Ádám Tajti

Microwave-assisted synthesis of (aminomethylene)bisphosphine oxides and (aminomethylene)bisphosphonates by a three-component condensation

Summary A practical method was elaborated for the synthesis of (aminomethylene)bisphosphine oxides comprising the catalyst- and solvent-free microwave-assisted three-component condensation of primary amines, triethyl orthoformate and two equivalents of diphenylphosphine oxide. The method is also suitable for the preparation of (aminomethylene)bisphosphonates using (MeO)2P(O)H/(MeO)3CH or (EtO)2P(O)H/(EtO)3CH reactant pairs and even secondary amines. Several intermediates referring to the reaction mechanism together with a few by-products could also be identified.

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N–H···O=P intermolecular hydrogen bridges pair.

Microwave-Assisted Synthesis of Organophosphorus Compounds

Abstract Kabachnik-Fields reactions of a variety of amines, phospha-Michael additions to maleimide derivatives and alcoholysis of dialkyl phosphites were studied under microwave conditions. GRAPHICAL ABSTRACT

Microwave-assisted alcoholysis of dialkyl phosphites by ethylene glycol and ethanolamine

Abstract A study on the microwave-assisted alcoholysis of diethyl phosphite with ethylene glycol revealed that after optimization of the conditions (molar ratio, temperature and time), the target “monomer,” (HOCH2CH2O)2P(O)H was formed in a proportion of 59 %, but with an incomplete conversion. The formation of the (HOCH2CH2O)(EtO)P(O)H and H(EtO)(O)POCH2CH2OP(O)(OEt)H by-products was, in most cases, inevitable. The alcoholysis with ethanolamine was more efficient and took place in a conversion of 100 % to afford H2NCH2CH2O)2P(O)H in a proportion of 85 %. An alkyl substituent on the N-atom prevented the alcoholysis.

Esterification of benzoic acid in a continuous flow microwave reactor

AbstractThe direct esterification of benzoic acid with a series of aliphatic alcohols was performed in a continuous flow microwave (MW) reactor. In the first stage, the reactivity of the alcohols towards benzoic acid was mapped in a batch MW reactor. Then, the different esterifications were optimized in the continuous reactor. All parameters including the temperature could be controlled. Graphical abstractᅟ

Microwave-assisted alcoholysis of dialkyl H-phosphonates by diols and amino alcohols

GRAPHICAL ABSTRACT ABSTRACT The microwave-assisted alcoholysis of dialkyl H-phosphonates with diols and amino alcohols aiming at P-functionalized monomers was studied. Depending on the conditions (molar ratio, temperature, time), the reaction could be fine-tuned to afford the target mono and bis hydroxyalkyl or aminoalkyl H-phopshonate derivatives. The formation of three types of by-products was also investigated. Thermal accomplishments showed lower efficiency in the transesterifications.

Formation of compounds with P–C–N moiety by microwave-assisted condensations

GRAPHICAL ABSTRACT ABSTRACT Organophosphorus compounds containing the P-C-N moiety have been synthesized by microwave-assisted condensations. The synthesis of chiral α-aminophosphonate and α-aminophosphinate derivatives was studied using etyl octyl phosphite or alkyl phenyl-H-phosphinates. Amino-methylenebisphosphonates and amino-methylenebisphosphine oxides were also prepared by the three-component condensation of an amine, an orthoformate and the appropriate >P(O)H reagent.

Continuous Flow Alcoholysis of Dialkyl H-Phosphonates with Aliphatic Alcohols

The continuous flow alcoholysis of dialkyl H-phosphonates by aliphatic alcohols in the absence of a catalyst was elaborated using a microwave (MW) reactor equipped with a flow cell. By the precise control of the reaction conditions, the synthesis could be fine-tuned towards dialkyl H-phosphonates with two different and with two identical alkyl groups. In contrast to the “traditional” batch alcoholysis, flow approaches required shorter reaction times, and the products became available at a larger scale.

Synthesis of platinum, palladium and rhodium complexes of α aminophosphine ligands

α-Aminophosphine-type ligands are of interest as building blocks of transition metal complexes. This review focuses on the utilization of α-aminophosphines as monodentate and bidentate ligands in platinum, palladium and rhodium complexes. Besides the linear derivatives, the applications of cyclic α-aminophosphines as ligands are also summarized. Various aspects, such as synthesis, structure and applications, as well as the catalytic activity of these complexes are discussed.

NMR and symmetry in bisphosphonates R1R2N-CH[P(O)(OMe)2]2

GRAPHICAL ABSTRACT ABSTRACT (Amino-methylene)bisphosphonates R1R2N-CH[P(O)(OMe)2]2 bearing achiral and chiral substituents (R1 = Ph, R2 = H, Me; and R1 = PhCH(Me), R2 = Me, Bn) were synthesized and characterized in CDCl3 by 1H, 1H{31P}, 13C{1H}, 31P{1H}, and 31P NMR spectra. [P(O)(OMe)2]2 fragments from achiral compounds give rise to complex 1H NMR spectra characteristic for the [A3M3X]2 1H NMR spectra while chiral compounds yield A3G3M3T3XY type spectra. Aspects of molecular symmetry governing the multiplet patterns are discussed and precise spectral parameters are calculated by line-shape iterations.