Diaryl phosphite

Considerably higher product yields resulted under much milder conditions when diaryl phosphites were condensed with ffilTs. Whereas vigorous neat conditions and temperatures exceeding 100 °C were usually necessary with aliphatic phosphites, often quantitative conversions to the desired glyphosate derivatives were obtained in common organic solvents using aromatic or benzylic phosphites (40). 

In contrast, when excess amounts of the HHTs derived from simple aliphatic glycinate esters, such as 25, were used in excess in reactions with diaryl phosphites (SO), the related glyphosate aminals containing aryl phosphonate esters 46 were isolated in low yield (5-15%). Like many aminals, these triesters 46 were acid-sensitive and were quantitatively converted to the corresponding triester strong acid salts 47 upon treatment with either HCl or methanesulf onic acid (27). 

Many other examples have been prepared (2) from the corresponding aminomethyl heterocycles using the very versatile reaction between HHTs and diaryl phosphites, as demonstrated specifically above for the 5-phenyl-l,3,4-oxadiazole system. Conversion of the 2-aminomethyl-l,3,4-oxadiazole 68 to the required HHT intermediate 69 was accomplished... 

Michael addition in the absence of any catalytic agent has been reported for dialkyl and diaryl phosphites and thiophosphites with a-cyanoacrylate esters and a-cyanoacrylic acid.444 Yields of the conjugate addition products were moderate to good. The regiochemistry of this process is the opposite of that previously reported for similar additions to ketene acetals, the latter presumably proceeding by initial protonation of the distal olefinic carbon site.445... 

Kolomnikova, G.D., Prichodchenko, D.Y., Petrovskii, P.V., and Gololobov, Y.G., Interaction of a-cyanoacrylic acid and a-cyanoacrylates with dialkyl and diaryl phosphites, Izv. Akad. Nauk, Ser. Khim., 1913, 1992. 

The P—S bond formation of dialkyl (or diaryl) phosphites (21) with disulfide proceeds in an MeCN-NaBr/Et4NCl04-(Pt) system at 20 25 °C, giving phos-phorothiolates (22) in 72 91% yields (Scheme 9) [51]. In this reaction, both sodium iodide and sodium chloride are less effective than sodium bromide. Depending on the nature of the cation, the yields of (22) decrease in the order of Na+ (91%) > K+ (76%) > Li+ (69%) > Et4N+ (46%). 

Scheme 9 Phosphorothiolates from dialkyl- and diaryl phosphites. 

Similarly, the phosphorus-sulfur bond can be generated starting from dialkyl or diaryl phosphites (Eq. (56) Table 4, No. 35)... 

Recently, efforts have been made to categorize the effects that influence stereoselectivity in the reaction of phosphites with chiral aldimines42. The reaction of a series of dialkyl or diaryl phosphites with aldimincs obtained from enantiomerically pure 1-phenylethylamine and various substituted benzaldehydes were examined in detail and the following conclusions were drawn42 ... 

Table 3. Steric Effects of Dialkyl or Diaryl Phosphites on Addition to ( — )-(S)-l-Phe-nyl-A-benzylideneethylamine (X = H) in the Formation of Amino Phosphonate 942...

As this chapter covers two years of the literature relating to the above area, it has been necessary to be somewhat selective in the choice of publications cited. Nevertheless, it is hoped that most significant developments have been noted. As in previous reports, attempts have been made to minimise the extent of overlap with other chapters, in particular those concerned with the synthesis of nucleic acids and nucleotides to which the chemistry of tervalent phosphorus esters and amides contributes significantly, the use of known halogen-ophosphines as reagents for the synthesis of phosphines (see Chapter 1), and the reactions of dialkyl- and diaryl-phosphite esters in which the contribution of the phosphonate tautomer, (R0)2P(0)H), is the dominant aspect, which are usually covered elsewhere in these volumes. 

Diaryl phosphites have been reported to form in nearly quantitative yield by the simultaneous addition of phosphorus trichloride and 38% hydrochloric acid (fuming HCI) to a two molar proportion of phenol, continuation of stirring for 2 hours and standing of the mixture during 8-10 hours (ref.32). 

Torii S, Tanaka H, Sayo N (1979) Electrosynthesis of hetero-hetero atom bonds 4. Direct cross-coupling of dialkyl(or diaryl)phosphites with disulfides by a sodium bromide promoted electrolytic procedure. J Org Chem 44 2938-2941... 

Hayashi and Nakamura have reported a synthesis of optically active phosphoric esters (135) through the catalytic, enantioselective protonation of a-phosphonyloxy enolates, which were prepared in situ from the nucleophilic addition reaction of diaryl phosphites (134) to a-ketoesters (133) and a subsequent phospha-Brook rearrangement (Seheme 35). ... 

The cinchonine catalysed Pudovik reaction between dialkyl or diaryl phosphites (576) and a-haloketones (577) has been used to synthesise... 

---