Direct conversion of esters to imines/enamines and applications to polyester waste upcycling.

Semi-reductive transformations of esters remain an underdeveloped but valuable class of functional group interconversions. Here, we describe the development of a highly selective method for the interconversion of esters to imines, enamines, aldehydes or amines through an amine-intercepted zirconocene hydride (ZrH)-catalyzed reduction. This protocol employs an inexpensive zirconium catalyst in combination with hydrosilanes and simple unprotected amines.

Mild Divergent Semireductive Transformations of Secondary and Tertiary Amides via Zirconocene Hydride Catalysis.

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 CpZrCl, the reductive deoxygenation of secondary amides is demonstrated to furnish a diverse array of imines in up to 94% yield with excellent chemoselectivity and without the need for glovebox handling.

Expanding Zirconocene Hydride Catalysis: Generation and Turnover of ZrH Catalysts Enabling Catalytic Carbonyl Reductions.

Despite the wide use and popularity of metal hydride catalysis, methods utilizing zirconium hydride catalysts remain underexplored. Here, we report the development of a mild method for the preparation and use of zirconium hydride catalysts. This robust method requires only 2.