Ruthenium Tris(pyrazolyl)borate Complexes. 1. Synthesis and Reactivity of Ru(HB(pz)₃)(COD)X (X = Cl, Br) and Ru(HB(pz)₃)(L₂)Cl (L = Nitrogen and Phosphorus Donor Ligands)

Abstract

The synthesis and catalytic reactivity of a variety of new ruthenium complexes of the tris(pyrazolyl)borate ligand (HB(pz) 3 ) are reported in this paper. From the parent complex Ru(HB(pz) 3 )(COD)X (X ) Cl, Br) the cationic derivatives [Ru(HB(pz) 3 )(COD)L] + (L ) H 2 O, CH 3 CN, pyridine, dmso) have been obtained by treatment with 1 equiv of AgCF 3 SO 3 in CH 2 -Cl 2 solutions of L. Displacement of COD from these latter complexes has been accomplished in boiling dmf solutions of ligands L 2 ) Ph 2 PCH 2 PPh 2 (dppm), Ph 2 PCH 2 CH 2 NMe 2 (pn), and Me 2 NCH 2 CH 2 NMe 2 (tmeda) as well as L ) pyridine and 3-methylpyridine to give Ru(HB-(pz) 3 )(L 2 )Cl and Ru(HB(pz) 3 )(L) 2 Cl, respectively, each in high yield. From some of these complexes, in turn, the chloride ion has been abstracted with either AgCF 3 SO 3 , TlCF 3 SO 3 , or NaBPh 4 in CH 3 CN as the solvent. In this way we obtained [Ru(HB(pz) 3 )(dppm)(CH 3 -CN)]CF 3 SO 3 , [Ru(HB(pz) 3 )(pn)(CH 3 CN)]BPh 4 , and [Ru(HB(pz) 3 )(tmeda)(CH 3 CN)]BPh 4 . Selected X-ray structures are included. Some of the complexes synthesized are efficient catalysts for the formation of selectively C-O-coupled products from the reaction of phenylacetylene with either benzoic acid or allyl alcohols.

Ruthenium‐Catalyzed β‐Alkylation of Secondary Alcohols with Primary Alcohols

“…We have been able to present a clearer picture of the mechanistic aspects of the reaction, and more interestingly, we have demonstrated that the carbonyl complexes resulting from aldehyde decarbonylation, which is usually regarded as the cause of catalyst deactivation, are also active for the alkylation reactions. [14] CpRu-A C H T U N G T R E N N U N G (PPh 3 ) 2 Cl (M2), [15] CpRuA C H T U N G T R E N N U N G (dppm)Cl (M3), [16] TpRuA C H T U N G T R E N N U N G (PPh 3 ) 2 Cl (M4), [17] [18] cis-[Ru(6,6'- [19] and TpRuA C H T U N G T R E N N U N G (PPh 3 )(CO)Ph (M8) [10] were prepared according to literature methods.…”

Metal Vinylidenes and Allenylidenes in Catalysis: Applications in Anti‐Markovnikov Additions to Terminal Alkynes and Alkene Metathesis

“…N,N,N',N'-tetramethylenediamine), have been applied in the addition of benzoic acid to phenylacetylene to produce selectively Z and E enol benzoates. [80] The enynyl ruthenium complex [Ru(Tp)(PhC=C(Ph)C CPh)(PMeiPr 2 )] is remarkably active in the production of unsaturated lactones by endocyclization of a,w-alkynoic acids (Scheme 9). [81] In this reaction the presence of the basic phosphine favors the alkyne to vinylidene tautomerism and allows the formation of macrocyclic enol lactones.…”

“…This is a rare example of the direct formation of a CÀO ether bond. [80] Whereas [RuCl(Cp*)(cod)] (Cp* = C 5 Me 5 ) promotes the oxidative coupling of allyl alcohol with alkynes and alkynols to form g,d-unsaturated aldehydes [85,86] and 5-methylenetetrahydropyrans, [87,88] respectively, the reaction catalyzed by [RuCl(Cp)(PPh 3 ) 2 ]/NH 4 PF 6 promotes the formation of ruthenium vinylidene species and follows a completely different pathway. The expected addition of the hydroxy group to the vinylidene ligand takes place but is followed by a skeleton rearrangement leading to unsaturated ketones.…”

Regio‐ and Stereoselective Intermolecular Hydroalkoxylation of Alkynes Catalysed by Cationic Gold(I) Complexes

“…[1a,2] However, this is not the case for intermolecular hydroalkoxylations. Indeed, although different metals, [3] including palladium, [4,5] platinum, [6] mercury, [7] ruthenium, [8] copper, [9] silver, [10] zinc [11] and gold [12] have been used as catalysts, none of them fulfill the levels of efficiency, mildness and selectivity achieved for the intramolecular version. Therefore, to find selective, efficient and environmentally friendly [13] procedures for the intermolecular hydroalkoxylation of alkynes is of huge interest.…”