174757-35-8Relevant articles and documents
Arene-Ruthenium Complexes of 1,1′-Bis(ortho-carborane): Synthesis, Characterization, and Catalysis
Chan, Antony P. Y.,Jeans, Rebekah J.,Riley, Laura E.,Rosair, Georgina M.,Sivaev, Igor B.,Taylor, James,Welch, Alan J.
supporting information, (2019/09/06)
Deprotonation of 1,1′-bis(ortho-carborane) with nBuLi in THF followed by reaction with [RuCl2(p-cymene)]2 affords, in addition to the known compound [Ru(κ3-2,2′,3′-{1-(1′-closo-1′,2′-C2B10H10)-closo-1,2-C2B10H10)}(p-cymene)] (I), a small amount of a new species, [Ru(κ3-2,2′,11′-{1-(7′-nido-7′,8′-C2B9H11)-closo-1,2-C2B10H10)}(p-cymene)] (1a), with two B-agostic B-H?Ru bonds, making the bis(carborane) unit a closo-nido-X(C)L2 ligand, a previously unreported bonding mode. Similar species were also formed with arene = benzene (1b), mesitylene (1c), and hexamethylbenzene (1d), although in the last two cases the metallacarborane-carborane species [1-(1′-closo-1′,2′-C2B10H11)-3-(arene)-closo-3,1,2-RuC2B9H10)], 2c and 2d, were also isolated. With the bis(ortho-carborane) transfer reagent [Mg(κ2-2,2′-{1-(1′-closo-1′,2′-C2B10H10)-closo-1,2-C2B10H10)}(DME)2], the target compounds [Ru(κ3-2,2′,3′-{1-(1′-closo-1′,2′-C2B10H10)-closo-1,2-C2B10H10)}(arene)], 4b and 4d, were prepared in reasonable-to-good yields, although for arene = benzene and mesitylene small amounts of the unique paramagnetic species [{Ru(arene)}2(μ-Cl)(μ-κ4-2,2′,3,3′-{1-(1′-closo-1′,2′-C2B10H9)-closo-1,2-C2B10H9})], 3b and 3c, were also formed. In compounds 3, the bis(carborane) acts as a closo-closo-X4(C,C′,B,B′) ligand to the Ru2 unit. In I, 4b, and 4d, the B-agostic B-H?Ru bond is readily cleaved by MeCN, affording compounds [Ru(κ2-2,2′-{1-(1′-closo-1′,2′-C2B10H10)-closo-1,2-C2B10H10})(arene)(NCMe)] (5a, 5b, and 5d) and suggesting that I, 4b, and 4d could act as Lewis acid catalysts, which is subsequently shown to be the case for the Diels-Alder cycloaddition reactions between cyclopentadiene and methacrolein, ethylacrolein and E-crotonaldehyde. All new species were characterized by multinuclear NMR spectroscopy and 1a, 1c, 1d, 2c, 2d, 3b, 3c, 4b, 4d, 5a, 5b, and 5d were also characterized crystallographically.
Remote Tris(pentafluorophenyl)borane-Assisted Chiral Phosphoric Acid Catalysts for the Enantioselective Diels-Alder Reaction
Hatano, Manabu,Ishihara, Hideyuki,Goto, Yuta,Ishihara, Kazuaki
, p. 564 - 570 (2016/03/12)
Tris(pentafluorophenyl)borane-assisted chiral supramolecular phosphoric acid catalysts were developed for the model Diels-Alder reaction of α-substituted acroleins with cyclopentadiene. Two remotely coordinated tris(pentafluorophenyl)boranes should help to increase the Bronsted acidity of the active center in the supramolecular catalyst and create effective bulkiness for the chiral cavity. The prepared supramolecular catalysts acted as not only conjugated Bronsted acid-Bronsted base catalysts but also bifunctional Lewis acid-Bronsted base catalysts with the addition of a central achiral Lewis acid source such as catecholborane.
Asymmetric Diels–Alder Reaction of α-Substituted and β,β-Disubstituted α,β-Enals via Diarylprolinol Silyl Ether for the Construction of All-Carbon Quaternary Stereocenters
Hayashi, Yujiro,Bondzic, Bojan P.,Yamazaki, Tatsuya,Gupta, Yogesh,Ogasawara, Shin,Taniguchi, Tohru,Monde, Kenji
supporting information, p. 15874 - 15880 (2016/10/25)
The asymmetric Diels–Alder reaction of α-substituted acrolein proceeds in the presence of the trifluoroacetic acid salt of trifluoromethyl-substituted diarylprolinol silyl ether to afford the exo-isomer with both excellent diastereoselectivity and high en
