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Metal-free borylative dearomatization of indoles: exploring the divergent reactivity of aminoborane C-H borylation catalysts.

ABSTRACT: While the dearomatization of indoles by carbon-boron bond forming reactions is new and quite promising, they are so far mainly metal-catalyzed. Here, we establish the use of metal-free catalysts in promoting such reactions in an atom-efficient way. The in situ generated ambiphilic aminoborane catalyst (1-Pip-2-BH₂-C₆H₄)₂ (Pip = piperidyl) promotes borylative dearomatization of various 1-arylsulfonyl indoles with pinacolborane in a syn addition fashion, with H and Bpin groups added respectively to the 2 and 3 positions of indoles. Catalysis proceeds with good to excellent conversion and essentially with complete regio- and diastereoselectivity. From mechanistic insights and DFT computations, we realized and established that prototypical boranes can also catalyze this borylative dearomatization.

SUBMITTER: Jayaraman A

PROVIDER: S-EPMC5994747 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Metal-free borylative dearomatization of indoles: exploring the divergent reactivity of aminoborane C-H borylation catalysts.

Jayaraman Arumugam A Misal Castro Luis C LC Desrosiers Vincent V Fontaine Frédéric-Georges FG

Chemical science 20180507 22

While the dearomatization of indoles by carbon-boron bond forming reactions is new and quite promising, they are so far mainly metal-catalyzed. Here, we establish the use of metal-free catalysts in promoting such reactions in an atom-efficient way. The in situ generated ambiphilic aminoborane catalyst (1-Pip-2-BH2-C6H4)2 (Pip = piperidyl) promotes borylative dearomatization of various 1-arylsulfonyl indoles with pinacolborane in a syn add ...[more]

PMID: 29938036

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