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. Author manuscript; available in PMC: 2014 Aug 8.
Published in final edited form as: J Med Chem. 2013 Jul 18;56(15):6216–6233. doi: 10.1021/jm400664x

Scheme 6a. Synthesis of the precusor (-)-33.

Scheme 6a

aReagents and conditions:

(a) Separation of enantiomers of 6 on HPLC: column: Chiralcel OD; mobile phase: 34% isopropanol in hexane; flow rate: 4.0 mL/min; (+)-enantiomer at 20.8 min and (-)-enantiomer at 33 min; (b) (Boc)2O, DMAP, Et3N, THF, rt., 1.5 h; (c) K2CO3, MeOH, reflux, overnight.