A BIOMIMETIC ROUTE TO LIGNIN MODEL COMPOUNDS VIA SILVER (I) OXIDE OXIDATION .2. NMR CHARACTERIZATION OF NONCYCLIC BENZYL ARYL ETHER TRIMERSAND TETRAMERS

The non-cyclic alpha-O-4 benzyl aryl ethers, erythro-guaiacylglycerol- alpha,beta-bis-coniferyl ether, -alpha-dehydrodiconiferyl-beta-conifer yl-bis-ether and ycerol-alpha-pinoresinol-beta-coniferyl-bis-ether, is olated from the silver(I) oxide-mediated oxidative coupling of conifer yl alcohol in aqueous solutions, were fully characterized by the use o f 1D and 2D NMR techniques. The application of 2D HMQC-TOCSY and delay ed COSY experiments were found to be a useful complement and/or altern ative to the application of the usual routine 2D homo- and heteronucle ar correlation experiments for the structural elucidation and chemical shift assignments of these oligomeric lignols.