First Total Synthesis of (β-5)-(β- O-4) Dihydroxytrimer and Dihydrotrimer of Coniferyl Alcohol (G): Advanced Lignin Model Compounds

Amandine L Flourat; Aurélien A M Peru; Arnaud Haudrechy; Jean-Hugues Renault; Florent Allais

doi:10.3389/fchem.2019.00842

First Total Synthesis of (β-5)-(β- O-4) Dihydroxytrimer and Dihydrotrimer of Coniferyl Alcohol (G): Advanced Lignin Model Compounds

Front Chem. 2019 Dec 9:7:842. doi: 10.3389/fchem.2019.00842. eCollection 2019.

Authors

Amandine L Flourat^{1

2}, Aurélien A M Peru¹, Arnaud Haudrechy², Jean-Hugues Renault², Florent Allais¹

Affiliations

¹ URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France.
² Université de Reims Champagne Ardenne, CNRS, Institut de Chimie Moléculaire de Reims, UMR 7312, SFR Condorcet FR CNRS 3417, Reims, France.

Abstract

To investigate lignin degradation, scientists commonly use model compounds. Unfortunately, these models are most of the time simple β-O-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 G-possessing side-chains and both robust β-5 bond and labile β-O-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_N2 between a phenolate and a bromoketoester, and (3) a modified Upjohn dihydroxylation or a palladium-catalyzed hydrogenation. (β-5)-(β-O-4) dihydroxytrimer and dihydrotrimer of coniferyl alcohol (G) were obtained in good global yield, 9 and 20%, respectively, over nine steps starting from ferulic acid.

Keywords: C-C coupling; biocatalysis; coniferyl alcohol; laccase; lignin models; monolignol; total synthesis; trimers.