Asymmetric synthesis of 1-deoxynojirimycin and its congeners from a common chiral building block

A new, promising chiral building block for the synthesis of 1-deoxy-4,5-trans-oriented azasugars such as 1-deoxynojirimycin () was prepared in only four steps from the Garner aldehyde using catalytic ring-closing metathesis (RCM) for the construction of the piperidine ring. In practical test, the first synthesis of all four isomers ( and ) of trans-4,5-orientated 1-deoxyiminosugars using as a common chiral building block was demonstrated.