Manganese(I)-Catalyzed Chemoselective Transfer Hydrogenation of the C=C Bond in Conjugated Ketones at Room Temperature.

Chemoselective transfer hydrogenation of C=C bond in α,β-unsaturated ketones is demonstrated at room temperature employing a manganese(I) catalyst and half an equivalent of ammonia-borane (H N-BH ). A series of mixed-donor pincer-ligated Mn(II) complexes, ( PN N )MnX [κ ,κ ,κ -(N-(di-tert-butylphosphaneyl)-6-(1H-pyrazol-1-yl)pyridin-2-amine)MnX ] {X=Cl (Mn2), X=Br (Mn3), X=I (Mn4)} were synthesized and characterized. Amongst the Mn(II) complexes, (Mn2, Mn3, Mn4) and Mn(I) complex, ( PN N )Mn(CO) Br (Mn1) screened; the Mn1 acts as an efficient catalyst for the chemoselective C=C bond reduction in α,β-unsaturated ketones.

Room temperature chemoselective hydrogenation of C[double bond, length as m-dash]C, C[double bond, length as m-dash]O and C[double bond, length as m-dash]N bonds by using a well-defined mixed donor Mn(i) pincer catalyst.

Chemoselective hydrogenation of C[double bond, length as m-dash]C, C[double bond, length as m-dash]O and C[double bond, length as m-dash]N bonds in α,β-unsaturated ketones, aldehydes and imines is accomplished at room temperature (27 °C) using a well-defined Mn(i) catalyst and 5.0 bar H. Amongst the three mixed-donor Mn(i) complexes developed, κ-(PNN)Mn(CO)Br (R = Ph, Pr, Bu); the Bu-substituted complex ( PNN)Mn(CO)Br shows exceptional chemoselective catalytic reduction of unsaturated bonds.