One pot conversion of acetyl chloride to dehydroacetic acid and its coordination in a ruthenium(II) arene complex

The reaction of [(η6-p-cymene)RuCl(κ2N,O- l- serinate)], 1, with CH3C(O)Cl/NEt3, in chloroform at reflux temperature, led to the serendipitous isolation of the dehydroacetate complex [(η6-p-cymene)RuCl(κ2O,O′-dha)], 2, in low amount. Then, dehydroacetic acid (dhaH) was prepared in one pot by self condensation of acetyl chloride in the presence of NEt3 at room temperature, this reaction being unusual in the landscape of the chemistry of acyl chlorides. Complex 2 was synthesized in 89% yield from [(η6-p-cymene)RuCl2]2 and dhaH, and fully characterized by means of X-ray diffraction, IR and NMR spectroscopy. Complex 2 underwent fast and extensive dissociation of the dehydroacetate ligand in dmso/water solution, the degree of dissociation being substantially higher than that observed for the acetylacetonate ligand from [(η6-p-cymene)RuCl(κ2O,O′-acac)], 3.