engleski

Attempted diastereoselective preparation and chiroptical properties of (2S)-1-(3-mercapto-2-methyl-1-oxopropyl)-L-proline (captopril) and some congeners

CD and 13C-NMR study of the conformational properties of (2S)-1-(3-mercapto-2-methyl-1-oxopropyl)-L-proline (captopril, 1), and its congeners 2-5, 8, 9 is reported. 13C-NMR data (in DMSO-d6) reveal an E/Z (cis/trans) ratio of ca. (15-30) : (70-85) for the N-acyl-prolines 1, 5, 10, and for N-acetyl-L-proline. CD data indicate practically identical conformations for the ring systems of 8 and 9. Attempted diastereoselective cyclization of the sodium salt of 7 or the free thioacid into 8 and 9 resulted in low chemical yields (~30%) and low diastereoselectivity, favouring formation of the "wrong" diastereomer 9 in small excess (~20%).

(2S)-1-(3-mercapto-2-methyl-1-oxopropyl)-L-proline (captopril, 1)

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