The allylnickel-catalyzed living coordination polymerization of allene derivatives was carried out in protic solvents such as EtOH to figure out their effect on the polymerization behavior. For example, the coordination polymerization of methoxyallene (2a) by [(allyl)NiOCOCF3]2 (1)/PPh3 in EtOH proved to proceed in a living fashion giving a narrowly dispersed polymer in a high yield. In this case, a remarkable acceleration of the polymerization and the higher selectivity of the 1,2-polymerization were observed compared to the case of the polymerization in aprotic solvents such as toluene. That is, the polymerization of 2a (50 equiv, [2a]0 = 1.0 M) was complete within 2 h in EtOH to give a polymer in 95% yield (M n = 4400, M w/M n = 1.10, 1,2-:2,3-polymerizations = 63:37), while it required 12 h in toluene to obtain a polymer having higher content of the 2,3-polymerized unit in a 99% yield (M n = 4100, M w/M n = 1.07, 1,2-:2,3-polymerizations = 27:73). In protic solvents, the actual propagating species was supposed to be a cationic π-allylnickel complex on the basis of its 1H NMR and 19F NMR spectra. The use of protic sources such as pyrrole, indole, and phenol was also found to be effective to accelerate the polymerization and to increase the 1,2-polymerization selectivity.

No abstract

As a part of our efforts to develop potential imaging agents for ascorbate bioactivity, 5-O-(4-[125 I] iodobenzyl)-L-ascorbic acid ([ 125 I]1) was prepared through a two-step sequence which involved radioiododestannylation of a protected tributylstannyl precursor 6, followed by hydrolysis in acidic methanol of the protecting groups in 61% overall radiochemical yield, with a radiochemical purity of over 98% and a specific activity of more than 15.4 GBq/μmol. Tissue distribution of [ 125 I]1 in tumor-bearing mice showed signs of distribution profiles similar to the reported results for 6-deoxy-6-[18 F]fluoro-L-ascorbic (6-18 FAsA) acid and 6-deoxy-6-[131 I]iodo-L-ascorbic acid (6-131 IAsA) but with notable differences in the adrenal glands, in which considerably lower uptake of radioactivity and rapid clearance with time were observed. Pretreatment of mice with a known inhibitor of ascorbate transport, sulfinpyrazone, did not produce any significant change in the adrenal uptake of radioactivity after injection of [ 125 I]1 compared to the control, suggesting that uptake in the adrenal glands is independent of the sodium-dependent vitamin C transporter 2 transport mechanism. Introduction of a bulky substituent at C-5 on AsA, such as an iodobenzyloxy group, may not be suitable for the design of analogs that may still be able to maintain characteristic distribution properties in vivo seen with AsA itself.

No abstract

We herein report a case of hepatitis C virus (HCV)-associated cryoglobulinemic livedo reticularis in a woman in her 60s that improved with direct-acting antivirals (DAAs). Hyperpigmentation was observed in both lower legs, and a skin biopsy confirmed livedo reticularis, suggesting a relationship with cryoglobulinemia and HCV infection. DAAs with an NS5A inhibitor+NS3/4A protease inhibitor (glecaprevir/pibrentasvir) were administered for eight weeks, and a sustained virological response (SVR) was obtained. The disappearance of serum cryoglobulin was confirmed approximately two years after an SVR was obtained and livedo reticularis was improved. DAA therapy can be an effective therapeutic option for extrahepatic complications associated with HCV infection.