José M. Ezpeleta

A simple and efficient strategy for the preparation of 5-phosphorylated imidazol-2-ones from primary β-enaminophosphonates

Abstract An easy and efficient synthesis of imidazol-2-ones 5 substituted with a phosphonate group in the 5-position is described. The key step is a heterocyclization of functionalized enamines 3. These compounds 3 are formed by addition of primary β-enaminophosphonates 1 to diethyl azodicarboxylate 2.

Structural analysis and magnetic properties of the 1D [Fe(dca)2bipy(H2O)]·1/2H2O and the 3D [Ni(dca)2bipy] (dca = dicyanamide; bipy = 4,4′-bipyridine)

The combined use of bipy (4,4′-bipyridine) and dca (dicyanamide) has led to the preparation of two polymeric compounds of formulae [Fe(dca)2bipy(H2O)]·1/2H2O (1) and [Ni(dca)2bipy] (2). Both have been synthesised and characterised through IR and UV-Vis spectroscopies, thermal analysis, X-ray difracction and measurements of the molar magnetic susceptibility. Compound 1 is 1D and exhibits weak antiferromagnetic interactions. Compound 2 consists of two interpenetrated 3D networks giving rise to weak ferromagnetic interactions. The formation of both types of structure can be related to the different Pearson acidities of FeII and NiII ions.

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.

Synthesis of fluorinated β-aminophosphonates and γ-lactams.

The functionalized polyfluorophosphorylated 1-azadienes I have been prepared by a Wittig reaction of ethyl glyoxalate and perfluorophosphorylated conjugated phosphoranes, obtained by reaction of phosphazenes and fluorinated acetylenic phosphonates. Subsequent reduction of both carbon-carbon and carbon-nitrogen double bonds of these 1-azadienes I affords the fluorine-containing β-aminophosphonates II, with the syn β-aminophosphonate being obtained as the major diastereoisomer. Base-mediated cyclocondensation of a diastereomeric mixture of aminophosphonates II leads exclusively to a new type of functionalized trans-γ-lactams III in a diastereoselective way. A computational study has also been used to explain the observed diastereoselectivity of these reactions.

Cycloaddition Reactions of Neutral 2‐Azadienes with Enamines − Regiospecific Synthesis of Highly Substituted Dihydropyridines and Pyridines

The reaction between electronically neutral 2-azadienes and enamines affords isoquinolines, bicyclic pyridine derivatives, tetrasubstituted 1,2-dihydropyridines, and pyridines. Dimerization of heterodienes gives pentasubstituted 2,3-dihydropyridines and pyridines in a regioselective fashion.

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-β-nitro-phosphonates. Catalytic hydrogenation of (S)-α-amino-β-nitro-phosphonate 2d gives enantiopure (S)-α,β-diaminophosphonate 3.

Regioselective Alkylation Reactions of Enamines Derived from Phosphane Oxides − Synthesis of Phosphorus Substituted Enamino Esters, δ‐Amino‐phosphonates, Pyridone Derivatives and Pyrroles

α-Substituted (2-iminoalkyl)phosphane oxides were obtained from the azaenolates of imines or enamines and alkyl halides. The functionalized imines or enamines thus obtained were used for the synthesis of δ-amino esters, δ-amino phosphonates and heterocycles such as 3,4-dihydropyridin-2-ones, 2-pyridones and pyrroles containing a phosphinyl substituent.

DPDS–DPS in situ transformation at room temperature via a 1,2-nucleophilic addition mechanism

A cleavage–reorganization reaction at room temperature has been detected in three metal organic coordination compounds synthesized from a DPDS [di(4-pyridyl)disulphide] ligand: Mn(NCS)2(DPS)4 (1), [Fe(NCS)2(DPS)2]·2H2O (2) and Zn(NCO)2(DPS) (3), [DPS = di(4-pyridyl)sulphide]. The in situ reorganization process is explained by a 1,2-nucleophilic addition mechanism.

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

In the title compound, [Ni(C24H16N6)2](NCS)2·2H2O, the central NiII ion is octahedrally coordinated by six N atoms of two tridentate 2,3,5,6-tetra-2-pyridylpyrazine ligands (tppz). Two thiocyanate anions act as counter-ions and two water molecules act as solvation agents. O—H⋯N hydrogen bonds are observed in the crystral structure.