Mild Divergent Semi-Reductive Transformations of Secondary and Tertiary Amides via Zirconocene Hydride Catalysis

07 November 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

The mild catalytic partial reduction of amides to imines has proven to be a challenging synthetic transformation, with many transition metals directly reducing these substrates to amines. Herein, we report a mild, catalytic method for the semireduction of both secondary and tertiary amides via zirconocene hydride catalysis. Utilizing just 5 mol % of Cp2ZrCl2, the reductive deoxygenation of secondary amides is demonstrated to furnish a diverse array of imines in up to 94% yield with excel-lent chemoselectivity and without the need for glovebox handling. Moreover, a novel reductive transamination of tertiary amides is also achievable when the catalytic protocol is carried out in the presence of a primary amine at room temperature, providing access to an expanded assortment of imines. Through slight procedural modifications, the single-flask conversion of amides to imines, aldehydes, amines or enamines is feasible, including multicomponent syntheses.

Keywords

Zirconium
ZrH
Zirconocene Hydride
Amide
Transamination
Reduction
Imine

Supplementary materials

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Description
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Supporting Information
Description
General procedural information, mechanistic studies, characterization data and spectra
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