Zeolite-enhanced transfer hydrocyanation between nitriles and olefins: Expanding the conceptual utility of shape-selectivity in microporous catalysts.

Abstract

The catalytic shuttling of functional moieties has emerged as a promising strategy to substitute and diversify traditional hydrofunctionalization technologies. However, these reactions are reversible due to their isodesmic nature, which limits their applicability to a select array of donor and acceptor molecules, and poses significant challenges with regard to atom economy and practicality. Herein we show a new approach that harnesses the shape-selective and catalytic properties of zeolites to drive the shuttling equilibrium to near-completion. This strategy is demonstrated for transfer hydrocyanation and transfer hydroformylation reactions, showing yield increases up to 80% by the addition of a carefully selected zeolite. Clear improvements such as diversification of HCN-donors to e.g. propionitrile and the use of a simple reaction setup with mild conditions are achieved. The use of unstrained and unactivated olefins as HCHO-acceptors is demonstrated for the first time, significantly broadening the scope and utility of the transfer hydroformylation reaction. Mechanistic and spectroscopic studies highlight the unique synergy between the zeolites and the homogeneous transfer catalysts.