170302-17-7Relevant academic research and scientific papers
Preparation of Unsymmetrically Labeled Hydroperoxides. a Hydroxamate Ester-Nitrosation Approach
Porter, Ned A.,Caldwell, Sarah E.,Lowe, Jennifer R.
, p. 5547 - 5554 (1998)
Reaction of O-tertiary alkyl arylhydroxamate esters with nitrosyl chloride gives O-tertiary alkyl aryl peresters that can be hydrolyzed to the hydroperoxide. If the hydroxamate ester carbonyl oxygen or nitrosyl chloride is labeled with 18O, the label appears in the product hydroperoxide's terminal oxygen. This strategy, which derives from the pioneering work of Koenig, permits the preparation of a variety of (2-18O) hydroperoxides, including tertiary alkyl and cumyl hydroperoxides. tert-Butyl α-hydroperoxyisobutyrate, 27, prepared in this way with an 18O label in the terminal oxygen, serves as a useful precursor for the preparation of other unsymmetrically labeled peroxides and hydroperoxides. Hydroperoxide 27 is protected as a perketal with 2-methoxypropene, and a six-step sequence involving Dibal-H reduction, oxidation (PDC), and Wittig chemistry provides the allylic hydroperoxide 12 that is used in mechanistic studies. Hydroxamate esters that give peresters prone to undergo the Criegee rearrangement upon reaction with NOCI do not give useful yields of product hydroperoxides in the transformation and one hydroxamate ester 17 that reacts via an allylalkoxyl radical gives epoxides 2Oa and 2Ob as the major isolable products of reaction.
