10.1002/cssc.201000112
Lignin, a complex polymer in biomass, is difficult to degrade efficiently and is often burned rather than utilized for chemical production. The study focuses on cleaving the ?-O-4 bonds, which are dominant in lignin, using guaiacylglycerol-?-guaiacyl ether (GG) and veratrylglycerol-?-guaiacyl ether (VG) as model compounds. The research found that in 1-H-3-methylimidazolium chloride ([HMIM]Cl), both GG and VG underwent catalytic hydrolysis to produce guaiacol with over 70% yield at 150°C. The ionic liquid could be reused without significant loss of activity. The study also explored the effects of substrate concentration, water concentration, and recycling of the ionic liquid, showing that higher water concentration slightly increased bond cleavage efficiency. The proposed mechanism involves acid-catalyzed dehydration and coupling reactions, followed by hydrolysis of intermediate products. This method demonstrates potential for efficient lignin degradation and could be applicable to real lignin or lignocelluloses, offering a sustainable alternative for biomass utilization.
10.1055/s-0031-1290658
The research focuses on the asymmetric total synthesis of (–)-dehydrodiconiferyl alcohol (1), a biologically active neolignan with potential antioxidant, antitumor, and other pharmacological properties. The synthesis involves a rhodium-catalyzed intramolecular C–H insertion reaction, which is key for achieving the trans-disubstituted dihydrobenzofuran ring with high diastereoselectivity. The process starts from commercially available guaiacol and includes 13 steps, utilizing various reactants such as aryl bromide 4, ortho-arylmethyloxy aryldiazoacetates, and chiral auxiliaries derived from mandelic acid. The experiments involve several reactions, including condensation, diazotransfer, C–H insertion, Heck reaction, and reductive manipulations. Analytical techniques used to characterize the synthesized compound include optical rotation, infrared spectroscopy (IR), nuclear magnetic resonance (NMR), and high-resolution mass spectrometry (HRMS), ensuring that the final product is spectroscopically identical to a natural sample of (–)-dehydrodiconiferyl alcohol.
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