Deep eutectic solvents (DES) as green reaction media for the redox isomerization of allylic alcohols into carbonyl compounds catalyzed by the ruthenium complex [Ru(η3:η3-C10H16)Cl2(benzimidazole)]

•Use of Deep Eutectic Solvents as green media in metal-catalyzed organic reactions.•Complex 1c is an active catalyst for the isomerization of allylic alcohols in DES.•Isomerization reaction takes place in the absence of base and in large-scale.•The catalytic system was recycled up to four consecutive runs.

The bis-allyl Ru(IV) complex [Ru(η3:η3-C10H16)Cl2(benzimidazole)] (1c) is an active catalyst in the redox isomerization of allylic alcohols into saturated carbonyl compounds using, for the first time, Deep eutectic solvents (DES) as reaction media. A series of primary and secondary allylic alcohols could be isomerized into the corresponding carbonyl compounds in the absence of base. Although high activities and selectivities were reached at short reaction times and with low catalyst loadings (0.2 mol% in Ru) for monosubstituted allylic alcohols, for their disubstituted counterparts, high catalyst loading and longer reaction times were always required. It is important to note that the catalytic system: i) is active in a large-scale experiment, and ii) could be recycled up to four consecutive runs.

Graphical abstractThe bis-allyl Ru(IV) complex [Ru(η3:η3-C10H16)Cl2(benzimidazole)] is an efficient catalyst for the metal-mediated isomerization of allylic alcohols in their corresponding saturated carbonyl derivatives in the deep eutectic solvent formed by choline chloride and glycerol in a 1:2 ratio (1ChCl/2Gly). It is important to note that this catalytic system involves no presence of any base as co-catalyst. Moreover, the catalyst could be recycled up to four consecutive times in this DES (1ChCl/2Gly) with partial deactivation.Figure optionsDownload full-size imageDownload as PowerPoint slide