tris(pentafluorophenyl)-borane in toluene under Ar, -78°C, 3 h;

bis(triphenylphosphine)carbonylrhodium(I) chloride in not given the catalyst ( 1 mol percent ) should be mixed with Bu3SnH before addn. of acetylene ( 5 - 10 percent excess ), 0 ° C, 0.5 h, under nitrogen, the consumption of Bu3SnH was monitored by GLC; short pass distillation, GC;