N-acyl oxazolidinones of simple carboxylic acids and amino acids were observed to undergo successful SmI2-promoted couplings with substituted acrylamides and acrylates, affording a variety of functionalized gamma-ketoamides and -esters with yields attaining 85%. As many of these reductive couplings were previously found to be ineffective employing the corresponding 4-pyridylthio esters, the applicability of this methodology has been substantially improved. The methodology has been adapted to prepare structures related to two potent aspartate protease inhibitors, the renin inhibitor aliskiren, and the gamma-secretase inhibitor L-685,458. Finally, a convenient two-step procedure for the preparation of N-acyl oxazolidinones of N-protected amino acids, which provides consistently good yields of the corresponding imide, has been devised.
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