Synthesis and asymmetric hydrogenation of (3E)-1-benzyl-3-[(2-oxopyridin-1(2H)-yl)methylidene]piperidine-2,6-dione.

The synthesis of (3E)-1-benzyl-3-[(2-oxopyridin-1(2H)-yl)methylidene]piperidine-2,6-dione 5 from N-benzylglutarimide was achieved in three steps. The asymmetric hydrogenation of 4 gave either the product of partial reduction (10) or full reduction (13), depending on the catalyst which was employed, in high ee in each case. Attempts at asymmetric transfer hydrogenation (ATH) of resulted in formation of a racemic product.

Catalytic hydrogenation of carboxamides and esters by well-defined Cp*Ru complexes bearing a protic amine ligand.

A novel catalytic method for the straightforward hydrogenation of carboxamides and esters to primary alcohols has been developed. Chiral modification in the ligand sphere of the well-defined Cp*Ru catalyst molecule opens up a new possibility for the development of an enantioselective hydrogenation of racemic substrates via dynamic kinetic resolution.

Regioselective lactonization of unsymmetrical 1,4-diols: an efficient access to lactone lignans.

A Cp*Ru-based bifunctional catalyst system (Cp* = η(5)-C(5)(CH(3))(5)) with a suitably-designed PN ligand (PN = chelating tertiary phosphine-protic amine ligand) has been developed for a regioselective lactonization of unsymmetrically substituted 1,4-diols, which may provide an expeditious access to a variety of lactone lignans.

An efficient oxidative lactonization of 1,4-diols catalyzed by Cp*Ru(PN) complexes.

[reaction: see text] An efficient oxidative lactonization of 1,4-diols in acetone is accomplished by the well-defined ruthenium catalyst, whose bifunctional nature underlies the high efficiency as well as unique chemo- and regioselectivity of the reaction which provides a rapid access to gamma-butyrolactones including flavor lactones hinokinin, and muricatacin.