合成路线1

Alternatively, (-)-(XVII) can be obtained as follows: Treatment of (X) with 1-acetoxy-2-bromoethane (XVIII) in DMF in the presence of NaHCO3 yields derivative (XIX), which is then chlorinated by means of SO2Cl2 in CH2Cl2 to provide (XX). Simultaneous hydrolysis and intramolecular cyclization of (XX) by means of Et3N /H2O in THF affords (XXI), which is then converted into octyl ester derivative (XXII) by treatment with refluxing octanol (A). Resolution of the racemic mixture (XXII) by treatment with Liposyme IM in vinyl acetate followed by chromatographic separation provides alcohol (+)-(XXIII) and acetoxy (-)-(XXIV). Hydrolysis of (-)-(XXIV) with hot H2SO4/EtOH gives alcohol (-)-(XXV), which then reacts with 1-methylpiperazine (XVI) in DMF to yield derivative (-)-(XXVI). Finally, treatment with (diethylamino)sulfur trifluoride (DAST) in CH2Cl2 provides fluoro derivative (-)-(XVII). Alternatively, (-)-(XXV) can be obtained by conversion of (XXI) into butyl ester (XXVII) by means of refluxing butanol (B), followed by its enantiomer enzymatic resolution with Lipase PL in vinyl acetate and chromatographic separation to afford (+)-(XXVIII) and (-)-(XXIX). Finally, hydrolysis of (-)-(XXIX) with hot H2SO4/EtOH yields (-)-(XXV). An analogous procedure comprising enantiomer separation and subsequent hydrolysis can be performed from ethyl esters (XX) or (XXI) by treatment with the corresponding lipases in an appropriate solvent.