| abstract |
processes and intermediates for preparing a macrocyclic hcv protease inhibitor. The present invention relates to a process for preparing (1r, 2r) -4-oxo-1,2-cyclopentanedicarboxylic acid ii by resolving racemic 4-oxo-1,2-cyclopentanedicarboxylic acid (v), wherein the said process comprises: a) reacting 4-oxo-1,2-cyclopentanedicarboxylic acid (v) with brucine or (1r, 2s) - (-) - ephedrine, thereby preparing the bis-brucine or bis- (1r, 2s) salt - (-) - ephedrine from (v), and b) selectively precipitate the bis-brucine or bis (1r, 2s) - (-) - ephedrine salt of (1r, 2r) -4-oxo-1,2- cyclopentanedicarboxylic acid ii, whereas the bis (brucine or bis (1r, 2s) - (-) - ephedrine salt of [(1s, 2s) -4-oxo-1,2-cyclopentanedicarboxylic acid remains in solution; c) releasing acid ii by removing brucine or (1r, 2s) - (-) - ephedrine from the precipitated salt obtained in step (b). |