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. Author manuscript; available in PMC: 2009 Jan 8.
Published in final edited form as: J Am Chem Soc. 2006 Sep 13;128(36):11906–11915. doi: 10.1021/ja062364i

Scheme 5a.

Scheme 5a

a Reagents and conditions: (a) TBSCl, imid, DMF (74%); (b) TIPSCl, AgNO3, imid, DMF (48% β (and 40% α)); (c) K2CO3, MeOH (98%); (d) allyl-OH, MeCOCl (77%, 3:1, α: β); (e) BnCl, NaH, 95 °C (45%); (f) KO-t-Bu, DMSO, 100 °C; then HCl, acetone, reflux (71%); (g) Ac2O, Et3N, CH2Cl2 (84%); (h) HBr, AcOH, CH2Cl2; (i) o-NO2-BnOH, Ag2O, CH2Cl2 (58%, 2 steps); (j) K2CO3, MeOH (90%); (k) Bu2SnO, BnBr, Bu4NBr, PhCH3 (40%); (l) TBSCl, imid, DMF (96%); (m) Ac2O, DMAP, CH2Cl2 (84%); (n) p-TsOH, MeOH (72%).