2555-98-8Relevant articles and documents
NMR Assignment for Diaryl Ether Structures (4-O-5 Structures) in Pine Wood Lignin
Li, Yanding,Akiyama, Takuya,Yokoyama, Tomoya,Matsumoto, Yuji
, p. 1921 - 1929 (2016/07/06)
A 4-O-5-tetramer lignin model compound carrying β-O-4 linkages on each of the side-chain moieties was synthesized, as well as 4-O-5-coupled dehydrodiconiferyl alcohol. By comparison with their NMR data, two cross-signals in the HSQC spectrum of pine milled wood lignin recorded in DMSO-d6 were assigned to H2/C2 and H6/C6 correlations on the aromatic rings of 4-O-5-linked units. Although the H2/C2 correlation peak appeared in the same region as syringyl units, nitrobenzene oxidation of the pine lignin did not yield any syringyl-type product, but did release a 4-O-5-type product.
Identification and Synthesis of New Ferulic Acid Dehydrodimers Present in Grass Cell Walls
Ralph, John,Quideau, Stephane,Grabber, John H.,Haffield, Ronald D.
, p. 3485 - 3498 (2007/10/02)
Seven isomeric dehydrodimers of ferulic acid (4-hydroxy-3-methoxycinnamic acid) have been synthesized and identified in extracts of saponified cell walls of cocksfoot, switchgrass, and suspension-cultured corn.Dehydrodimers (E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid, trans-5--2-(4-hydroxy-3-methoxyphenyl)-7-methoxy-2,3-dihydrobenzofuran-3-carboxylic acid, (Z)-β--2-methoxyphenoxy>-4-hydroxy-3-methoxycinnamic acid, (E)-3--2-methoxyphenoxy>-4-hydroxy-5-methoxycinnamic acid, (E,E)-4,4'-dihydroxy-3,5'-dimethoxy-β,3'-bicinnamic acid, 4,4'-dihydroxy-3,3'-dimethoxy-β,β'-bicinnamic acid, and trans-7-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-6-methoxy-1,2-dihydronaphthalene-2,3-dicarboxylic acid, all arise from oxidative coupling of ferulate esters in cell walls and represent products of 8-5, 8-8, 8-O-4, 4-O-5, and 5-5 radical coupling.Prior literature has acknowledged only the presence of the 5-5 coupled dehydrodimer (E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid.Consequently, by measuring only a single dehydrodimer and assuming inappropriate response factors, ferulate dehydrodimers have been underestimated by factors of up to 20.Synthetic routes to all seven isomers have been developed to provide structural authentication and determination of GC response factors.