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Selective benzylic C-H monooxygenation mediated by iodine oxides.

ABSTRACT: A method for the selective monooxdiation of secondary benzylic C-H bonds is described using an N-oxyl catalyst and a hypervalent iodine species as a terminal oxidant. Combinations of ammonium iodate and catalytic N-hydroxyphthalimide (NHPI) were shown to be effective in the selective oxidation of n-butylbenzene directly to 1-phenylbutyl acetate in high yield (86%). This method shows moderate substrate tolerance in the oxygenation of substrates containing secondary benzylic C-H bonds, yielding the corresponding benzylic acetates in good to moderate yield. Tertiary benzylic C-H bonds were shown to be unreactive under similar conditions, despite the weaker C-H bond. A preliminary mechanistic analysis suggests that this NHPI-iodate system is functioning by a radical-based mechanism where iodine generated in situ captures formed benzylic radicals. The benzylic iodide intermediate then solvolyzes to yield the product ester.

SUBMITTER: LaMartina KB

PROVIDER: S-EPMC6423598 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Selective benzylic C-H monooxygenation mediated by iodine oxides.

LaMartina Kelsey B KB Kuck Haley K HK Oglesbee Linda S LS Al-Odaini Asma A Boaz Nicholas C NC

Beilstein journal of organic chemistry 20190305

A method for the selective monooxdiation of secondary benzylic C-H bonds is described using an N-oxyl catalyst and a hypervalent iodine species as a terminal oxidant. Combinations of ammonium iodate and catalytic N-hydroxyphthalimide (NHPI) were shown to be effective in the selective oxidation of n-butylbenzene directly to 1-phenylbutyl acetate in high yield (86%). This method shows moderate substrate tolerance in the oxygenation of substrates containing secondary benzylic C ...[more]

PMID: 30931001

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