Reaction of levoglucosenone with diazocyclopropane

Abstract

Depending of the reaction conditions, reaction of levoglucosenone with diazocyclopropane generated in situ from N cyclopropyl N nitrosourea under the action of bases involved either the carbonyl group to give oxaspiropentane (MeONa/MeOH, -30 °C), or the double C=C bond to give 1 pyrazoline (K 2 CO 3 , CH 2 Cl 2 , 5 °C). The latter readily reacted with diazocyclo propane at the C=O group or added as a C nucleophile in a regio and stereoselective Michael reaction to the C=C bond of levoglucosenone. The direction of reaction depended on the reactant ratio. The reaction of the levoglucosenone-diazomethane adduct with an excess of levoglucosenone in the presence of a base yielded similar product bearing two levoglucosenone moieties.