Chiral diols are an integral part of chiral building blocks and synthetic intermediates. Transition metal-catalyzed asymmetric hydrogenation and transfer hydrogenation of diketones are recognized as one of the most straightforward and efficient methods for the preparation of enantiomerically enriched diols. Meanwhile, the mono-reduction product of diketones, chiral hydroxyketones, has wide application in chiral fragment construction as well, among which, desymmetrization of cyclic diketones possesses the capability of establishing multiple chiral centers in one step. In this paper, research progress of asymmetric hydrogenation and transfer hydrogenation of diketone compounds in recent decades is reviewed from the perspective of different substrate types (1,2-/1,3-/1,4-diketones), with emphasis on the influence of coordination mode between substrate and catalyst species on the stereoselectivity. In addition, future challenges and development tendencies in this field are summarized and prospected.
With the increasing demand for homoallylic silanes and allylic silanes,
the highly efficient and regioselective hydrosilylations of conjugated
dienes are urgently needed. Herein, we developed a Ni-catalyzed
regiodivergent hydrosilylation of aromatic conjugated dienes by
adjusting the temperature and ligands. Under low temperature (-30 oC),
an eternal-ligand-free system (Ni/t-BuOK) can efficiently facili-tate
the 3,4-anti-Markovnikov hydrosilylation to provide homoallylic silanes
via electrophilic activation process; under room temperature (25 oC), a
ligand-controlled system (Ni/t-BuOK/PPh3) can eventuate the
3,4-Markovnikov hydrosilylation to produce allylic silanes via
Chalk-Harrod process. Both systems are compatible with various
conjugated dienes and primary silanes in excellent yields and
regioselec-tivities.
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