Triruthenium Dodecacarbonyl

Typical procedure (R = Ph): Diphenylacetylene (89 mg), Ru₃(CO)₁₂ (9.6 mg), PPh₃ (6.6 mg), Acetic acid (46 mg), H₂O (18 mg) and DMF (1 mL) are placed in a 25 mL thick-walled tube under a flow of nitrogen. The tube is heated at 145 °C with stirring for 24 h. The reaction mixture is cooled to rt and is purified by silica gel column chromatography (eluent: cyclohexane) to give (Z)-stilbene (84 mg, 93 %) with the selectivity of 96 % (GC). When TFA (85.5 mg) is employed, the reaction is carried out using Ru₃(CO)₁₂ (3.2 mg) at 145 °C for 3 h, and the reaction mixture is worked up as above to give (E)-stilbene (81.8 mg, 91 %) with the selectivity of >99 % (GC).