Anna Kuźnik

A new method for the synthesis of α-aminoalkylidenebisphosphonates and their asymmetric phosphonyl-phosphinyl and phosphonyl-phosphinoyl analogues

Summary A convenient approach has been developed to α-aminoalkylidenebisphosphonates and their asymmetric phosphonyl-phosphinyl and phosphonyl-phosphinoyl analogues by α-phosphonylation, α-phosphinylation or α-phosphinoylation of 1-(N-acylamino)alkylphosphonates, that, in turn, are easily accessible from N-acyl-α-amino acids. Effective electrophilic activation of the α-position of 1-(N-acetylamino)alkylphosphonates was achieved by electrochemical α-methoxylation of these compounds in methanol, mediated with NaCl, followed by displacement of the methoxy group with triphenylphosphonium tetrafluoroborate to give hitherto unknown 1-(N-acetylamino)-1-triphenylphosphoniumalkylphosphonate tetrafluoroborates. The latter compounds react smoothly with trialkyl phosphites, dialkyl phosphonites or alkyl phosphinites in the presence of Hünig’s base and methyltriphenylphosphonium iodide in a Michaelis–Arbuzov-like reaction to give the expected alkylidenebisphosphonates, 1-phosphinylalkylphosphonates or 1-phosphinoylalkylphosphonates, respectively, in good yields.

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

The main synthetic routes towards vinylphosphonium salts and their wide applications in organic synthesis are discussed in this review. Particular attention is paid to the use of these compounds as building blocks for the synthesis of carbo- and heterocyclic systems after their prior transformation into the corresponding phosphorus ylides, followed by the intramolecular Wittig reaction with various types of nucleophiles containing a carbonyl function in their structures.

N-Acyl-α-Triphenylphosphonio-α-Amino Acid Esters as Synthetic Equivalents of α-Amino Acid α-Cations

GRAPHICAL ABSTRACT Abstract Methods for the synthesis of N-acyl-α-triphenylphosphonio-α-amino acid esters and for displacement of the triphenylphosphonium group with oxygen, sulfur and nitrogen nucleophilic reagents were developed. These reactions opened up new routes for the synthesis of biologically important natural and unnatural nonproteinogenic α-amino acids by double functionalization of the glycine α-position with electrophilic and nucleophilic agents. N-Acyl-α-triphenylphosphonio-α-amino acid esters may be considered to be synthetic equivalents of the α-cation of α-amino acids.