The transformation of cyclopentadiene to 5′-desmethylene 1′-aza carbocyclic sugars has been achieved in four steps: 1. Cycloaddition of chloronitrosocyclohexane to 2-aza-3- oxabicyclo [2.2. 1] heptene hydrochloride in EtOH-Et2O, 2. Nitrogen functiona-lization, 3. cis hydroxylation and 4. N O bond cleavage. The protocols provided enable practical access to a range of 5′-desmethylene carbocyclic sugar analogs whose utility has been ...