Short path syntheses of α-diozonides by sequential ozonolyses of acetylenes and O-methyl oximes

Ozonolyses of but-2-yne 1 in the presence of added carbonyl compounds 3 afford a-oxo ozonides 4. Subsequent cycloadditions between ozonides 4 and cyclohexanone oxide 6, generated in situ by ozonolysis of O-methylcyclohexanone oxime, yield in turn a-diozonides 7 into which have been incorporated the carbon skeletons of all three substrates involved. Ozonolyses of acyloxy-substituted but-2-ynes 9 yield the corresponding bicyclic a-oxo ozonides 11 which subsequently participate in analogous cycloadditions with 6 to produce the corresponding a-diozonides 12. X-Ray crystallographic analysis of the crystalline diozonide 12a shows that it has been formed exclusively by exo-addition of 6 to 11a.