A Biocatalytic Cascade for the Valorisation of Sugars.

Biocatalytic cascades offer products of multistep synthesis without the use of protecting groups or isolation of intermediates. This strategy is particularly amenable to the synthesis of iminosugars, where traditional routes typically suffer from lengthy and inefficient steps. We have developed a one‐pot, three‐step biocatalytic cascade to synthesize trihydroxypiperidine and azepane iminosugars directly from monosaccharides, employing transaminase and galactose oxidase (GOase) enzymes. An in‐situ LC/MS method for monitoring the key reaction intermediates that have never been observed was also developed.