derivatives with ethyl 4,4,4-trifluoro 3-oxobutanoate. The functionalization of the corresponding chlorinated fused tricyclic scaffolds via Suzuki-Miyaura and aromatic nucleophilic substitution reactions led to the synthesis of highly diverse trifluoromethylated pyrimido[1,2-]indazole derivatives with good yields.

Three Component One-Pot Synthesis and Antiproliferative Activity of New [1,2,4]Triazolo[4,3-]pyrimidines.

A series of new [1,2,4]triazolo[4,3-a]pyrimidine derivatives was prepared using a one-pot three-component synthesis from 5-amino-1-phenyl-1-1,2,4-triazoles, aromatic aldehydes and ethyl acetoacetate. The compound structures were confirmed by IR, H-NMR, C-NMR, HRMS and X-ray analyses. The biological activity of these compounds as antitumor agents was evaluated.

Efficient Synthesis of 1-Benzo[4,5]imidazo[1,2-][1,3]oxazin-1-one Derivatives Using AgCO/TFA-Catalyzed 6- Cyclization: Reaction Scope and Mechanistic Study.

A small library of 1-benzo[4,5]imidazo[1,2-][1,3]oxazin-1-one derivatives was prepared in good to excellent yields, involving a AgCO/TFA-catalyzed intramolecular oxacyclization of -2-alkynylbenzimidazole substrates. In all experiments, the 6-- cyclization was exclusively achieved since the possible heterocycle was not observed, indicating the high regioselectivity of this process. The scope and limitations of the silver catalyzed cyclization of --2-alkynylbenzimidazoles as substrates, bearing various substituents, were investigated.

Stepwise synthesis of 2,6-difunctionalized ethyl pyrazolo[1,5-]pyrimidine-3-carboxylate site-selective cross-coupling reactions: experimental and computational studies.

A variety of novel disubstituted 2-(alknyl, aryl and arylamine)-6-alkynylpyrazolo[1,5-]pyrimidine derivatives was prepared sequential site-selective cross-coupling reactions from 2,6-dibromopyrazolo[1,5-]pyrimidine 3. The regio-controlled Sonogashira-type coupling of 3 with a wide range of terminal alkynes proceeded smoothly with excellent selectivity in favor of the C6-position through careful adjustment of the coupling conditions, followed by the subsequent introduction of alkynyl, aryl or arylamine groups at the C2-position the Sonogashira, Suzuki-Miyaura and Buchwald-Hartwig coupling reactions, respectively. These promising results allow for further use and diversification of the chemically and biologically interesting pyrazolo[1,5-]pyrimidine scaffold.

Simple and Expedient Access to Novel Fluorinated Thiazolo- and Oxazolo[3,2-]pyrimidin-7-one Derivatives and Their Functionalization via Palladium-Catalyzed Reactions.

An efficient, versatile, and one-pot method for the preparation of novel fluorinated thiazolo- and oxazolo[3,2-]pyrimidin-7-ones is described from 2-aminothiazoles or 2-amino-oxazoles and fluorinated alkynoates. This transformation, performed under transition-metal-free conditions, offers new fluorinated cyclized products with good to excellent yields. Moreover, the functionalization of these -fused scaffolds via the Suzuki-Miyaura and Sonogashira cross-coupling reactions led to the synthesis of highly diverse thiazolo- and oxazolo[3,2-]pyrimidin-7-ones.

A AgCO/TFA-catalyzed intramolecular annulation approach to imidazo[1,2-][1,3]oxazin-5-one derivatives.

A series of 2,7-disubstituted 3-methylimidazo[1,2-][1,3]oxazin-5-ones were synthesized in good yields AgCO/TFA-mediated intramolecular annulation of -Boc-2-alkynyl-4-bromo(alkynyl)-5-methylimidazoles. This methodology was carried out in the presence of a catalytic amount of silver carbonate and trifluoroacetic acid in dichloroethane at 60 °C. In all experiments, only the six-membered ring product was obtained since the possible five-membered compound was not observed, proving the high regioselectivity of this approach.

