Peroxy zwitterions

The suggested fragments from (54a) are a carbonyl compound (58) and a peroxy zwitterion (59), the latter then effecting a 1,3-dipolar addition on the former to yield the ozonide (57a). Alternative reactions of the zwitterion (59), including its polymerisation, lead to the formation of the abnormal products that are sometimes observed in addition to the ozonide, If ozonolysis is carried out in MeOH as solvent then (59) is trapped , as it is formed, by its conversion into the relatively stable a-hydroperoxy ether (60) ... 

FIGURE 20. The transition states for peroxyformic acid zwitterion + ethylene (TS-a) and peroxy-formic acid + ethylene (TS-b) at the HF/6-31G and the MP2/6-31G level (in parentheses). The energy is at the MP4SDTQ//HF/6-31G level and MP4SDTQ//MP2/6-31G (in parentheses)... 

Zinc alkyls, 223 Zwitterions, 94,176 diazoanthranilate anion, 176 peroxy, 193... 

Some alkoxy-substituted dioxetanes yield a-peroxy ketones and esters via zwitterionic intermediates which are formed by heterolytic C-O bond cleavage as proven by trapping with acetaldehyde [135]. This behavior which has been fully explored by Jefford [135b], has been exploited for the total synthesis of the antimalarial (+)artemisinin [136a-c] and related analogs [136d-f]. One recent example is reported in Sch. 83 [136f ]. 

---