Unexpected transformations: from 5-glyco-4-nitrocyclohexenes to bicyclic [3.3.1] oximes through isoxazoline N-oxides

Treatment of 5-glyco-4-nitrocyclohexenes with excess or equimolar sodium methoxide gave deacetylated sodium nitronates which, on reaction with Ac2O/py, led to chiral isoxazoline N-oxides (cyclic nitronic esters). Depending on the configuration of their respective sugar side-chains, base-catalyzed deacetylation of these nitronate esters yielded either a bicyclic [3.3.1] oxime or a deacetylated isoxazoline N-oxide.