Design of potential new HIV protease inhibitors: enantioconvergent synthesis of new pyrrolidin-3-ol, and pyrrolidin-3-one peptide conjugates
作者:Jérôme Courcambeck、Frédéric Bihel、Céline De Michelis、Gilles Quéléver、Jean Louis Kraus
DOI:10.1039/b101584m
日期:——
Novel potential HIV protease inhibitors are obtained by an enantioconvergent synthesis of mimicking Phe-Pro dipeptides, achieved through the coupling between Boc(L)Phe or Boc(L)Tyr and both enantiomers of syn-2-benzylpyrrolidin-3-ol and their corresponding pyrrolidin-3-one analogs. The stereochemistry and enantiopurity of intermediate 3-hydroxypyrrolidines 5a and 5b are determined through 1H NMR analysis, and through the synthesis and 19F NMR assignments of the corresponding Mosher’s esters 13a and 13b. The enantiopure compounds 5a and 5b are obtained with 100% diastereoselectivity using specific experimental reductive conditions upon Meldrum’s acid derivatives of activated aromatic amino acids.
A Synthetic Approach to Diverse 3-Acyltetramic Acids via <i>O</i>- to <i>C</i>-Acyl Rearrangement and Application to the Total Synthesis of Penicillenol Series
efficient approach to medicinally important α-branched 3-acyltetramicacids, the key reaction of O- to C- acyl rearrangement using α-amino-acid-derived 4-O-acyltetramic acids was extensively examined in the presence of various metal salts. Use of CaCl2 or NaI dramatically changed the results in the reaction efficiency and rapidly brought about the desired α-branched 3-acyltetramicacids in markedly
(S)-3-(Dimethylamino)methylidene-5-benzyltetramic acid derivatives 4a and 4b were prepared in three steps from N-protected (S)-3-phenylalanines 1a and 1b, respectively. Similarly, N-[N-(benzyloxycarbonyl)glycyl]glycine (1c) was transformed into the enaminone 4c. Acid-catalysed coupling of enaminones 4a-c with aliphatic, aromatic, and heteroaromatic primary amines 5-34 afforded the corresponding N(3′)-substituted 3-aminomethylidenetetramic acid derivatives 35-64 in 29-96% yields.
The synthesis of chiral N-protected tetramic acid derivatives which are important precursors of β-hydroxy γ-amino acid under mild conditions is described. Reaction of urethane-N-carboxyanhydrides (UNCAs) with Meldrum's acid in the presence of a tertiary amine, followed by subsequent cyclisation produced tetramic acid derivatives. This procedure is applicable to Boc-, Fmoc- and Z- N-carboxyanhydrides