Synthesis of enol esters catalysed by ‘early–late’ Ti–Ru complexes

The titane–ruthenium heterobimetallic compounds (p-cymene)[(η5-C5H5)(μ-η5:η1-C5H4(CH2)mPR2)TiCl2]RuCl24–6 have been revealed to be quite good catalysts for the addition of formic acid to 1-hexyne and phenylacetylene. These preliminary results led us to synthesize new tetrametallic complexes 10–12 via the reaction of the titanocene phosphanes 1–3 with the polymer [Ru(CO)2(μ-O2CH)]n. Their catalytic ability for the enol esters formation has been studied.