摘要 |
A process for preparing a compound of the formula (I): wherein X is H, halogen, CO2R3, OR4, COR5, or a fibrinogen or vitronectin antagonist side chain; R2 is C1-6alkyl, optionally substituted by Ar, Het or C1-6cycloalkyl; R3 is C1-6alkyl or benzyl; R4 is Cl-6alkyl, COR3 or benzyl; R5 is 4,4'-bipiperidin-1-yl, (1' -benzyloxycarbonyl)-4 ,4' -bipiiperidin-l-yl, or (l'-t- butoxycarbonyl)-4,4'-bipiperidin-1 -yl; which comprises: a) treating a compound of the formula (II): wherein R1 is C1-20alkyl or C3-20alkenyl, optionally substituted by Ar, NR2 or NR3+, wherein R is C1-4alkyl; with Candida Antarctica lipase B; b) and separating the resulting 2,3,4,5-tetrahydro-4-methyl-3-oxo-1H-1,4-benzodiazepine-2- acetic acid carboxylic acid from the corresponding ester.
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