Mechanism of the dehydration of N-acetyl-d-glucosamine into N-containing platform molecule 3-acetamido-5-acetylfuran: NMR study.

Using NMR technology with the aid of ESI-mass spectroscopy to investigate the reaction of the dehydration of GlcNAc into 3A5AF and propose the reasonable mechanism. [Display omitted] • [AMim]Cl and B(OH) 3 synergistically catalyze GlcNAc to produce 3A5AF. • The interaction between the catalysts and GlcNAc was explored by 1H, 13C &35Cl chemical shift titration. • The reaction intermediates Chromogen I and Chromogen III were detected by NMR and ESI-MS. • The reaction mechanism and path were proposed through NMR results and DFT calculations. This study proposed that the preparation of 3-acetamido-5-acetylfuran (3A5AF), a versatile platform molecule, from N -acetyl- d -glucosamine (GlcNAc) catalyzed by boric acid (B(OH) 3) and 1-allyl-3-methylimidazolium chloride ([AMim]Cl). Herein, the mechanism was investigated by primary nuclear magnetic resonance (NMR) technology. The catalytic interactions between [AMim]Cl/B(OH) 3 and GlcNAc were investigated by 1H, 13C &35Cl chemical shift titration. In addition, 13C 1 -labelled GlcNAc and various NMR techniques were exploited to characterize the reaction at the molecular level and detect the reaction intermediates. The results revealed that the chloride ion and the boron complex of GlcNAc with B(OH) 3 probably play crucial roles and are responsible for a synergic catalytic effect in the process. The intermediates, 2-acetamido-2,3-dideoxy- d - erythro -hex-2-enofuranose (Chromogen I) and 3-acetamido-5-(1′,2′-dihydroxyethyl)furan (Chromogen III), were recognized by NMR and further confirmed with the aid of ESI-mass spectroscopy. On the basis of these studies a reaction pathway could be proposed. [ABSTRACT FROM AUTHOR]