Synthesis and Reactivity of [Ru(Cp*)(L)(MeCN)2][PF6] (L = Ph2POMe or Ph2P‐o‐tolyl) and {Ru(Cp*)[Ph2PCH2C(tBu)=O](MeCN)}[PF6] Complexes, Their Involvement as Catalyst Precursors for Regioselective Allylic Substitution Reactions and Related [Ru(Cp*)Cl(Ph2POMe)(RCHCHCH2)][PF6] η3‐Allyl Ruthenium(IV) Intermediates

Abstract

AbstractThe synthesis of the new complexes [Ru(Cp*)(L)(MeCN)2][PF6] (L = Ph2POMe or Ph2P‐o‐tolyl) and {Ru(Cp*)[Ph2PCH2C(tBu)=O](MeCN)}[PF6] (2a–c) is achieved starting from [Ru(Cp*)(MeCN)3][PF6]. The acetonitrile ligands in complexes 2a–c are labile, as emphasised by the easy formation of {Ru(Cp*)(CO)2[Ph2PCH2C(=O)tBu]}[PF6] (3). The keto‐phosphane is used as a tool to convert 3 into {Ru(Cp*)(CO)[Ph2PCH2C(tBu)=O]}[PF6] (5). Complex 5 reacts with 1,1‐diphenyl‐2‐propyn‐1‐ol in methanol as solvent toafford the vinyl‐carbene complex {Ru(Cp*)(CO)[=C(OMe)CH=CPh2][Ph2PCH2C(=O)tBu]}[PF6]. The new η3‐allyl ruthenium(IV) derivatives [Ru(Cp*)Cl(Ph2POMe)(CH2CMeCH2)][PF6] and [Ru(Cp*)Cl(Ph2POMe)(RCHCHCH2)][PF6] (R = Me; nPr, 8d; or Ph, 8e) are obtained by reacting 2a with the appropriate allylic halide. The X‐ray crystal structure determination of the compounds 8d and 8e disclosed an endo‐trans‐RCHCHCH2 η3‐allyl ligand. The formation of branched allyl aryl ethers is regioselectively favoured when complexes 2a–c are involved as catalyst precursors for the etherification of cinnamyl chloride, chlorohexene and 3‐chloro‐4‐phenylbut‐1‐ene with phenol, p‐methoxyphenol, cresols and (o or p)‐chlorophenols, in the presence of K2CO3. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)