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Chiral Bronsted base-promoted nitroalkane alkylation: enantioselective synthesis of sec-alkyl-3-substituted indoles.

ABSTRACT: A Brønsted base-catalyzed reaction of nitroalkanes with alkyl electrophiles provides indole heterocycles substituted at C3 bearing a sec-alkyl group with good enantioselectivity (up to 90% ee). Denitration by hydrogenolysis provides a product with equally high ee. An indolenine intermediate is implicated in the addition step, and surprisingly, water cosolvent was found to have a beneficial effect in this step, leading to a one-pot protocol for elimination/enantioselective addition using PBAM, a bis(amidine) chiral nonracemic base.

SUBMITTER: Dobish MC

PROVIDER: S-EPMC3005818 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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Chiral Brønsted base-promoted nitroalkane alkylation: enantioselective synthesis of sec-alkyl-3-substituted indoles.

Dobish Mark C MC Johnston Jeffrey N JN

Organic letters 20101119 24

A Brønsted base-catalyzed reaction of nitroalkanes with alkyl electrophiles provides indole heterocycles substituted at C3 bearing a sec-alkyl group with good enantioselectivity (up to 90% ee). Denitration by hydrogenolysis provides a product with equally high ee. An indolenine intermediate is implicated in the addition step, and surprisingly, water cosolvent was found to have a beneficial effect in this step, leading to a one-pot protocol for elimination/enantioselective addition using PBAM, a ...[more]

PMID: 21090654

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