Formation of an endoperoxide upon chromium-catalyzed allylic oxidation of a triterpene by oxygen

Abbie Chung, Matthew R. Miner, Kathleen J. Richert, Curtis J. Rieder, Keith Woerpel

Research output: Contribution to journalArticle

Abstract

The chromium-catalyzed allylic oxidation of triterpene 1 with O2 and N-hydroxyphthalimide (NHPI, 5 equiv) formed endoperoxide 2 in 76% yield at ambient temperature. Unlike standard allylic oxidations, this oxidation is catalytic in chromium because oxygen, not the chromium reagent, is the oxidant. This oxidation is sensitive to the precise structure of the substrate. The endoperoxide is only formed if ring A is unsaturated and ring C contains an enone. A mechanism is proposed that involves the coupling of two stabilized radicals on rings A and C to form endoperoxide 2.

Original languageEnglish (US)
Pages (from-to)266-273
Number of pages8
JournalJournal of Organic Chemistry
Volume80
Issue number1
DOIs
StatePublished - 2015

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Triterpenes
Chromium
Oxygen
Oxidation
Catalytic oxidation
Oxidants
Substrates
Temperature

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Formation of an endoperoxide upon chromium-catalyzed allylic oxidation of a triterpene by oxygen. / Chung, Abbie; Miner, Matthew R.; Richert, Kathleen J.; Rieder, Curtis J.; Woerpel, Keith.

In: Journal of Organic Chemistry, Vol. 80, No. 1, 2015, p. 266-273.

Research output: Contribution to journalArticle

Chung, Abbie ; Miner, Matthew R. ; Richert, Kathleen J. ; Rieder, Curtis J. ; Woerpel, Keith. / Formation of an endoperoxide upon chromium-catalyzed allylic oxidation of a triterpene by oxygen. In: Journal of Organic Chemistry. 2015 ; Vol. 80, No. 1. pp. 266-273.
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