Mirosława Grymel

N-Acyl-a-triphenylphosphonioglycinates:A Novel Cationic Glycine Equivalent and its Reactions with Heteroatom Nucleophiles

Summary. Two simple and convenient methods of transforming easily accessible 4-phosphoranylidene-5(4H)-oxazolones into N-acyl-α-triphenylphosphonioglycinates are described. N-Acyl-α-triphenylphosphonioglycinates react smoothly with heteroatom nucleophiles in the presence of DBU or triethylamine yielding the corresponding α-functionalized glycine derivatives.Zusammenfassung. Zwei einfache Methoden zur Überführung der leicht zugänglichen 4-Phosphoranyliden-5(4H)-oxazolone in N-Acyl-α-triphenylphosphonionoglycinate werden beschrieben. Die N-Acyl-α-triphenylphosphonionoglycinate reagieren leicht mit Heteroatomnucleophilen in Gegenwart von DBU oder Triethylamin zu den entsprechenden α-funktionalisierten Glycinderivaten.

N-Acyl-α -triphenylphosphonio-α -amino Acids: Synthesis and Decarboxylation to α -(N-Acylamino)alkyltriphenylphosphonium Salts

4-Phosphoranylidene-5(4H)-oxazolones 1 undergo hydrolysis in THF in the presence of HBF 4 at room temperature to give N-acyl-α -triphenyphosphonioglycines 3 (R 2 = H) in very good yields. 4-Alkyl-4-triphenylphosphonio-5(4H)-oxazolones 2 react with water in CH 2 Cl 2 /THF solution without any acidic catalyst at 0–5°C in a few days yielding N-acyl-α -triphenylphosphonio-α -amino acids 3 (R 2 = Me) or α -(N-acylamino)alkyltriphenylphosphonium salts 4 (R 2 = alkyl, other then Me). α -Triphenylphosphonio-α -amino acids 3 upon heating to 105–115°C under reduced pressure (5 mm Hg) or upon treatment with a Hünig base in CH 2 Cl 2 at 20°C undergo decarboxylation to give the corresponding α -(N-acylamino)-alkyltriphenylphosphonium salts 4 , usually in very good yields.

A NEW SYNTHESIS OF α-AMINO ACID DERIVATIVES BY REACTION OF N-ACYL-α-TRIPHENYLPHOSPHOSPHONIO-GLYCINATES WITH CARBON NUCLEOPHILES

Abstract Recently described1, easily accessible N-acyl-α-triphenylphosphonioglycinates react smoothly with activated carbonyl compounds or enamines in the presence of a base (DBU or Et3N) yielding the corresponding α-functionalized glycine derivatives.

β-Aminovinylphosphonium Salts—A Novel Synthesis, Properties, and Structure

The deacylation of easily accessible β-(N-acylamino)vinylphosphonium salts with methanol or some other nucleophiles gives β-aminovinylphosphonium salts in good yields. As indicated by the spectroscopic properties and by the results of single crystal X-ray diffraction studies the N-alkyl derivatives of the investigated compounds should be considered as strongly resonance stabilized β-iminium ylides rather than β-aminovinylphosphonium salts. In the case of N-aryl derivatives, the β-iminium ylide resonance structures are probably less pronounced.

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.