RUTHENIUM TRIS(PYRAZOLYL)BORATE COMPLEXES, PART 11 - FACILE GAMMA-C-HBOND ACTIVATION IN PHOSPHINOAMINE LIGANDS RESULTING IN REGIOSELECTIVEAND STEREOSELECTIVE C-C COUPLING WITH TERMINAL ACETYLENES

Tris(pyrazolyl)borate ruthenium complexes that contain the phosphinoam ine ligands Ph2PCH2CH2NMe2, Ph2PCH2CH2NEt2, and Ph2PCH2CH2-NiPr2 react with terminal acetylenes HC=CR (R = Ph, COOEt, Ch(2)Ph, ferrocenyl, C 6H9, nBu) to yield the novel coupling products [Ru(tp)(Cl)(kappa(3)(P, C, C)-Ph2PCH=CHC(R)=CH2)], [Ru(tp)(Cl)(kappa(3)(P, C, C)-Ph2PCH2CH(NE t2)CH=CHR)], [Ru(tp)(Cl)(kappa(3)(P, C, C)Ph2PCH2CH(NiPr2)CH=CHR)], [R u(tp)(Cl)(kappa(3)(P, C, C)-Ph2PCH2CH(NEt2)C(R)=CH2)], and [Ru(tp)(Cl) (kappa(3)(P, C, C)-Ph2PCH2CH(NiPr2)C(R)=CH2)]. The C-C couplings invol ved take place regioselectively at the gamma-carbon atom of the phosph inoamine ligand and, depending on the steric requirements of R, either at the internal or terminal carbon atom of the acetylene molecule. Al l these reactions proceed in a highly diastereoselective fashion. With Ph2PCH2CH2NMe, as the ligand, the C-C coupling involves C-N bond clea vage and elimination of HNMe2 leading to dehydrogenation of the -CH2CH 2-chain.