1835-11-6Relevant articles and documents
Synthesis of β-O-4-type artificial lignin polymers and their analysis by NMR spectroscopy
Kishimoto, Takao,Uraki, Yasumitsu,Ubukata, Makoto
, p. 2982 - 2987 (2008)
We describe the synthesis and NMR spectroscopic analysis of three artificial lignin polymers containing only the β-O-4 substructure: syringyl-type homopolymer, p-hydroxyphenyl-type homopolymer and guaiacyl/syringyl-type heteropolymer. Using gel permeation chromatography, the weight-average degree of polymerization (DPw) of the three polymers was determined as 19.2, 38.6, and 13.9, respectively. The polymers were prepared based on the synthetic methodology of guaiacyl-type homopolymer, and were fully characterized using 1H-, 13C-, and 1H- 13C NMR spectroscopy of the acetylated and non-acetylated forms. The spectra of guaiacyl/syringyl-type heteropolymers were in good agreement with those of the β-O-4 substructure of milled wood lignin obtained from the hardwood of Japanese white birch. The Royal Society of Chemistry.
Ipomoeassin F Binds Sec61α to Inhibit Protein Translocation
Zong, Guanghui,Hu, Zhijian,O'Keefe, Sarah,Tranter, Dale,Iannotti, Michael J.,Baron, Ludivine,Hall, Belinda,Corfield, Katherine,Paatero, Anja O.,Henderson, Mark J.,Roboti, Peristera,Zhou, Jianhong,Sun, Xianwei,Govindarajan, Mugunthan,Rohde, Jason M.,Blanchard, Nicolas,Simmonds, Rachel,Inglese, James,Du, Yuchun,Demangel, Caroline,High, Stephen,Paavilainen, Ville O.,Shi, Wei Q.
, p. 8450 - 8461 (2019)
Ipomoeassin F is a potent natural cytotoxin that inhibits growth of many tumor cell lines with single-digit nanomolar potency. However, its biological and pharmacological properties have remained largely unexplored. Building upon our earlier achievements
Chromium-Salen Complex/Nitroxyl Radical Cooperative Catalysis: A Combination for Aerobic Intramolecular Dearomative Coupling of Phenols
Nagasawa, Shota,Fujiki, Shogo,Sasano, Yusuke,Iwabuchi, Yoshiharu
, p. 6952 - 6968 (2021/05/29)
We describe an aerobic intramolecular dearomative coupling reaction of tethered phenols using a catalytic system consisting of a chromium-salen (Cr-salen) complex combined with a nitroxyl radical. This novel catalytic system enables formation of various spirocyclic dienone products including those unable to be accessed by previously reported methods efficiently under mild reaction conditions.
Thio-assisted reductive electrolytic cleavage of lignin β-O-4 models and authentic lignin
Fang, Zhen,Flynn, Michael G.,Jackson, James E.,Hegg, Eric L.
, p. 412 - 421 (2021/01/28)
Avoiding the use of expensive catalysts and harsh conditions such as elevated temperatures and high pressures is a critical goal in lignin depolymerization and valorization. In this study, we present a thio-assisted electrocatalytic reductive approach using inexpensive reticulated vitreous carbon (RVC) as the working cathode to cleave the β-O-4-type linkages in keto aryl ethers. In the presence of a pre-electrolyzed disulfide (2,2′-dithiodiethanol) and a radical inhibitor (BHT) at room temperature at a current density of 2.5 mA cm-2, cathodic reduction of nonphenolic β-O-4 dimers afforded over 90% of the corresponding monomeric C-O cleavage products in only 1.5 h. Extended to DDQ-oxidized poplar lignin, this combination of electric current and disulfide, applied over 6 h, released 36 wt% of ethyl acetate soluble fragments and 26 wt% of aqueous soluble fragments, leaving only 38 wt% of insoluble residue. These findings represent a significant improvement over the current alone values (24 wt% ethyl acetate soluble; 22 wt% aqueous soluble; 54 wt% insoluble residue) and represent an important next step in our efforts to develop a mild electrochemical method for reductive lignin deconstruction.
