DURABLE CHIRAL GRAPHITE ELECTRODES MODIFIED CHEMICALLY WITH POLY(l-VALINE) AND POLY(N-ACRYLOYL-l-VALINE METHYL ESTER)

Abstract

Graphite electrodes modified chemically with poly(l-valine) and poly(N-acryloyl-l-valine methyl ester) were prepared. They were remarkably more durable than the corresponding dip-coated electrodes when used repeatedly in the electrochemical asymmetric reduction of citraconic acid.

Asymmetric Catalysis Mediated by Synthetic Peptides, Version 2.0: Expansion of Scope and Mechanisms

“…Prior to 2007, peptide-based catalysts had been demonstrated only sporadically in asymmetric reductions of various functional groups. Among the earliest contributions were electrochemical reductions, wherein polypeptide-coated electrodes were employed to enable asymmetric induction during electron transfer events. − Since then, numerous advances have been made in the application of both solution-phase and resin-supported peptide catalysts toward the reductions of ketones, imines, quinolines, and conjugated alkenes, often with high levels of enantiocontrol. In particular, three classes of peptides have emerged as excellent platforms for such processes, including (1) amine-containing peptides via iminium catalysis, (2) phosphothreonine (pThr)-containing peptides for Brønsted acid catalysis, and (3) various peptidic ligands in metal-based reduction systems (Section ).…”

Asymmetric Catalysis Mediated by Synthetic Peptides

“…After one use, the poly-L-valine dip-coated graphite electrodes begin to degrade and exhibit lower enantioselectivity in subsequent runs. 124 To address this durability problem, Nonaka investigated chemically modified electrodes. Graphite plates were treated with 1,3-diaminopropane and then exposed to L-valine NCA.…”

“…Under similar conditions, 4-methylcoumarin ( 59 ) may be enantioselectively reduced to provide 60 in 8% yield, with 43% ee. After one use, the poly- l -valine dip-coated graphite electrodes begin to degrade and exhibit lower enantioselectivity in subsequent runs . To address this durability problem, Nonaka investigated chemically modified electrodes.…”

The synthesis and structure of

“…We also have an interest in exploring the electrochemistry of chiral surfaces (7,8). For these reasons the synthesis of l c , which contains both a chiral center and planar chirality, and its binding to silica, was an attractive target since, if necessary, it could readily be prepared as an optically pure enantiomer (9,10).…”