130521-05-0Relevant articles and documents
The synthesis of DL-3,3-difluoroglutamic acid from a 3-oxoprolinol derivative
Hart,Coward
, p. 4917 - 4920 (1993)
DL-3,3-Difluoroglutamic acid was synthesized from a masked 3-hydroxyprolinol, 6-hydroxy-1-aza-3-oxabicyclo[3,3,0]octan-2-one, in eight steps. The described synthetic route expands the utility of fluoroproline derivatives as precursors of fluoroglutamic acids.
δ,ε-Unsaturated β,β-Difluoro-α-keto Esters: Novel Synthesis and Utility as Precursors of β,β-Difluoro-α-amino Acids
Shi, Guo-qiang,Cai, Wei-ling
, p. 6289 - 6295 (2007/10/03)
Treatment of the hemiketals 6 formed from ethyl trifluoropyruvate and primary allylic alcohols with SOCl2 and pyridine readily afforded a number of α-chloro-β,β-trifluorolactyl allyl ethers 2.Subsequent reductive dechlorofluorination from 2 led to the formation of allyl-substituted difluoroenol pyruvyl ethers 3 whose Claisen rearrangement provided a convenient access to a variety of δ,ε-unsaturated β,β-difluoro-α-keto esters 4.As further transformation, direct conversion of β,β-difluoro-α-keto esters to the corresponding β,β-difluoro-α-amino acids was achieved by reductive amination of the corresponding α-keto acids with NH3*H2O/NaBH4.Furthermore, use of the prepared β,β-difluoro-α-keto ester 4a as a common precursor of other structurally related β,β-difluoro-α-amino acids was demonstrated by the synthesis of β,β-difluoroproline (18) and β,β-difluoroglutamic acid (23) through synthetic elaboration of its inherent double bond.
