Ozonolysis of Bicyclic 1,2-Dioxines: Initial Scope and Mechanistic Insights

The ozonolysis of bicyclic 1,2-dioxines was investigated
using a variety of 1,4-disubstituted 1,2-dioxines along with a 1,3-dialkyl
and steroidal example, with yields ranging from moderate to excellent.
Two different pathways were observed upon reaction of the 1,4-disubstituted
1,2-dioxines with ozone; one pathway saw the “expected”
results, that is, cleavage of the olefinic moiety with generation
of 1,4-dicarbonyl 1,2-dioxines, while the other pathway revealed a
previously unobserved rearrangement involving cleavage of the peroxide
linkage along with loss of either CO or CO2. Several unsymmetrical
ozonolyses were also performed to further investigate the origins
of this rearrangement, and initial mechanistic insights into the fragmentation
pathways are discussed.