Peroxometallacycle intermediate

Pd(H) fcrf-butyl peroxidic complexes of the general formula [RCOOPdOOferf-Bu]4 are very efficient reagents for the selective stoichiometric oxidation of terminal alkenes in anhydrous nonbasic organic solvents at ambient temperature.518 They also catalyze the ketonization by tert-BuOOH. Internal olefins are not reactive at all. A peroxometallacycle intermediate (see discussion below) was suggested. 

Deuterium labeling experiments indicate that ketone formation involves a peroxometallacycle intermediate, but epoxidation occurs via a different path [174]. 

Peroxometallacycles are also regarded as active intermediates in olefin epoxidation by diperoxomolybdenum(VI) and related reagents (cf. section 3.1.1. ). 

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