Efficient microwave-assisted Suzuki-Miyaura cross-coupling reaction of 3-bromo pyrazolo[1,5-]pyrimidin-5(4)-one: towards a new access to 3,5-diarylated 7-(trifluoromethyl)pyrazolo[1,5-]pyrimidine derivatives.

A convenient and efficient synthetic route to C3-arylated 7-trifluoromethylpyrazolo[1,5-]pyrimidin-5-one derivatives has been reported starting from 3-bromo-7-(trifluoromethyl)pyrazolo[1,5-]pyrimidin-5-one through a Suzuki-Miyaura cross-coupling reaction. The arylation (heteroarylation) strategy can be performed using a wide variety of aryl and heteroaryl boronic acids and requiring a tandem catalyst XPhosPdG2/XPhos to avoid the debromination reaction. These optimized conditions were successfully extended to the synthesis of 7-, 8- and 9-arylated pyrimido[1,2-]indazol-2-ones from their corresponding brominated starting materials.

A Direct and an Efficient Regioselective Synthesis of 1,2-Benzothiazine 1,1-dioxides, β-Carbolinones, Indolo[2,3-]pyran-1-ones, Indolo[3,2-]pyran-1-ones, Thieno[2,3-]pyran-7-ones and Pyrano[3',4':4,5]imidazo[1,2-]pyridin-1-ones via Tandem Stille/Heterocyclization Reaction.

A general regioselective one-pot synthesis of 1,2-benzothiazine 1,1-dioxides from 2-iodo benzenesulfonamide moieties and allenylstannanes is described using a domino Stille-like/Azacyclization reaction. The conditions developed also opened a novel access to β-carbolinones, indolopyranones, thienopyranones and pyrano-imidazopyridines.

Pyrimido[1,2-b]indazole derivatives: Selective inhibitors of human monoamine oxidase B with neuroprotective activity.

Structurally diverse heterotricyclic compounds are recognized as monoamine oxidase (MAO) inhibitors and thus represent an appealing scaffold in development and optimization of novel MAO inhibitors. Herein we explored the chemical space of pyrimido[1,2-b]indazoles as MAO inhibitors by preparing a small library of (hetero)aryl derivatives. An efficient synthetic strategy was developed starting from commercially available 1H-indazol-3-amines, which were converted to various 3-bromoheterotricyclic derivatives and further functionalized via Suzuki-Miyaura coupling reaction.

Efficient Access to 3,5-Disubstituted 7-(Trifluoromethyl)pyrazolo[1,5-]pyrimidines Involving SAr and Suzuki Cross-Coupling Reactions.

An efficient and original synthesis of various 3,5-disubstituted 7-(trifluoromethyl)pyrazolo[1,5-]pyrimidines is reported. A library of compounds diversely substituted in C-3 and C-5 positions was easily prepared from a common starting material, 3-bromo-7-(trifluoromethyl)pyrazolo[1,5-]pyrimidin-5-one. In C-5 position, a SAr type reaction was achieved by first activating the C-O bond of the lactam function with PyBroP (Bromotripyrrolidinophosphonium hexafluorophosphate), followed by the addition of amine or thiol giving monosubstituted derivatives, whereas in C-3 position, arylation was performed via Suzuki-Miyaura cross-coupling using the commercially available aromatic and heteroaromatic boronic acids.

Synthetic Modification of 9α- and 9β-Hydroxyparthenolide by Heck or Acylation Reactions and Evaluation of Cytotoxic Activities.

Motivated by the widely reported anticancer activity of parthenolides and their derivatives, a series of new substituted parthenolides was efficiently synthesized. Structural modifications were performed at the C-9 and C-13 positions of 9- and 9-hydroxyparthenolide, which were isolated from the aerial parts of . Twenty-one derivatives were synthesized and evaluated for their cytotoxic activity against HS-683, SK-MEL-28, A549, and MCF-7 human cancer cell lines using the MTT colorimetric assay.