Design and characterization of Fe(II) complexes with tetradentate ligands exhibiting spin-crossover near room temperature.

Construction of spin-crossover (SCO) materials is very appealing for applications such as molecular switches and information storage. This study focuses on the design of Fe(II) complexes using ,'-bis(2-pyridinylmethyl)-1,2-ethanediamine-based ligands with an N4 structure for SCO material development. By incorporating -substituted benzene groups into the ligand's pyridine moiety, two polymorphs, α and β, were obtained, both exhibiting SCO activity.

Nickel-Catalyzed Desymmetric Reductive Cyclization/Coupling of 1,6-Dienes: An Enantioselective Approach to Chiral Tertiary Alcohol.

We have developed a nickel-catalyzed desymmetric reductive cyclization/coupling of 1,6-dienes. The reaction provides an efficient method for constructing a chiral tertiary alcohol and a quaternary stereocenter by a single operation. The method has excellent diastereoselectivity and high enantioselectivity, a broad substrate scope, as well as good tolerance of functional groups.

Chiral Dirhodium Tetraphosphate-Catalyzed Enantioselective Si-H Bond Insertion of α-Aryldiazoacetates.

A highly enantioselective Si-H bond insertion reaction of α-aryldiazoacetates catalyzed by chiral spiro dirhodium tetraphosphate was developed. Various chiral α-silyl esters were prepared with high yield (up to 92%) and excellent enantioselectivity (up to >99% ee) through this protocol. It is noteworthy that the 2-substituted aryl diazoacetates, which are challenging substrates for other chiral dirhodium catalysts, also exhibited good results in this reaction.

Nickel-Catalyzed Desymmetrizing Cyclization of 1,6-Dienes to Construct Quaternary Stereocenters.

A highly enantioselective and diastereoselective nickel-catalyzed desymmetrizing cyclization of 1,6-dienes was developed by using chiral spiro phosphoramidite ligands. The reaction provides a new atom- and step-economical approach to chiral spiro lactones and analogues bearing a quaternary stereocenter.