Chemodivergent Synthesis of Polycyclic Aromatic Diarylamines and Carbazoles by Thermal/Photochemical Process-Controlled Dephosphinylative Functionalizations of Amino(phosphinyl)arenes.

A chemodivergent synthesis of polycyclic aromatic diarylamines and carbazoles was established by employing thermally or photochemically controlled processes using KOtBu/1,10-phenanthroline. The synthetic processes involved the dephosphinylation of 9-amino-10-(phosphinyl)phenanthrenes, which were obtained through a regioselective palladium-catalyzed direct [4 + 2] benzannulation of phosphinyl ynamines with 2-iodobiphenyls. When the dephosphinylation was conducted under heating conditions (∼100 °C), it proceeded to yield 9-aminophenanthrene. However, when the reaction was performed under the illumination of purple light (LEDs, λmax = ca. 390 nm), KOtBu/1,10-phenanthroline promoted single-electron-transfer-triggered dephosphinylation followed by cyclization, producing the corresponding π-expanded carbazoles. We successfully synthesized a highly π-expanded dicarbazole through a dual dephosphinylative cyclization. Additionally, we present the optical properties of a series of amino compounds produced through the dephosphinylative processes.

Synthesis, optical properties and crystal structure of (E,E)-1,3-(3,4:9,10-dibenzododeca-1,11-diene-5,7-diyne-1,12-di-yl)benzene.

The de-hydro-benzannulene (E,E)-1,3-(3,4:9,10-dibenzododeca-1,11-diene-5,7-diyne-1,12-di-yl)benzene, C26H16, was successfully synthesized via photocatalyst-assisted stereoselective reductive de-sulfonyl-ation of 1,3-bis-{1-phenyl-sulfonyl-2-[2-(tri-methyl-silylethyn-yl)phen-yl]ethen-yl}benzene, C44H42O4S2Si2, and subsequent desilylative cyclization of the resulting (E,E)-bis-silyl-protected dienyne, C32H34Si2. The structure of the de-hydro-benzannulene thus obtained was confirmed by single-crystal X-ray analysis; three benzene rings are connected to one another by a 1,3-butadiynylene and a pair of ethenylene arrays. Although the π-system expanded efficiently in the de-hydro-benzannulene, it was observed that the butadiynylene and ethenylene arrays were strained, showing smaller [171.3 (2)-172.6 (2) °] and larger bond angles [122.5 (2)-131.9 (2)°] than the conventional bond angles, respectively. In CHCl3, the de-hydro-benzannulene showed the longest absorption band at 377 nm. When irradiated by UV light, it emitted fluorescence at 468 nm (ΦF = 0.26) and 504 nm (ΦF = 0.24) in CHCl3 and in the powdered state, respectively.

Process-Divergent Syntheses of 4- and 5-Sulfur-Functionalized 1,2,3-Triazoles via Copper-Catalyzed Azide-Alkyne Cycloadditions of 1-Phosphinyl-2-sulfanylethynes.

4-Sulfanyl-substituted 1,2,3-triazoles were provided regioselectively with good yields and broad scope via consecutive t-BuOK-promoted dephosphinylation of 1-phosphinyl-2-sulfanylethynes and copper-catalyzed azide-alkyne cycloadditions (CuAAC) with alkyl azides. Unsymmetrically substituted ditriazoles were successfully obtained using a tandem dephosphinylative CuAAC protocol with diazides. Direct CuAAC of the 1-phosphinyl-2-sulfanylethynes with azides afforded regioisomeric mixtures of 4-phosphinyl-5-sulfanyl- and 5-phosphinyl-4-sulfanyl-1,2,3-triazoles that were easily separable from one another. When the phosphinyl- and sulfanyl-substituted triazoles were treated with t-BuOK, the dephosphination proceeded smoothly, yielding the corresponding 5- and 4-sulfanyltriazoles, respectively. 5-(1-Aryl-1-hydroxymethyl)-4-sulfanyltriazoles were synthesized by stepwise treatment of 5-phosphinyl-4-sulfanyltriazole with MeMgBr and arylaldehydes. Additionally, Ph2P(O) and RS groups in the triazoles were easily converted to Ph2P and RSO2 by PhSiH3-reduction and m-CPBA-oxidation, respectively. Following the dephosphinylative CuAAC of 1-phosphinyl-2-(4-t-butylphenylsulfanyl)ethyne with aryl azides and m-CPBA-oxidation, potent antagonists of pregnane X receptor LC-58 and LC-59 were successfully produced.

