The synthesis of a series of six‐membered 2‐acetamido l‐iminosugar C‐alkyl and C‐aryl glycosides is reported. A diastereoselective sugar‐ring enlargement/C‐alkylation (or arylation) /ring‐contraction sequence applied to d‐gluco‐ and d‐manno‐configured 2‐acetamido azidolactols provides new l‐iminosugar C‐glycosides. The 1,2‐trans stereocontrolled introduction of the pseudoanomeric substituent in these heterocycles strongly suggests a NHAc neighbouring‐group participation. In their deprotected form, the nine iminosugars exhibit moderate hexosaminidases and β‐glucuronidase inhibition.