Asymmetric Synthesis of Functionalized Tetrasubstituted α-Aminophosphonates through Enantioselective Aza-Henry Reaction of Phosphorylated Ketimines.

Bifunctional Cinchona alkaloid thioureas efficiently catalyze asymmetric nucleophilic addition of nitromethane to ketimines derived from α-aminophosphonic acids to afford tetrasubstituted α-amino-ß-nitro-phosphonates. Catalytic hydrogenation of (S)-α-amino-ß-nitro-phosphonate 2d gives enantiopure (S)-α,ß-diaminophosphonate 3.

Bis(2,3,5,6-tetra-2-pyridyl-pyrazine-κN,N,N)nickel(II) dithio-cyanate dihydrate.

In the title compound, [Ni(C(24)H(16)N(6))(2)](NCS)(2)·2H(2)O, the central Ni(II) ion is octahedrally coordinated by six N atoms of two tridentate 2,3,5,6-tetra-2-pyridyl-pyrazine ligands (tppz). Two thio-cyanate anions act as counter-ions and two water mol-ecules act as solvation agents. O-H⋯N hydrogen bonds are observed in the crystral structure.

Reactions of conjugate phosphinyl- and phosphonyl-nitroso alkenes with enamines. Preparation of N-hydroxypyrrole derivatives.

The synthesis of highly functionalized N-hydroxypyrrole derivatives by the formal [3+2] cycloaddition reaction of enamines and nitroso alkenes derived from phosphine oxides and phosphonates is reported. Intermediate phosphorylated nitrones, whose formation can be explained by a conjugate addition of enamines to phosphorylated nitroso alkenes and formation of the five-membered heterocycles, are isolated.