594247.sch.004
Scheme 4: (a) MeOH/HCl; (b) Ac2O/Py; (c) AcCl, MeOH/CHCl3; (d) Ag2CO3/AgOTf, CH2Cl2, MS 4Å; (e) MeONa/MeOH; (f) NaOH/H2O.