Oxidative Ring‐Expansion of a Chitin‐Derived Platform Enables Access to Unexplored 2‐Amino Sugar Chemical Space

Abstract

The chitin obtained from crustacean shell waste and other renewable resources may be used as a primary feedstock in the biorefineries of the future. Accordingly, the incorporation of chitin‐derived building blocks into new synthesis processes will accentuate the utility of this biopolymer, particularly in the production of bio‐based small molecules that contain one or more nitrogen atoms. Herein we report that enantioenriched 2‐amino sugars are readily accessible from the chitin‐derived platform 3‐acetamido‐5‐acetylfuran (3A5AF). Subjecting 3A5AF to a Noyori reduction–Achmatowicz rearrangement sequence gave N‐acetyl‐l‐rednose (RedNAc) in excellent yield and enantiopurity. Acetamide hydrolysis gave l‐rednose, a rare 2‐amino sugar found in natural anthracycline and angucycline antibiotics. RedNAc was subsequently shown to be a versatile platform from which a variety of stereochemically pure 2‐amino sugars are readily attainable. The synthesis of chiral, bio‐based N‐compounds from chitin emphasises the rapidly expanding utility of this biopolymer as a viable platform for fine chemical production.