Deprotection of durable benzenesulfonyl protection for phenols — efficient synthesis of polyphenols

<p>A robust protection method for phenol was demonstrated by the use of durable benzenesulfonyl group, which survives various harsh reaction conditions using Grignard reagent, organolithium reagent, metal alkoxide, phosgene, mineral, and Lewis acids. A facile deprotection condition utilizing pulverized KOH (5 equiv) and <i>t</i>-BuOH (10 equiv) in hot toluene makes this protocol as a practical method, which can be applied to the multistep synthesis of biologically and medicinally important polyphenol compounds.</p

One-Pot Conversion of Carbohydrates into Pyrrole-2-carbaldehydes as Sustainable Platform Chemicals

A practical conversion method of carbohydrates into <i>N</i>-substituted 5-(hydroxymethyl)­pyrrole-2-carbaldehydes (pyrralines) was developed by the reaction with primary amines and oxalic acid in DMSO at 90 °C. Further cyclization of the highly functionalized pyrralines afforded the pyrrole-fused poly-heterocyclic compounds as potential intermediates for drugs, food flavors, and functional materials. The mild Maillard variant of carbohydrates and amino esters in heated DMSO with oxalic acid expeditiously produced the pyrrole-2-carbaldehyde skeleton, which can be concisely transformed into the pyrrole alkaloid natural products, 2-benzyl- and 2-methylpyrrolo­[1,4]­oxazin-3-ones <b>8</b> and <b>9</b>, lobechine <b>10</b>, and (−)-hanishin <b>11</b> in 23–32% overall yields from each carbohydrate

Role of Ring <i>Ortho</i> Substituents on the Configuration of Carotenoid Polyene Chains

The 9-(<i>Z</i>)-configuration was exclusively obtained in the carotenoid polyene chain irrespective of olefination and disconnection methods for terminal <i>ortho</i>-unsubstituted benzene rings. The 2,6-dimethyl substituents in the terminal rings secure an all-(<i>E</i>)-polyene structure. The single molecular conductance of the pure 9-(<i>Z</i>)-carotene was measured for the first time to be 1.53 × 10^–4 ± 6.37 × 10^–5G₀, whose value was 47% that of the all-(<i>E</i>)-carotene ((3.23 × 10^–4) ± (1.23 × 10^–4) G₀)

Aerosol Cross-Linked Crown Ether Diols Melded with Poly(vinyl alcohol) as Specialized Microfibrous Li⁺ Adsorbents

Crown ether (CE)-based Li⁺ adsorbent microfibers (MFs) were successfully fabricated through a combined use of CE diols, electrospinning, and aerosol cross-linking. The 14- to 16-membered CEs, with varied ring subunits and cavity dimensions, have two hydroxyl groups for covalent attachments to poly­(vinyl alcohol) (PVA) as the chosen matrix. The CE diols were blended with PVA and transformed into microfibers via electrospinning, a highly effective technique in minimizing CE loss during MF fabrication. Subsequent aerosol glutaraldehyde (GA) cross-linking of the electrospun CE/PVA MFs stabilized the adsorbents in water. The aerosol technique is highly effective in cross-linking the MFs at short time (5 h) with minimal volume requirement of GA solution (2.4 mL g^–1 MF). GA cross-linking alleviated CE leakage from the fibers as the CEs were securely attached with PVA through covalent CE–GA–PVA linkages. Three types of CE/PVA MFs were fabricated and characterized through Fourier transform infrared-attenuated total reflection, ¹³C cross-polarization magic angle spinning NMR, field emission scanning electron microscope, N₂ adsorption/desorption, and universal testing machine. The MFs exhibited pseudo-second-order rate and Langmuir-type Li⁺ adsorption. At their saturated states, the MFs were able to use 90–99% CEs for 1:1 Li⁺ complexation, suggesting favorability of their microfibrous structures for CE accessibility to Li⁺. The MFs were highly Li⁺-selective in seawater. Neopentyl-bearing CE was most effective in blocking larger monovalents Na⁺ and K⁺, whereas the dibenzo CE was best in discriminating divalents Mg²⁺ and Ca²⁺. Experimental selectivity trends concur with the reaction enthalpies from density functional theory calculations, confirming the influence of CE structures and cavity dimensions in their “size-match” Li⁺ selectivity

Table_1_Lycorine Displays Potent Antitumor Efficacy in Colon Carcinoma by Targeting STAT3.DOCX

<p>Signal transducer and activator of transcription 3 (STAT3) is an attractive therapeutic target for cancer treatment. In this study, we identify lycorine is an effective inhibitor of STAT3, leading to repression of multiple oncogenic processes in colon carcinoma. Lycorine selectively inactivates phospho-STAT3 (Tyr-705), and subsequent molecular docking uncovers that lycorine directly binds to the SH2 domain of STAT3. Consequently, we find that lycorine exhibits anti-proliferative activity and induces cell apoptosis on human colorectal cancer (CRC) in vitro. Lycorine induces the activation of the caspase-dependent mitochondrial apoptotic pathway, as indicated by activation of caspase and increase of the ratio of Bax/Bcl-2 and mitochondrial depolarization. Overexpressing STAT3 greatly blocks these effects by lycorine in CRC cells. Finally, lycorine exhibits a potential therapeutic effect in xenograft colorectal tumors by targeting STAT3 without observed toxicity. Taken together, the present study indicates that lycorine acts as a promising inhibitor of STAT3, which blocks tumorigenesis in colon carcinoma.</p