668-45-1Relevant articles and documents
Half-Sandwich Guanidinate-Osmium(II) Complexes: Synthesis and Application in the Selective Dehydration of Aldoximes
Francos, Javier,González-Liste, Pedro J.,Menéndez-Rodríguez, Lucía,Crochet, Pascale,Cadierno, Victorio,Borge, Javier,Anti?olo, Antonio,Fernández-Galán, Rafael,Carrillo-Hermosilla, Fernando
, p. 393 - 402 (2016/02/03)
The novel guanidinate-osmium(II) complexes [OsCl{κ2-(N,N′)-C(NR)(NiPr)NHiPr}(η6-p-cymene)] [R = Ph (3a), 4-C6H4F (3b), 4-C6H4Cl (3c), 4-C6H4CF3 (3d), 3-C6H4CF3 (3e), 3,5-C6H3(CF3)2 (3f), 4-C6H4CN (3g), 4-C6H4Me (3h), 3-C6H4Me (3i), 2-C6H4Me (3j), 4-C6H4tBu (3k), 2,6-C6H3iPr2 (3l), 2,4,6-C6H2Me3 (3m)] have been synthesized in high yields (70-88 %) by treatment of THF solutions of the dimeric precursor [{OsCl(μ-Cl)(η6-p-cymene)}2] (1) with 4 equivalents of the corresponding guanidine (iPrHN)2C=NR (2a-m) at room temperature. The easily separable guanidinium chloride salts [(iPrHN)2C(NHR)]Cl (4a-m) were also formed in these reactions. The structures of 3a, 3d, and 3h were unequivocally confirmed by X-ray diffraction methods. Complexes 3a-m proved to be active in the catalytic dehydration of aldoximes. The best results were obtained with [OsCl{κ2-(N,N′)-C(N-4-C6H4CF3)(NiPr)NHiPr}(η6-p-cymene)] (3d; 5 mol-%), which, in acetonitrile at 80C, was able to convert selectively a large variety of aromatic, heteroaromatic, α,β-unsaturated, and aliphatic aldoximes into the corresponding nitriles in high yields and short reaction times. Novel osmium(II)-guanidinate complexes of general composition [OsCl{κ2-(N,N′)-C(NR)(NiPr)NHiPr}(η6-p-cymene)] (R = Ar) have been synthesized and successfully employed as catalysts for the selective conversion of aldoximes into nitriles.
Cyclic aromatic analogues of the hendrickson reagent; NMR studies and electrophilic properties
Moussa, Ziad
experimental part, p. 460 - 468 (2012/03/11)
Two novel cyclic aromatic analogues of the Hendrickson POP reagent, 1,1,3,3-tetraphenyl-1,3-dihydro-2,1,3-benzoxadiphosphole-1,3-diium bis(trifluoromethanesulfinate) and bis(trifluoromethanesulfonate), have been readily prepared by the treatment of 1,2-bis(diphenylphosphino)benzene or 1,2-bis(diphenylphosphoryl)benzene, respectively, with trifluoromethanesulfonic anhydride in dichloromethane. 31P and 19F NMR studies indicated that while the latter complex is formed as the sole product, the former species was shown to be the predominant component in equilibrium with 1-(diphenylphosphino)-2-[diphenyl(trifluoromethylsulfonyloxy)phosphonio]benzene trifluoromethanesulfinate and 1,2-bis[diphenyl(trifluoromethylsulfonyloxy) phosphonio]benzene bis(trifluoromethanesulfinate). The dehydrating POP systems were exploited in the conversion of aldoximes into nitriles. The dehydration occurred rapidly at room temperature and produced high yields with a variety of alkyl- and arylaldoximes, tolerating a wide range of substrates and functional groups. Georg Thieme Verlag Stuttgart New York.
NMR Studies and electrophilic properties of triphenylphosphine-trifluoromethanesulfonic anhydride; a remarkable dehydrating reagent system for the conversion of aldoximes into nitriles
Moussa, Ziad,Ahmed, Saleh A.,ElDouhaibi, Ahmad S.,Al-Raqa, Shaya Y.
experimental part, p. 1826 - 1831 (2010/09/07)
NMR Studies on the reaction of triphenylphosphine with various amounts of triflic anhydride at 0 °C is described. The reagent structure resulting from mixing 1.3 equiv of Ph3P with Tf2O (1.0 mmol) has been established as an equilibrium mixture consisting mainly of triphenyl(trifluoromethylsulfonyloxy)phosphonium trifluoromethanesulfinate and the corresponding bis(triphenyl)oxodiphosphonium trifluoromethanesulfinate dimer. The electrophilic properties of the system have been exploited in the development of a mild method for converting aldoximes into nitriles. The dehydration occurs at 0 °C under very mild conditions by initial activation of the oxime oxygen, followed by treatment with a base and subsequent elimination of triphenylphosphine oxide. The substrate scope and functional group tolerance of this useful method are explored.