| Abstract
| - New 1,5-dimethyl-4-phenylimidazolidin-2-one-derived acyclic chiral iminic glycine reagents havebeen prepared and diastereoselectively alkylated with activated alkyl halides and electrophilic olefinsin the presence of lithium chloride under (a) strong bases (LHMDS, KOBut) and low temperature(−78 °C) conditions, (b) solid−liquid phase-transfer catalysis reaction (LiOH, TBAB, −20 °C)conditions, and (c) in the presence of organic bases (DBU, BEMP, TMG, −20 °C). In the case ofdielectrophiles C- and N-alkylation takes place to afford heterocyclic derivatives. Hydrolysis ofalkylated products has been carried out (a) in two-step procedures with LiOOH or LiOH followedby acidic hydrolysis or Dowex purification, (b) in one single-step under refluxing water to give thecorresponding α-amino acid, (c) in the presence of DBU in methanol to provide N-protected α-aminoacids methyl esters, or (d) by a protection−hydrolysis procedure to afford N-Boc-protected α-aminoacids. The chiral imidazolidinone has generally been recovered in good yield. This methodologyhas been shown to be useful for the synthesis of acyclic and heterocyclic (S)- and (R)-α-amino acids.
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