The first example of asymmetric hydrogenation of imines with Co2(CO)8/(R)-BINAP as catalytic precursor

Implication of a Silyl Cobalt Dihydride Complex as a Useful Catalyst for the Hydrosilylation of Imines

“…In 1986, Okamoto, a pioneer in this field, and coworkers described the first example of imine hydrogenation using a bis­(dioximato)cobalt quinine complex under mainly stoichiometric conditions . In 2012, Amézquita-Valencia and Cabrera described the use of Co 2 (CO) 8 /( R )-BINAP as a catalytic mixture for the asymmetric reduction of biphenyl ketimines . The same year, Hanson et al described the use of a cobalt complex bearing a bis­[2-(dicyclohexylphosphino)­ethyl]­amine ligand for the hydrogenation of various unsaturated bonds, including three aldimines, but no ketimines were reduced .…”

“…14 In 2012, Ameźquita-Valencia and Cabrera described the use of Co 2 (CO) 8 /(R)-BINAP as a catalytic mixture for the asymmetric reduction of biphenyl ketimines. 15 The same year, Hanson et al described the use of a c obalt complex bearing a bis[2-(dicyclohexylphosphino)ethyl]amine ligand for the hydrogenation of various unsaturated bonds, including three aldimines, but no ketimines were reduced. 16 Finally, in 2014, Von Wangelin et al reported the use of an arene−cobalt complex for hydrogenations, but again, the scope of aldimines is narrow, and no ketimine reduction was reported.…”

Metal-Catalyzed Asymmetric Hydrogenation of C═N Bonds

“…To provide a more sustainable solution, Cabrera and Ameźquita-Valencia introduced the first cobalt catalytic system for the enantioselective hydrogenation of aryl ketimines. 101 They associated the dicobalt octacarbonyl with (R)-BINAP to reduce with excellent yields and moderate to good enantioselectivities a large panel of imines derived from benzophenone (Scheme 72). This reaction occurs under a CO/H 2 gas atmosphere to warrant high yields; it is suggested that the partial CO pressure stabilizes the catalytic species.…”

“…Although great advances have been achieved in the field of Rh-, Ru-, and Ir-catalyzed AIH, the use of poorly abundant and expensive noble metals somehow limits the synthetic utility of this approach, even though in some cases relatively low catalyst loadings are sufficient to complete the reaction. To provide a more sustainable solution, Cabrera and Amézquita-Valencia introduced the first cobalt catalytic system for the enantioselective hydrogenation of aryl ketimines . They associated the dicobalt octacarbonyl with ( R )-BINAP to reduce with excellent yields and moderate to good enantioselectivities a large panel of imines derived from benzophenone (Scheme ).…”

Instituto de Química de la UNAM: catalizando la química con paso firme

“…Con el paso del tiempo, el Dr. Cabrera fue realizando importantes contribuciones a la catálisis en México; cabe destacar su amplia labor en cuanto a procesos catalizados por cobalto, también estudió, entre otras líneas, la isomerización selectiva de epóxidos catalizada por un compuesto de coordinación de estaño de identidad Sn[Co(CO) 4 ] 4 ; [9]. Más tarde, en 2013, el grupo de investigación publicó el primer ejemplo de hidrogenación asimétrica de iminas con un sistema catalítico conformado por el dímero de tetracarbonilo de cobalto en presencia de un ligante quiral como director de la estereoselectividad de la reacción (esquema 1), [10], este tipo de procesos resultan muy atractivos para la química medicinal y la industria farmacéutica. En el mismo terreno, el Dr. Cecilio Álvarez continuó realizando importantes colaboraciones en el área, por caso, en 2005, publicó un trabajo acerca de paladaciclos y su aplicación en la polimerización de etileno [14], en dicha publicación, los autores describieron la síntesis de un nuevo tipo de paladaciclos (2) y estudiaron su actividad catalítica para la síntesis de polietileno.…”