Flow chemistry based catalytic hydrogenation for improving the synthesis of 1-deoxynojirimycin (DNJ) from an l-sorbose derived precursor

1-Deoxynojirimycin (1-DNJ) is a glycoprocessing inhibitor, and it serves as a synthetic precursor to two of three currently marketed iminosugar drugs, miglustat (N-butyl DNJ/Zavesca®) and miglitol (Glyset®). Herein a continuous flow procedure is presented that shortens a synthesis of 1-DNJ from an intermediate prepared from l-sorbose. Batch reactions involving an azide reduction, subsequent reductive amination-based cyclisation, and O-benzyl deprotection in a previous report required two steps and the use of an acid. Here, this sequence is achieved in one step using the H-Cube® MiniPlus continuous flow reactor. Subsequent reductive amination of 1-DNJ with butanal using the H-Cube® gave NB-DNJ. [Display omitted] •Continuous flow synthesis of 1-DNJ from an l-sorbose derivative.•Improved yield, reaction time and safety.•First flow synthesis of miglustat (Zavesca®).