Catalytic use of layered materials for fine chemical syntheses

The present work reviews the catalytic use of layered solid materials for fine chemical syntheses with focus on layered double hydroxides, but including other classes of layered compounds of catalytic relevance.

Novel chiral Schiff base/Ti(iv) catalysts for the catalytic asymmetric epoxidation of N-alkenyl sulfonamides

A novel highly enantioselective Schiff base/Ti(iv) catalyst for the catalytic asymmetric epoxidation of a series of N-alkenyl sulfonamides under mild conditions was described.

Molecular and polymeric zinc(II) phosphonates: isolation of an octanuclear ellipsoidal ensemble

The reaction of zinc(II) perchlorate with trichloromethyl phosphonic acid at room temperature afforded, upon crystallization, a two-dimensional layered coordination polymer possessing a dinuclear repeat unit, [{Zn2(Cl3CPO3)2(H2O)3}·1.5H2O]n (1). Modification of the above reaction by involving a co-ligand afforded the tetranuclear complex, [{Zn4(η(1)-DMPzH)6(Cl3C-PO3)2}(μ-OH)2(ClO4)2] (2). The molecular structure of 2 reveals that the tetranuclear core is non-planar and consists of three contiguous inorganic rings which include one 8-membered Zn2P2O4 ring and two six-membered Zn2PO3 rings. Replacement of Zn(ClO4)2·6H2O with ZnCl2 under the same reaction conditions that afforded 2 allowed the formation of the dinuclear complex [{(ZnCl)2(η(2)-Pz)2(Cl3CPO3)}(Et3NH)2] (3). 3 possesses a bicyclic core containing a seven-membered Zn2N2O2P ring. In 3, the phosphoryl oxygen atom (P=O) is involved in a bifurcated hydrogen bonding interaction with the triethylammonium cation. The reaction of ZnCl2 and 2,3,5,6-(Me)4C6HCH2PO3H2 afforded the octanuclear complex [Zn8(Cl)6{2,3,5,6-(Me)4C6HCH2PO3}6(Et3N)2](Et3NH)2]·2n-hexane·3H2O (4). The core of 4 is ellipsoid-shaped with the end-end polar distance (C-C) being ~20 Å.

Polymer-immobilized chiral catalysts

This review illustrates the current strategies and potential of polymer-immobilized chiral catalysts for highly enantioselective asymmetric synthesis.

Di-, tri- and tetranuclear molecular vanadium phosphonates: a chloride encapsulated tetranuclear bowl

Synthesis and characterization of three dinuclear, two dinuclear and one tetranuclear vanadium phosphonates is being reported. These include a chloride encapsulated tetranuclear bowl-shaped complex.