Activation of Mononuclear Arene Ruthenium Complexes for Catalytic Propargylation Directly with Propargyl Alcohols

Abstract

by activation of the propargylic alcohol, leading to the carbonyl ligand formation via allenylidene and alkenyl-hydroxycarbene intermediates. The generation of the catalytically active species requires a short initial thermal activation to induce decoordination of the p-cymene ligand. The in situ generated catalyst has been applied to catalytic transformations of alkynes and propargylic alcohols: propargylation of furans, propargyl ether synthesis from internal and terminal propargylic alcohols with propargyl, homopropargyl and allyl alcohols, selective dimerization of phenylacetylene into E-enyne, and propargyl alcohol rearrangement into a,b-unsaturated aldehydes and ketones via the Meyer-Schuster rearrangement. The propargylation of propargylic alcohols containing internal C C bonds suggests an activation via the Nicholas-type intermediate, the metalstabilized propargyl cation.

Ruthenium(II) half-sandwich complexes containing thioamides: Synthesis, structures and catalytic transfer hydrogenation of ketones

“…Moreover complexes containing phosphine ligands continue to enjoy immense popularity in connection with homogenous catalysis and organometallic chemistry [18e23]. A large number of ruthenium complexes with arene ligands have been employed in different catalytic reactions including allylic alkylation [24], amination [25], cyclization [26], cycloisomerization of dienes [27] and hydroformylation [28] and transfer hydrogenation.…”

Lewis Acid-Catalyzed Propargylic Etherification and Sulfanylation from Alcohols in MeNO2-H2O

“…b) The reactions of cycloalkanols gave a small amount of phenylsulfanylethynylcycloalkenes 5. 46) formed the reaction with other thiols such as 2-thienyl, naphthyl, p-chlorophenyl and cyclohexylthiol and obtained satisfactory results (entries 2-5, Table 4). A variety of propargyl alcohols bearing the substituents such as R 1 ϭ2-thienyl, 1-naphthyl and benzodioxol-5-yl produced some propargyl sulphides 8ba-8gc in moderate to high yields (entries [6][7][8][9][10][11].…”

Ruthenium-Catalyzed Isomerizations of Allylic and Propargylic Alcohols in Aqueous and Organic Media: Applications in Synthesis

“…Because an excess of water is present in the reaction media, complex Q can undergo the Markovnikov addition of water to the coordinated carbon-carbon triple bond to afford the corresponding enones via intermediates R and S. The formation of penyne Q is supported by the fact that if the catalytic process is performed in anhydrous THF, the corresponding free 1,3-enynes can be isolated from the reaction media via demetalation of Q. 51b 52 Thus, using 5 mol% of this complex, the terminal alkynol 1,1-diphenylprop-2-yn-1-ol [i.e., HC≡CC(OH)Ph 2 ] was selectively converted into 3,3-diphenylprop-2-enal (i.e., HCOCH=CPh 2 ) in 89% yield after only 5 minutes in refluxing THF. Remarkably, in contrast to the aforementioned ruthenium-based systems, this precatalyst is also active with internal alkynols and is able to isomerize 1,3-diphenylprop-2-yn-1-ol [i.e., PhC≡CC(OH)HPh] into a mixture of (Z)-and (E)-chalcone (i.e., PhCOCH=CHPh), albeit in moderate yield (49%), after 12 hours.…”