Zirconium-Based Catalysts in Organic Synthesis.

Zirconium is a silvery-white malleable and ductile metal at room temperature with a crustal abundance of 162 ppm. Its compounds, showing Lewis acidic behavior and high catalytic performance, have been recognized as a relatively cheap, low-toxicity, stable, green, and efficient catalysts for various important organic transformations. Commercially available inorganic zirconium chloride was widely applied as a catalyst to accelerate amination, Michael addition, and oxidation reactions. Well-designed zirconocene perfluorosulfonates can be applied in allylation, acylation, esterification, etc. N-Chelating oganozirconium complexes accelerate polymerization, hydroaminoalkylation, and CO2 fixation efficiently. In this review, the applications of both commercially available and synthesized zirconium catalysts in organic reactions in the last 5 years are highlighted. Firstly, the properties and application of zirconium and its compounds are simply introduced. After presenting the superiority of zirconium compounds, their applications as catalysts to accelerate organic transformations are classified and presented in detail. On the basis of different kinds of zirconium catalysts, organic reactions accelerated by inorganic zirconium catalysts, zirconium catalysts bearing Cp, and organozirconium catalysts without Cp are summarized, and the plausible reaction mechanisms are presented if available.

Pyoderma gangrenosum caused by secukinumab successfully treated with risankizumab: a case report and literature review.

We report a case of pyoderma gangrenosum (PG) caused by secukinumab, which was successfully treated with risankizumab. We also reviewed reported cases of PG caused by interleukin (IL)-17 inhibitors. The clinical course of this case indicates that IL-23 may play an important role in the pathogenesis of PG and therefore IL-23-targeting therapies may be a treatment option for PG.

Dephosphinylative [4 + 2] Benzannulation of Phosphinyl Ynamines: Application to the Modular Synthesis of Polycyclic Aromatic Amines.

A series of 9-amino-10-halophenanthrenes were synthesized through a one-pot process, including dephosphinylative Sonogashira-Hagihara coupling of 2-bromobiphenyls with air-stable phosphinyl ynamines, followed by halonium-promoted [4 + 2] benzannulation of the resulting 2-(aminoethynyl)biphenyls. Nonsubstituted and methyl-substituted 2-bromobiphenyls rapidly underwent the Sonogashira-Hagihara aminoethynylation and the halogenative Friedel-Crafts benzannulation to provide the corresponding amino(halo)phenanthrenes in high yields, while electron-sufficient and -deficient substrates did slowly undergo the former and the latter to result in low yields, respectively. This protocol worked well for the syntheses of highly π-extended aminophenanthrenes and aminobenzonaphthothiophenes with different optical properties. Further application of this approach between 2,2″- and 2',5'-dibromo-p-terphenyls with phosphinyl ynamines led to the regioselective formation of 6,13-diamino-5,12-dihalo- and 5,12-diamino-6,13-dihalo-dibenz[a,h]anthracenes via dual aminoethynylation and [4 + 2] benzannulation. The obtained analogues showed different ultraviolet-visible absorption and photoluminescence spectra with different emission quantum yields in CH2Cl2 solution and the powder state.

Head-to-Tail Oligomerization by Silylene-Tethered Sonogashira Coupling on Ag(111).

On-surface synthesis is a powerful method for the fabrication of π-conjugated nanomaterials. Herein, we demonstrate chemoselective Sonogashira coupling between (trimethylsilyl)ethynyl and chlorophenyl groups in silylethynyl- and chloro-substituted partially fluorinated phenylene ethynylenes (SiCPFPEs) on Ag(111). The desilylative Sonogashira coupling occurred with high chemoselectivity up to 75 %, while the competing Ullmann and desilylative Glaser homocoupling reactions were suppressed. A combination of bond-resolved scanning tunneling microscopy/atomic force microscopy (STM/AFM) and DFT calculations revealed that the oligomers were obtained by the formation of intermolecular silylene tethers (-Me2 Si-) through CH3 -Si bond activation at 130 °C and subsequent elimination of the tethers at an elevated temperature of 200 °C.

Process-Controlled Regiodivergent Copper-Catalyzed Azide-Alkyne Cycloadditions: Tailor-made Syntheses of 4- and 5-Bromotriazoles from Bromo(phosphoryl)ethyne.

