The Synthesis of N,N‐Bis(dialkoxyphosphinoylmethyl)‐ and N,N‐Bis(diphenylphosphinoylmethyl)glycine Esters by the Microwave‐Assisted Double Kabachnik–Fields Reaction

Abstract

The condensation of a glycine ester, two equivalents of paraformaldehyde, and the same quantity of a dialkyl phosphite or diphenylphosphine oxide afforded the title compounds as new bis(phospha‐Mannich) products under microwave (MW) conditions at 100°C. The dialkoxyphosphinoylmethyl derivatives were synthesized under solvent‐free conditions, whereas the diphenylphosphinoylmethyl derivatives were synthesized in acetonitrile solution. Comparative thermal experiments showed the beneficial role of MW in respect of efficiency.

A study on the deoxygenation of trialkyl‐, dialkyl‐phenyl‐ and alkyl‐diphenyl phosphine oxides by hydrosilanes

“…It is a green chemical approach to substitute catalysts by MW irradiation. We experienced that in heterogeneous phase C‐alkylations, and in Kabachnik‐Fields reactions, the catalysts could be omitted under MW conditions. It was shown above that this approach was utilized in the TMDS‐ and PMHS‐promoted deoxygenations .…”

<strong>Synthesis of &alpha;-aminophosphonates and related derivatives under microwave conditions</strong>

“…α-, β-and γ-Amino acids and esters were also suitable amine components in the condensation. The corresponding bis(dialkoxyphosphonylmethyl)amino acid derivatives (8) were obtained in yields of 61-97% [29,30].…”

“…The double Kabachnik-Fields condensations were also carried out applying secondary phosphine oxides (Scheme 3) [26][27][28][29][30]. To overcome the heterogeneity of the reaction mixture, the reactions were carried out in acetonitrile.…”

The Use of MW in Organophosphorus Chemistry

“…α-, β-and γ-amino acids (or esters) (60) were also utilized in the double Kabachnik-Fields condensation to furnish the bis(phosphono-or phosphinoyl) products (61) (Scheme 3.42) [81,82].…”