Synthesis and molecular structure of [RuCl{C(=CHPh)OC(=O)CH2CH3}(CO)(PPh3)(2)]: a real intermediate in ruthenium complex-catalyzed selective synthesis of a (Z)-enol ester

Reaction of [RuCl(eta(2)-O2CCH2CH3)(CO)(PPh3)(2)] (1) and phenylacetylene g ives [RuCl{C(=CHPh)OC(=O)CH2CH3}(CO)(PPh3)(2)] (2a). The X-ray structure an alysis of 2a reveals that it includes a (Z)-enol ester-like 1-propanoyloxy- 2-phenylethenyl-C-1,O ligand. In the catalytic addition of propanoic acid t o phenylacetylene, the complex 2a acts as a real intermediate that gives (Z )-2-phenylethenyl propanoate, selectively. The presence of the free PPh3 in the reaction mixture depresses formation of some dicarbonylruthenium speci es that catalytically produce (E)- and Markovnikov-type enol esters. (C) 20 00 Elsevier Science S.A. All rights reserved.