Density Functional Theory Computational Study on the Thermal Cycloreversion of 2-Acetoxy-2-methoxy-5,5-dimethyl-Δ3-1,3,4-oxadiazoline: Evidence for a Carbonyl Ylide Intermediate

Three [3 + 2] cycloreversions of 2-acetoxy-2-methoxy-5,5-dimethyl-Delta(3)-1,3,4-oxadiazolines were examined by computation at the density functional level of theory. The lowest activation energies are those for cycloreversion to 2-diazopropane and acetic methylcarbonic anhydride and for cycloreversion to N(2) and a carbonyl ylide. Those are the reactions that are observed experimentally. A third cycloreversion, to acetoxy(methoxy)diazomethane …