(1R,2S)或(1S,2R)-1,2-二苯基-2-氨基乙醇衍生物手性配体的合成及其用于不对称催化反应

重点报道了以（１Ｒ，２Ｓ）或（１Ｓ，２Ｒ）－１，２－二苯基－２－氨基乙醇衍生物手性配体的合成及其用于不对称催化反应的研究，如去氢氨基酸的氢化、醛的乙基锌加成、酮的还原、活泼亚甲基化合物的烷基化、醛的硅腈化和瑞福马斯基反应等．研究了手性配体的结构、底物和反应条件等对上述反应的对映选择性和催化活性的影响．     

A new three‐dimensional neutral framework of lanthanum oxalate: [La2(C2O4)3(DMF)(H2O)3]n

In the title complex, poly[triaquabis(dimethylformamide)di‐μ₃‐oxalato‐μ₂‐oxalato‐dilanthanum(III)], [La₂(C₂O₄)₃(C₃H₇NO)(H₂O)₃]_n, both La ions are coordinated by nine O atoms, forming slightly distorted tricapped trigonal prisms. The two La ions, the terminal water O atom, and the O and N atoms of the dimethylformamide molecule reside on twofold rotation axes, giving the two La‐centered coordination geometries twofold or pseudo‐twofold symmetries. The two oxalate ligands, one of which rests on a center of inversion at the mid‐point of the C—C bond, adopt different bridging modes, connecting with the La ions to form two types of lanthanide oxalate chains, i.e. anionic {[La(C₂O₄)₂(DMF)(H₂O)₂]ⁿ⁻}_n (DMF is dimethylformamide) and cationic zigzag {[La(C₂O₄)(H₂O)]ⁿ⁺}_n, respectively. Each zigzag cationic chain is linked to four adjacent anionic chains via the bridging oxalate anions, and each anionic chain connects with four zigzag cationic chains, constructing a three‐dimensional neutral framework.     

Asymmetric Synthesis XIV: TiCl(Oipr)3-Promoted Asymmetric Coupling Reaction of D-Camphor Ketimine Anion

Optically active 1, 2-Diphenylethylendiamine(9) is obtained by asymmetric oxidative coupling reaction of d-camphor ketimine anion (4). Among various oxidating agents, TiCl(Oipr)₃ is better than l₂, Br₂, CuCl₂, FeCl₃ and BrCH₂CH₂Br.     

The highly chemoselective transfer hydrogenation of the carbon–carbon double bond of conjugated nitroalkenes by a rhodium complex

Chemoselective transfer hydrogenation of conjugated nitroalkenes catalyzed by [RhCl₂Cp¹]₂–diamine complex (Cp¹=η⁵-C₅Me₅) using HCOOH/Et₃N (5:2) (TEAF) as a hydrogen source was realized. A variety of nitrostyrenes, β-methyl nitrostyrenes, and 3-methyl-4-nitro-5-alkenyl-isoxazoles were reduced smoothly in good to excellent yields in short reaction time. Other functional groups are inert under the reaction conditions.     

Facile optical resolution of tert-butanethiosulfinate by molecular complexation with (R)-BINOL and study of chiral discrimination of the diastereomeric complexes

An important synthon, tert-butanethiosulfinate (2), has been effectively resolved by forming molecular complexes with (R)-2,2'-dihydroxy-1,1'-binaphthyl (BINOL, 3) in high enantioselectivity (>99 % ee). The present procedure represents the first example of the resolution of thiosulfinate. The mechanism of chiral discrimination is discussed in terms of molecular recognition based on IR and Xray analyses of the diastereomeric complexes during the resolution. In the less-soluble complex, (R)-3 and (R)-2 self-assembled as a linear supramolecule; however, in the more-soluble complex, (R)-3 and (S)-2 formed a simple bimolecular complex by one stronger hydrogen bond. Hydrogen bonding is the major driving force for effective resolution.     

Synthesis of a water-soluble cationic chiral diamine ligand bearing a diguanidinium and application in asymmetric transfer hydrogenation

A novel water-soluble cationic N-monosulfonated chiral diamine ligand diguanidinium 1c was easily prepared from (R,R)-DPEN and its rhodium complex and was successfully applied in the asymmetric transfer hydrogenation of prochiral ketones and imines in water by using sodium formate and formic acid as co-hydrogen donors. Various substrates were reduced with high yields and good to excellent enantioselectivities (up to >99% ee).     

Chemoselective and enantioselective transfer hydrogenation of β,β-disubstituted nitroalkenes catalyzed by a water-insoluble chiral diamine–rhodium complex in water

Asymmetric transfer hydrogenation of β,β-disubstituted nitroalkenes catalyzed by a chiral diamine–rhodium complex in combination with HCO₂Na–HCO₂H as a hydrogen source in water was successfully realized with high reactivity, excellent chemoselectivity and good enantioselectivity. The metal precursor and pH value of the aqueous solution have a large influence on the reactivity and chemoselectivity. The substituents on the benzene rings and the sulfonyl groups of TsDPEN have significant effects on the enantioselectivity. This catalytic asymmetric transformation is one of the most practical pathways to obtain optically active nitroalkanes.     

ON QUINTIC K-3 SURFACES

If a non-normal quintic surface is birational to a K3 surface,then there are threepossibilities:either it is singular along a conic;or it is singular along two mutuallyintersecting lines;or it is singular along a line and has an isolated triple point outside theline.Conversely if a K3 surface contains a hyperelliptic curve of genus three with anode or simple cusp,then it is birational to a quintic surface of the first type mentionedabove.For the other two cases,the minimal models are also characterized.     

Automorphisms of the Projective Quaternion Unimodular Group of two Dimensions

Let K be the skew field of rational quaternoions.Let R={(a+bi+cj+dk)/2|a,b,c,d =in Z and have the same parity},where Z denotes the ring of rational integers.R is a subring of K and K is the quotient skew field of R. R is usually called the ring of quaternion integers. Let E denote the subgroup of GL_2(R) generated by all elements of the form $[\left( {\begin{array}{*{20}{c}} 1&s\0&1 \end{array}} \right)\]$ and $[\left( {\begin{array}{*{20}{c}} 1&0\t&1 \end{array}} \right)\]$(s,t \in R).Denote the factor groups of GL_2(R) and E modules their centers,both of which are {\pm I},by PGL_2(R) and PE respectively.PE is the commutator subgroup of PGL_2(r). Theorem.Any automorphism of PGL_2(R) (or PE) is one of the following two standard forms $\bar A \mapsto \bar P{\bar A^\sigma }{\bar P^{ - 1}}$ $[A \mapsto \bar P{(\overline {{A^{\tau '}}} )^{ - 1}}{\bar P^{ - 1}}$ where $\bar P \in PGL_2(R)$,\sigma is an automorphism of R and \tau is an anti-automorphism of R.     

Aggregation and columnar assembly of crescent oligoamides

The aggregation and assembly of crescent oligoamides with two to six benzene residues are investigated. In chloroform, the pentamer and hexamer are found to associate into large aggregates. In the solid state, all oligomers examined associate into columnar assemblies via stacking interactions, as shown by X-ray diffraction data from single crystals and powder samples. The columnar assemblies of the pentamer and hexamer should contain hydrophilic channels defined by the constituent oligomers.