871576-73-7Relevant academic research and scientific papers
Reduction and C(sp2)-H bond activation of ketones promoted by a cyclopentadienyl-osmium-dihydride-dihydrogen complex
Esteruelas, Miguel A.,Hernandez, Yohar A.,Lopez, Ana M.,Olivan, Montserrat,Onate, Enrique
, p. 5989 - 6000 (2005)
The dihydride-dihydrogen complex [OsH2(η5-C 5H5)(η2-H2)(PiPr 3)]BF4 (2) has been prepared by addition of HBF 4·OEt2 to OsH3H3(η 5-C5H5)(PiPr3) (1), and its reactions with benzylideneacetone, methyl vinyl ketone, acetophenone, and benzylideneacetophenone have been studied. The reaction with benzylideneacetone leads initially to [OsH2(η5-C5H 5){κ1-OC(CH3)CH=CHPh}-(P iPr3)]BF4 (3), which in dichloromethane is converted to the hydroxyallyl derivative [OsH-(η5-C 5H5){η3-CH2C(OH)CHCH 2Ph}(PiPr3)]BF4 (4). Complex 4 releases 4-phenylbutan-2-one, and the resulting metallic fragment activates a Cβ(sp2)-H bond of a new molecule of benzylideneacetone to give [OsH(η5-C5H 5){C(Ph)CHC(O)CH3}(PiPr3)]BF 4 (5), which affords Os(η5-C5H 5){C(Ph)CHC(O)CH3}(PiPr3) (6) by deprotonation with NaOCH3. The reaction of 2 with methyl vinyl ketone gives ethyl methyl ketone and [OsH(η5-C5H 5){CHCHC(O)-CH3}(PiPr3)]BF 4 (9). The latter can also be obtained from Os(η5- C5H5)Cl{η2-CH2=CHC(O)-CH 3(PiPr3) (7) via the intermediate [Os(η5-C5H5){CH2CHC(O)CH 3}(PiPr3)]BF4 (8). Treatment of 9 with NaOCH3 leads to an equilibrium mixture of Os(η5- C5H5){CHCHC(O)CH3}-(PiPr 3) (10) and the hydride-vinylidene OsH(η5-C 5H5){=C=CHC(O)CH3}(PiPr3) (11). The reaction of 2 with acetophenone gives 1-phenylethanol and the orthometalated derivative [OsH(η5-C5H5){C 6H4C(O)CH3}(PiPr3)] BF4 (13), which is deprotonated with NaOCH3 to give Os(η5-C5H5){C6H 4C(O)CH3 (14), while the reaction of 2 with benzylideneacetophenone leads to [OsH(η5-C5H 5){C(Ph)CHC(O)Ph}(PiPr3)]BF4 (15), which yields Os(η5-C5H5){C(Ph)CHC(O)Ph} (PiPr3) (16) by deprotonation. Complexes 3, 10, and 13 have been characterized by X-ray diffraction analysis.
