Surface Decoration of Cellulose With Trifluoromethylphenyl Substituted Thiourea: A Robust Hydrogen‐Bonding Catalyst in Conjunction With L‐Proline for the Asymmetric Direct Mannich Reaction

• Published in: Biopolymers Vol. 116; no. 1; pp. e23647 - n/a
• Main Authors: Poslu, Ayşe Haliç, Koz, Gamze
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.01.2025; Wiley Subscription Services, Inc
• Subjects: Aldehydes; Aniline; Aniline Compounds - chemistry; asymmetric Mannich reaction; Asymmetric synthesis; Asymmetry; Biopolymers; Catalysis; Catalysts; Cellulose; Cellulose - chemistry; Chemical reactions; Chemical synthesis; Chitosan; Cooperation; Enantiomers; Fourier transforms; Hydrogen Bonding; Hydrogen bonds; Infrared spectroscopy; L‐proline; Magnetic resonance spectroscopy; NMR; NMR spectroscopy; Nuclear magnetic resonance; organocatalysis; Proline; Proline - chemistry; Robustness; Room temperature; Scanning electron microscopy; Spectroscopy, Fourier Transform Infrared; Spectrum analysis; Stereoisomerism; Substitution reactions; Thermal analysis; Thermogravimetric analysis; Thiourea; Thiourea - chemistry; Thioureas; organocatalysis; asymmetric Mannich reaction; thiourea; cellulose; L‐proline
• ISSN: 0006-3525; 1097-0282; 1097-0282
• DOI: 10.1002/bip.23647

ABSTRACT Cellulose is one of the most abundant biopolymers in nature. Despite being the subject of research in various fields, it is not as famous as chitosan in catalyst design. Herein, a novel thiourea‐functionalized cellulose (CTU‐6) was synthesized as a robust hydrogen bonding catalyst with the degree of substitution (DS) of 0.84. CTU‐6 was characterized using Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscope (SEM), x‐ray powder diffraction (XRD), proton nuclear magnetic resonance spectroscopy (1HNMR), solid‐state cross‐polarization magic angle spinning carbon‐13 nuclear magnetic resonance (CP/MAS 13C‐NMR), thermal gravimetric analysis (TGA) and elementel analysis. CTU‐6 catalyzed the direct asymmetric Mannich reaction between acetone, aniline, and various aromatic aldehydes in cooperation with L‐proline. The reaction exhibited excellent enantioselectivity, achieving up to 98% enantiomeric excess (ee) at room temperature. Incorporating trifluoromethylphenyl‐substituted thiourea into the cellulose framework leverages its ability to form hydrogen bonds, thereby enabling precise control over the asymmetric induction. This study highlights the potential of cellulose‐based catalysts in advancing asymmetric synthesis and their versatility in various organic reactions in cooperation with small chiral ligands. This synergy not only facilitates the efficient catalytic process but also improves the stereochemical outcomes of the reactions. This method underscores the importance of utilizing renewable and versatile cellulose materials in combination with chiral auxiliaries to achieve high levels of enantioselectivity.