Sustainable Access to Acridin-9-(10H)ones with an Embedded m-Terphenyl Moiety Based on a Three-Component Reaction

A Ce(IV)-catalyzed three-component reaction between chalcones, anilines and β-ketoesters followed by a microwave-assisted thermal cyclization afforded 1,3-diaryl-1,2-dihydroacridin-9(10H)-ones. Their microwave irradiation in nitrobenzene, acting both as solvent and oxidant, afforded fully unsaturated 1,3-diarylacridin-9(10H)-ones, which combine acridin-9-(10H)one and m-terphenyl moieties. Overall, the route generates three C-C and one C-N bond and has the advantage of requiring a single chromatographic separation.

Equibiaxially stretchable colorless and transparent polyimides for flexible display substrates

Abstract4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) was reacted with three structurally different diamines to produce poly(amic acid)s, which were then imidized to produce colorless and transparent polyimide (CPI) films through stepwise thermal cyclization. The three amines used to synthesize CPI based on BPADA are: bis(3-aminophenyl)sulfone (APS), p-xylyenediamine (p-XDA), and bis[4-(3-aminophenoxy)-phenyl] sulfone (m-BAPS). The obtained CPI films were almost colorless and exhibited excellent optical transparencies. The solubility of the CPI films in various solvents was investigated, and all the CPI films were found to be soluble in common solvents such as chloroform, dichloromethane, N,N’-dimethyl acetamide, and pyridine. The thermo-optical properties and oxygen transmission rates (O2TRs) of the CPI films were examined for various biaxial stretching ratios in the range of 100–150%, and their properties were compared. When the stretching ratio changed from 100 to 150%, the glass transition temperature and yellow index did not show any significant change; however, the O2TR decreased for all CPI films.

Transition-Metal-Free Synthesis of Pyridine Derivatives by Thermal Cyclization of N-Propargyl Enamines

A transition-metal-free synthesis of pyridine derivatives by 6-endo-dig cyclization of N-propargyl enamines was developed. This method is environmentally friendly and is a high atom economy reaction that is easily accessed to provide pyridine derivatives in moderate to good yield by heating N-propargyl enamines in solvent without additives. The total synthesis of onychine was achieved in 51% yield in only two steps by using this method.

Facile Synthesis, Characterization and in vitro Antibacterial Efficacy of Functionalized 2-Substituted Benzimidazole Motifs

A series of functionalized 2-substituted benzimidazole motifs was designed and successfully synthesized via thermal cyclization of 1,2-diaminobenzene on COOH end of L- leucine to achieve benzimidazole derivatives 6 as the essential precursor. The coupling of the precursor 6 with benzaldehyde derivatives a-h, ketone series i-k, and aryl sulfonyl chlorides l-n led to the formation of the targeted 2-substituted benzimidazole motifs 7a-n in improved yields. The targeted benzimidazole motifs were structurally authenticated through their spectral data and microanalytical parameters. The targeted final moieties were investigated for potential antimicrobial activity using the agar diffusion method with gentamicin as the clinical standard. All the compounds had a broad spectrum of activity with compound 7k having the highest remarkable activity with MIC of 0.98 ± 0.02 µg/mL and MBC value of 3.91 ± 0.10 µg/mL. These findings suggest that compound 7k containing camphor might be a good candidate for the design of new antimicrobial small-molecule drugs.

A general strategy for visible-light decaging based on the quinone cis-alkenyl lock

Combining the fast thermal cyclization of o-coumaric acid derivatives with the intramolecular photoreduction of quinones gives new visible-light photoremovable protecting groups absorbing well above 450 nm.

Direct access to benzo[b]fluorenes via a gold-catalysed A3-coupling strategy

A one-pot combination of gold catalysis and thermal cyclization provides a fast convergent route to benzo[b]fluorenes.