[1,3]-Dipolar intramolecular nitrone olefin cycloaddition reaction of a sugar-derived α,β-unsaturated ester: a new diastereo- and regioselective synthesis of an aminocyclopentitol

The reaction of hemiacetal 2a, from the sugar derived α,β-unsaturated ester 1a, with N-benzylhydroxylamine hydrochloride in situ generates an N-benzylnitrone as a 1,3-dipole, which spontaneously undergoes diastereo- and regioselective intramolecular nitrone olefin cycloaddition to afford a hydroxy functionalised 4-exo-ethoxycarbonyl-3-oxa-2-azabicyclo[3.3.0]octane system, a precursor to a hitherto unknown aminocyclopentitol derivative.