Ishigadine A,a new canthin-6-one alkaloid from an Okinawan marine sponge Hyrtios sp.

A new indole alkaloid with the canthin-6-one skeleton, ishigadine A, has been isolated from an Okinawan marine sponge Hyrtios sp. The structure of ishigadine A was elucidated on the basis of spectroscopic analyses. Ishigadine A is a new canthin-6-one alkaloid possessing a hydroxy group, a 1,3-dimethyl-4-methylthioimidazolium, and a 1-propylguanidine. Ishigadine A is the third canthin-6-one alkaloid from sponges. Ishigadine A might be generated from l-arginine, l-histidine, and l-tryptophan. Ishigadine A exhibited moderate cytotoxicity against L1210 murine leukemia cells.     

Synthesis and properties of hyperbranched poly(ether sulfone)s prepared by self‐polycondensation of novel AB2 monomer

Hyperbranched poly(ether sulfone)s were prepared by the self‐polycondensation of the novel AB₂ monomer, 4‐(3,5‐hydroxyphenoxy)‐4′‐fluorodiphenylsulfone. The high‐molecular‐weight polymers were isolated in good yields. The degree of branching (DB) of the resulting polymers was investigated by the preparation of dendritic and linear model compounds. The DB determined by gated decoupling ¹³C NMR measurements was in the range 0.17–0.41 and was dependent on the base used for the self‐polycondensation. It was found that cesium fluoride was an effective base to form the polymer having the DB of 0.41. The resulting hyperbranched poly(ether sulfone)s showed good solubility in organic solvents. The solubility and the glass transition temperature of the polymers were influenced by the terminal functional groups. The unique thermal crosslinking phenomenon was observed during the DSC measurements of the hydroxyl‐terminated hyperbranched poly(ether sulfone) under air condition. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Control of thermoresponsivity of biocompatible poly(trimethylene carbonate) with direct introduction of oligo(ethylene glycol) under various circumstances

Poly(trimethylene carbonate) (PTMC) is a well‐known biodegradable polymer with good biocompatible properties which make it suitable for biomedical applications. Poly(5‐[2‐{2‐(2‐methoxyethoxy)ethyoxy}‐ethoxymethyl]‐5‐methyl‐1,3‐dioxa‐2‐one) (PTMC‐MOE3OM) and copolymers, bearing oligo ethylene glycol (OEG) at the side chain of PTMC backbone, were selected to investigate the cloud point behavior by solvents such as PBS, water, 10% ethanol solution and various ionic strengths. A pH‐responsive copolymer, poly(TMCM‐MOE3OM‐co‐(5‐methyl‐5‐carboxylic‐1,3‐dioxane‐2‐one)) as carboxylic acid carbonate showed a decreased critical temperature at pH 2. Photo‐responsive copolymer, poly(TMCM‐MOE3OM‐co‐coumarin derivatives) bearing 1% and 10% of photo‐induced molecules (7‐[(5‐(5‐methyl‐1,3‐dioxa‐2‐one)methoxy)]‐methoxy coumarin (TMCM‐coumarin)) exhibited a low cloud point because of the hydrophobic moieties. Meanwhile, alternative coumarin polymer including 2% of 4‐methyl‐7‐[(5‐(5‐methyl‐1,3‐dioxa‐2‐one)methoxy)butoxy)]‐methoxy coumarin (TMCM‐4‐methyl‐coumarin) has been successfully synthesized and copolymerized as a novel molecule. The various combinations of monomers were studied and the significant properties were determined via external triggers after copolymerization. This study showed basically synthetic progress toward designs and trivial rationalization of thermoresponsive copolymers close to body temperature. At present, various pendant groups as side part affect to the lower critical solution temperature (LCST) and biodegradable polymer in order to utilize the actual external stimuli application. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3466–3474     

RAFT synthesis of an amphiphilic block copolymer bearing chlorin rings in the hydrophobic segment and its application in photodynamic therapy

RAFT polymerization of styrene (St) in the presence of 5,10,15,20‐tetrakis(pentafluorophenyl)porphyrin (TFPP) was conducted using 4‐cyano‐4‐(thiobenzoyl)thiopentanoic acid as a chain‐transfer agent and azobisisobutyronitrile as an initiator at 60 °C. The resulting polymer exhibited a chlorin‐like UV‐vis spectrum, which indicated that the polymer possessed a reduced TFPP structure. Furthermore, an SEC trace recorded using UV‐vis detector (λ = 410 nm), which selectively detected the TFPP‐incorporated polymer, shifted toward higher molecular mass as the polymerization progressed. This evidence indicated that TFPP acted as a vinylene‐type monomer, such as maleimide, to form a copolymer, namely, poly(St‐co‐TFPP). The mole fraction of TFPP units was estimated to be 0.74 × 10^?3, which was close to that in the feed (1 × 10^?3). Chain extension of poly(St‐co‐TFPP) with polyethylene glycol monomethyl ether acrylate (PEGA) was performed to afford the amphiphilic block copolymer poly(St‐co‐TFPP)‐b‐poly(PEGA). The degrees of polymerization of St and PEGA were determined to be 64 and 75, respectively. Poly(St‐co‐TFPP)‐b‐poly(PEGA) formed micelles following dialysis. The median diameter of the micelles in solution was determined to be 16 nm by DLS. The photocytotoxicity of the micelle solution was evaluated in a human glioblastoma cell line (U251) and an N‐methyl‐N'‐nitro‐N‐nitrosoguanidine‐induced mutant of a rat murine RGM‐1 gastric carcinoma mucosal cell line (RGK‐1). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3395–3403     

5,11-Diazadibenzo[hi,qr]tetracene: Synthesis,Properties, and Reactivity toward Nucleophilic Reagents

5,11-Diazadibenzo[hi,qr]tetracene was synthesized as a new nitrogen-substituted polycyclic heteroaromatic compound by Pd-catalyzed cycloisomerization of an alkyne precursor followed by oxidative cyclization with bis(trifluoroacetoxy)iodobenzene. The substitution of imine-type nitrogen atoms significantly enhanced its electron-accepting character and facilitated the direct nucleophilic addition of arylamines under strongly basic conditions to afford the desired amino-substituted products. The introduction of amino groups induced a remarkable red-shift in their absorption spectra; the tetrasubstituted product exhibited intense near-infrared absorbing property. Furthermore, the π-electronic system, which includes a redox-active 1,4-diazabutadiene moiety, underwent reversible interconversion to its corresponding reduced form upon reduction with NaBH₄ and aerobic oxidation.     

Synthesis of Benzopyran-4-Amides Potassium Channel Openers Via Palladium-Catalyzed Amidation

The novel potassium channel openers benzopyran-4-amides have been synthesized via palladium-catalyzed amidation of 4-bromobenzopyrans under an atmoshere in the presence of an equivalent of potassium iodide.