Reactions of levoglucosenone and its derivatives with diazo compounds

Abstract

The reaction of levoglucosenone with methyl diazoacetate gives first 1-pyrazoline, which then, depending on the reaction conditions, either undergoes denitrogenation to form a mixture of cyclopropane and unsaturated compounds, or isomerizes into 2-pyrazoline capable of easy cyclodimerizing in the presence of pyridine through the addition of the N—H fragments to the carbonyl groups. The product of levoglucosenone reduction, 6,8-dioxabicyclo [3.2.1]oct-2-en-4-ol, affords the corresponding cyclopropane upon the action of diazomethane in the presence of a Pd catalyst, whereas its reaction with methyl diazoacetate in the presence of Rh 2 (OAc) 4 leads to the insertion of methoxycarbonyl carbene into the OH bond. From the ester obtained, l-diazo-3-6,8-dioxabicyclo[3.2.1]oct-2-en-4-yloxypropan-2-one was synthesized in several steps, its denitrogenation under the action of copper compounds is accompanied by the intramolecular insertion of the carbene into the C(4)—H bond of the levoglucosenone fragment to yield the corresponding spirane.