Sustainable Hydrogen Borrowing Catalysis in Deep Eutectic Solvents: Towards Greener C–N Bond Formation

The development of sustainable catalytic methodologies is a cornerstone of modern green chemistry. Among these, hydrogen borrowing has emerged as a particularly appealing strategy: it enables the use of alcohols as alkylating agentsthrough a catalytic sequence of oxidation, condensation, and reduction, mediated by a suitable metal catalyst (Figure 1) [1,2]. Despite their synthetic utility, such transformations traditionally rely on rare and expensive transition metals and require harsh reaction conditions, which limit both their environmental compatibility and industrial scalability. Deep eutectic solvents (DESs) are increasingly recognized as green and versatile reaction media in both catalytic and stoichiometric chemistry. Formulated from biodegradable and renewable components, DESs offer tunable physicochemical properties, making them ideal for promoting and modulating catalytic transformations [3]. This project focuses on implementing hydrogen borrowing strategies for C–N bond formation, using alcohols and amines as in situ hydrogen donors, within DES-based reaction systems. By incorporating selected DESs—with or without the use of earth-abundant metals—this research aims to overcome the limitations of conventional protocols, enhancing substrate scope, reaction efficiency, and selectivity under milder and more sustainable conditions. Beyond reducing the environmental impact, this approach has the potential to unlock new reactivity paradigms, contributing to a more sustainable and innovative future for synthetic chemistry.