Flourat Amandine L, Peru Aurélien A M, Haudrechy Arnaud, Renault Jean-Hugues, Allais Florent
URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France.
Université de Reims Champagne Ardenne, CNRS, Institut de Chimie Moléculaire de Reims, UMR 7312, SFR Condorcet FR CNRS 3417, Reims, France.
Front Chem. 2019 Dec 9;7:842. doi: 10.3389/fchem.2019.00842. eCollection 2019.
To investigate lignin degradation, scientists commonly use model compounds. Unfortunately, these models are most of the time simple β--4 dimers and do not sufficiently mimic the wide complexity of lignin structure (i.e., aliphatic side chains and robust C-C bonds). Herein, we present a methodology to access advanced lignin models through the first synthesis of two trimers of monolignol -possessing side-chains and both robust β-5 bond and labile β--4 bond-via a chemo-enzymatic pathway. Key steps were (1) the C-C coupling via laccase-mediated oxidation, (2) the C-O coupling via a simple S between a phenolate and a bromoketoester, and (3) a modified Upjohn dihydroxylation or a palladium-catalyzed hydrogenation. (β-5)-(β--4) dihydroxytrimer and dihydrotrimer of coniferyl alcohol () were obtained in good global yield, 9 and 20%, respectively, over nine steps starting from ferulic acid.
为了研究木质素降解，科学家们通常使用模型化合物。不幸的是，这些模型大多时候只是简单的β-4二聚体，无法充分模拟木质素结构的广泛复杂性（即脂肪族侧链和稳定的C-C键）。在此，我们展示了一种方法，通过化学酶促途径首次合成两种具有侧链的单木质醇三聚体，同时含有稳定的β-5键和不稳定的β-4键，从而获得高级木质素模型。关键步骤包括：（1）通过漆酶介导的氧化进行C-C偶联；（2）通过酚盐和溴代酮酯之间简单的S进行C-O偶联；（3）改良的Upjohn双羟基化反应或钯催化的氢化反应。从阿魏酸开始经过九步反应，分别以9%和20%的总产率得到了（β-5）-（β-4）二羟基三聚体和松柏醇二氢三聚体。
