Ruthenium-mediated cyclometalation reactions of allene and allylphosphine C=C Bonds: Synthesis of j(p),η4-(hexa-2,5-dien-1-yl) diphenylphosphine-ruthenium(ii) complexes

Article abstract of DOI:10.1021/om200668h

The cyclopentadienyl-containing complex [Ru(η⁵-C ₅H₅)(MeCN){k³- (P,C,C)-Ph₂PCH ₂CH=CH2}][PF₆] (1) reacts with allenes, giving regioselectively the η₂-allene complexes [Ru(η⁵- C₅H₅)(MeCN){k(P)-Ph₂PCH₂CHdCH ₂}(η²- CH₂=C=CR¹R ²)][PF₆] [R¹ = R²=Me (3); R ¹ = H, R² = Ph (4); R¹R² =-(CH ₂)₅- (5)]. On the other hand, the reaction of the pentamethylcyclopentadienyl-containing complex [Ru(η⁵-C ₅Me₅)(MeCN){k³(P,C,C)-Ph₂PCH ₂CHdCH₂}][OTf] (2) with allenes yields regio- and stereoselectively the complexes [Ru(η⁵-C₅Me ₅){k(P),η⁴- Ph₂PCH₂CHdCHC(R ¹R²)CHdCH₂}][OTf] [R¹ = R ² = Me (6); R¹ = H. R² = Ph (7); R ¹R² = -(CH₂)₅- (8)] via the intermolecular coupling of allene and allyldiphenylphosphine ligands. The intermediate complex [Ru(η⁵-C₅Me₅)(MeCN) {k(P)- Ph₂PCH₂CHdCH₂}{η²-CH ₂=C=CMe₂}][OTf] (9) has been spectroscopically characterized. The structure of complex [Ru(η⁵-C ₅Me₅){k(P),η⁴-Ph₂PCH ₂CHdCHC- (Me)₂CHdCH₂}][{3,5-(CF ₃)₂C₆H₃}₄B] (6a) has been resolved by X-ray diffraction analysis.