Iron-Based Deep Eutectic Solvents: Versatile and Powerful Tools in Sustainable Organic Synthesis.

Deep Eutectic Solvents (DESs) based on abundant and non-toxic first-row metals have emerged as versatile and sustainable alternatives to conventional solvents/promoters in a variety of synthetic organic protocols under greener and milder reaction conditions. In particular, Fe(III)-based Lewis Acidic DESs (LADESs) have recently shown great potential as dual solvent/promoter systems enabling efficient transformations under air and recyclable conditions without requiring toxic volatile organic compound (VOC) solvents at any stage in the protocol (synthesis, isolation or purification). Specifically, in this short review, we summarize our recent progress in the application of FeCl3-based DESs as sustainable and efficient promoters/solvents in organic synthesis by presenting two representative examples: i) the hydration and hydration/oxidation of terminal or internal alkynes to yield methyl ketones or 1,2-diketones, respectively; and ii) the Friedel-Crafts benzylation reaction. The performance, recyclability, mechanistic features and green metrics for these processes are discussed, highlighting the promise of this approach for sustainable synthesis.