Oxidative Coupling of Phenols and the Biosynthesis of Lignin

Brunow, Carl Gustav Alexander; Kilpeläinen, Ilkka; Sipilä, Antti Jussi; Syrjänen, Karí; Karhunen, Pirkko Paula Tellervo; Setälä, Harri; Rummakko, Petteri

doi:10.1021/bk-1998-0697.ch010

Cited by 81 publications

(68 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since no water addition to the quinone methide is observed, it is conceivable that the addition of the coniferyl alcohol oligomers is favoured over the water molecule by the micellar lipophilic environment from which water is excluded. Moreover, as already pointed out by Brunow and co-workers, [4] our working (almost neutral) pH favours the formation of benzyl aryl ethers over the benzylic alcohols, as products of the phenolic addition to the quinone methide.…”

Section: Wwwchemeurjorgsupporting

confidence: 71%

“…Addition reaction of the other phenolic oligomers that are created in the reaction mixture on this conjugated olefin allows the production of new oligomers with a higher degree of polymerisation, according to a regularly defined chain-reaction module. A formal, strictly alternate sequence of a radical and an ionic step underlines the reaction progress, thus generating ordered oligolignol structures formed by coniferyl alcohol subunits (according to the generally accepted practice of using coniferyl alcohol as the only starting material for the in vitro experiments [4] ). This consideration marks an important difference with what is generally reported in the current literature, for which lignin formation is known to proceed in a random fashion by radical and ionic steps.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Lignin Chemistry: Biosynthetic Study and Structural Characterisation of Coniferyl Alcohol Oligomers Formed In Vitro in a Micellar Environment

Reale¹,

Attanasio²,

Spreti³

et al. 2010

Chemistry A European J

View full text Add to dashboard Cite

Model coniferyl alcohol lignin (the so-called dehydrogenative polymerisate, DHP) was produced in water under homogeneous conditions guaranteed by the presence of a micellised cationic surfactant. A complete study of the activity of the enzymatic system peroxidase/H(2)O(2) under our reaction conditions was reported and all the reaction products up to the pentamer were characterised by (1)H NMR spectroscopy and ESI mass spectrometry. Our system, and the molecules that have been generated in it, represent a closer mimicry of the natural microenvironment since an enzyme, under micellar conditions, reproduces the cell system better than in buffer alone. On the basis of the oligomers structures a new biosynthetic perspective was proposed that focused attention on a coniferyl alcohol dimeric quinone methide as the key intermediate of the reaction. A formal, strictly alternate sequence of a radical and an ionic step underlines the reaction, thus generating ordered oligolignols structures. Alternatively to other model lignins, our olignols present a lower degree of radical coupling between oligomeric units. This offers a closer biosynthetic situation to the observation of a low rate of radical generation in the cell wall.

show abstract

Section: Wwwchemeurjorgsupporting

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Lignin Chemistry: Biosynthetic Study and Structural Characterisation of Coniferyl Alcohol Oligomers Formed In Vitro in a Micellar Environment

Reale¹,

Attanasio²,

Spreti³

et al. 2010

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…However, based on our NMR results, the DB substructure is also present in the lignin of ML of native SM. The absence of DB and SD correlations from HSQC of MWL pur of hot-water ESM (ESM_DCM; note that HWE is performed in mild acid conditions) may serve as an additional evidence of cleavage of these structures in mild acid conditions [22,24]. The cleavage of SD substructure during HWE supports the presence of β-1 substructure in MWL of ESM_DCM whose C β -H β correlation is indicated in the HSQC (Figure 4b, E β ) [24].…”

Section: Resultsmentioning

confidence: 66%

“…The results of determination of the PhOH group content of MWL pur s indicate an increase of the PhOH groups during HWE and corroborate previous results [5,7] suggesting the cleavage of aryl-ether bonds in lignin and decrease in molecular weight of lignin. It should be noted that the cleavage of DB substructure brings about new PhOH groups into lignin [22], contributing to the observed increase.…”

Section: Resultsmentioning

confidence: 90%

“…The volume integration results indicated the β-O-4 as a main substructure in both MWL pur s. The signals of DB and SD substructures were observed in the HSQC spectrum of MWL pur of SM_AW with estimated amounts equal to 1.9% and 2.8%, respectively. It should be noted that the presence of DB substructure is reported sporadically for hardwood lignin [20,21]; the formation of DB in lignin depends strongly on the amounts of lignin precursors, coniferyl (converts to G-unit) and sinapyl (converts to S-unit) alcohol present during lignification of the cell wall (and hence, strong dependence of the amount of DB on the S/G ratio) [21,22]. The presence of DB substructure is observed more commonly in hardwood lignins formed as a result of genetically-modified biosynthesis [23].…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Comparative Analysis of Milled Wood Lignins (MWLs) Isolated from Sugar Maple (SM) and Hot-Water Extracted Sugar Maple (ESM)

2014

View full text Add to dashboard Cite

Abstract:To further elucidate the advantageous effects of hot-water extraction (HWE) on delignification, milled wood lignin (MWL) was isolated from sugar maple (SM) and from hot-water extracted sugar maple (ESM). Ball-milled wood was analyzed for particle size distribution (PSD) before and after dioxane:water (DW) extraction. The MWL samples were analyzed by analytical and spectral methods. The results indicated that the MWL isolated from SM and ESM was mainly released from the middle lamella (ML) and the secondary wall (SW), respectively. The cleavage of dibenzodioxocin (DB) and spirodienone (SD) lignin substructures during HWE is suggested. The removal of lignin during acetone:water (AW) extraction of hot-water extracted wood indicates that including an additional operation in a hardwood HWE-based biorefinery would be beneficial for processing of wood.

show abstract

OxidativeCCBond Formation (Couplings, Cyclizations, Cyclopropanation, etc.)

Dohi

Kita

2018

Patai's Chemistry of Functional Groups

View full text Add to dashboard Cite

Oxidative coupling that can directly convert CH group for chemical transformations is, in theory, an ideal strategy in organic synthesis as it reduces the number of synthetic steps and possible by‐products. Hypervalent iodine reagent has become one of the most promising tools in developing oxidative coupling due to its unique reactivity similar to metal oxidants. We have pioneered the metal‐free oxidative coupling chemistry using the hypervalent iodine reagents, that is, phenyliodine(III) diacetate (PIDA, PhI(OAc) 2 ) and bis(trifluoroacetate) (PIFA), in the past decades. As an introduction, we briefly mention the research backgrounds regarding the establishment of their fundamental reactivities with representative achievements in this area.

show abstract

Oxidative Coupling of Phenols and the Biosynthesis of Lignin

Cited by 81 publications

References 0 publications

Lignin Chemistry: Biosynthetic Study and Structural Characterisation of Coniferyl Alcohol Oligomers Formed In Vitro in a Micellar Environment

Lignin Chemistry: Biosynthetic Study and Structural Characterisation of Coniferyl Alcohol Oligomers Formed In Vitro in a Micellar Environment

Comparative Analysis of Milled Wood Lignins (MWLs) Isolated from Sugar Maple (SM) and Hot-Water Extracted Sugar Maple (ESM)

OxidativeCCBond Formation (Couplings, Cyclizations, Cyclopropanation, etc.)

Contact Info

Product

Resources

About