5,5'-Bis(hydroxymethyl)-3,3'-dimethoxybiphenyl-2,2'-diol with a new three-dimensional 3-modal topology of synthons.

The title lignin model compound, C(16)H(18)O(6), resides on a twofold axis parallel with the b axis, with the mid-point of the internal C-C(-x + 1, y, -z + 1/2) bond located on the twofold axis. The exo angles between the methoxy groups and the benzene rings deviate significantly from the expected value of 120° [125.15 (7) and 114.

Oxidation of the erythro and threo forms of the phenolic lignin model compound 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol by laccases and model oxidants.

Mixtures of equal amounts of the erythro and threo forms of the phenolic arylglycerol beta-aryl ether 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol were oxidized (i) with laccases from Trametes versicolor, Agaricus bisporus, Myceliophthora thermophila and Rhus vernicifera, (ii) with laccase-mediator systems consisting of T. versicolor laccase and ABTS or HBT, and (iii) with various model oxidants including cerium(IV) ammonium nitrate (CAN), lignin peroxidase, Fenton's reagent, and lead(IV) tetraacetate (LTA). All the laccases exhibited a similar preferential degradation of the threo form.

Conformation of 1-aryl-2-aryloxy-1-propanols: threo-1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-1-propanol.

The title compound, C(17)H(20)O(5), (I), is structurally related to naturally occurring 1-aryl-2-aryloxy-1-propanols. Such compounds are of interest as lignin models, and neolignans of this type have been detected in a large number of plants. In the crystal structure of (I), the molecules adopt a conformation in which the aryl groups are far apart from each other.

Stereoisomers of 1,2-diaryl-1,3-propanediols: erythro forms.

Racemic erythro-1,2-diphenyl-1,3-propanediol, C(15)H(16)O(2), is a model compound representative of erythro forms of structural elements of the 1,2-diaryl-1,3-propanediol type in lignins. In the crystal structure, the torsion angle between the bulky phenyl groups is -62.26 (11)degrees.

2,3-Diaryl-3-hydroxypropionic acid intermediates in the synthesis of threo forms of 1,2-diaryl-1,3-propanediols.

Racemic threo-3-hydroxy-2,3-diphenylpropionic acid, C15H14O3, (I), crystallizes from ethyl acetate as a conglomerate of separate (+)- and (-)-crystals. The geometries of (I) and its methyl ester are compared. Reduction of (I) gives threo-1,2-diphenyl-1,3-propanediol.

Chalcone epoxide intermediates in the syntheses of lignin-related phenylcoumarans.

Compounds (2R*,3S*)-1-(3,4-dimethoxyphenyl)-3-{3-methoxy-2-[(2R*)-tetrahydropyran-2-yloxy]phenyl}-2,3-epoxy-1-propanone, C23H26O7, (I), and trans-1-(3,4-dimethoxyphenyl)-3-[3-methoxy-2-(methoxymethoxy)phenyl]-2,3-epoxy-1-propanone, C20H22O7, (II), were obtained on epoxidation of chalcones. The stereochemistries of (I) and (II) were elucidated. In both compounds, the substituents on the oxirane ring are trans-oriented.

Oxidation capacity of laccases and peroxidases as reflected in experiments with methoxy-substituted benzyl alcohols.

A set of methoxy-substituted benzyl alcohol (MBA) congeners were examined regarding susceptibility to oxidation by Trametes versicolor laccase, T. versicolor lignin peroxidase and horseradish peroxidase: 2,4,5-trimethoxybenzyl alcohol (TMBA), 3,4,5-TMBA, 2,3,4-TMBA, 2,5-dimethoxybenzyl alcohol (DMBA), 3,4-DMBA, and 2,3-DMBA. The corresponding methoxy-substituted benzaldehydes were strongly predominant as products on enzymic oxidation.

13C assignments of the carbon atoms in the aromatic rings of lignin model compounds of the arylglycerol beta-aryl ether type.

The 13C NMR signals from the aromatic ring carbons in a series of lignin model compounds of the arylglycerol beta-aryl ether type in DMSO solution have been assigned. The model compounds investigated are representative of the erythro and threo forms of differently substituted arylglycerol beta-aryl ethers.

threo-2-(2,6-dimethoxyphenoxy)-1-(4-hydroxy-3,5-dimethoxyphenyl)propane-1,3-diol: a conformational study.

In the crystal structure of the title compound, C19H24O8, the molecules adopt a conformation in which the bulky 2,6-dimethoxyphenoxy and 4-hydroxy-3,5-dimethoxyphenyl groups are almost as far apart as possible. The C(aryl)..