We developed a regiodivergent syntheses of 4- and 5-bromo-substituted 1,2,3-triazoles in copper-catalyzed azide-alkyne cycloadditions (CuAACs) by taking advantage of bromo(phosphoryl)ethyne 1 as a bromoethyne equivalent. A one-shot dephosphorylative CuAAC of 1 afforded 4-bromotriazoles, which was transformed into a histone deacetylase 8 (HDAC8)-selective inhibitor, NCC-149. However, the direct CuAAC catalyzed by CuI/Cu(OAc)2 provided 5-bromo-4-phosphoryltriazoles. The consecutive nucleophilic substitution of the bromo group with thiols followed by MeOK-promoted dephosphorylation gave 5-thio-substituted triazoles.

Disproportionation-induced solid-state fluorescence in 6,13-dihydropentacenes.

The thermally and photolytically induced disproportionation of 6,13-dihydropentacene derivatives into tetrahydropentacenes and pentacenes results in unique solid-state fluorescence. The fluorescence thereby depends on the molecular structure and the molecular arrangement in the solid state.

Diacetylene Linked Anthracene Oligomers Synthesized by One-Shot Homocoupling of Trimethylsilyl on Cu(111).

On-surface chemical reaction has become a very powerful technique to conjugate small precursor molecules and several reactions have been proposed with the aim to fabricate functional nanostructures on surfaces. Here we present an unforeseen adsorption mode of 9,10-bis((trimethylsilyl)ethynyl)anthracene on a Cu(111)surface and the resulting one-shot desilylative homocoupling of of the adsorbate by annealing at 400 K. With a combination of high-resolution atomic force microscopy and density functional theory calculations, we found that the triple bonds and silicon atoms of the monomer chemically interact with the copper surface. After the oligomerization, we discovered that the anthracene units are linked to each other via buta-1,3-diynediyl fragments while keeping the surface clean. Furthermore, the force measurement revealed the chemical nature at the center of anthracene unit.

Synthesis of Aryl C-Glycosides via Iron-Catalyzed Cross Coupling of Halosugars: Stereoselective Anomeric Arylation of Glycosyl Radicals.

We have developed a novel diastereoselective iron-catalyzed cross-coupling reaction of various glycosyl halides with aryl metal reagents for the efficient synthesis of aryl C-glycosides, which are of significant pharmaceutical interest due to their biological activities and resistance toward metabolic degradation. A variety of aryl, heteroaryl, and vinyl metal reagents can be cross-coupled with glycosyl halides in high yields in the presence of a well-defined iron complex, composed of iron(II) chloride and a bulky bisphosphine ligand, TMS-SciOPP. The chemoselective nature of the reaction allows the use of synthetically versatile acetyl-protected glycosyl donors and the incorporation of various functional groups on the aryl moieties, producing a diverse array of aryl C-glycosides, including Canagliflozin, an inhibitor of sodium-glucose cotransporter 2 (SGLT2), and a prevailing diabetes drug. The cross-coupling reaction proceeds via generation and stereoselective trapping of glycosyl radical intermediates, representing a rare example of highly stereoselective carbon-carbon bond formation based on iron catalysis. Radical probe experiments using 3,4,6-tri-O-acetyl-2-O-allyl-α-d-glucopyranosyl bromide (8) and 6-bromo-1-hexene (10) confirm the generation and intermediacy of the corresponding glycosyl radicals. Density functional theory (DFT) calculations reveal that the observed anomeric diastereoselectivity is attributable to the relative stability of the conformers of glycosyl radical intermediates. The present cross-coupling reaction demonstrates the potential of iron-catalyzed stereo- and chemoselective carbon-carbon bond formation in the synthesis of bioactive compounds of certain structural complexity.

A biomimetic redox flow battery based on flavin mononucleotide.

The versatility in design of redox flow batteries makes them apt to efficiently store energy in large-scale applications at low cost. The discovery of inexpensive organic electroactive materials for use in aqueous flow battery electrolytes is highly attractive, but is thus far limited. Here we report on a flow battery using an aqueous electrolyte based on the sodium salt of flavin mononucleotide. Flavins are highly versatile electroactive molecules, which catalyse a multitude of redox reactions in biological systems. We use nicotinamide (vitamin B3) as a hydrotropic agent to enhance the water solubility of flavin mononucleotide. A redox flow battery using flavin mononucleotide negative and ferrocyanide positive electrolytes in strong base shows stable cycling performance, with over 99% capacity retention over the course of 100 cycles. We hypothesize that this is enabled due to the oxidized and reduced forms of FMN-Na being stabilized by resonance structures.