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. Author manuscript; available in PMC: 2012 Jul 31.
Published in final edited form as: J Am Chem Soc. 2008 Dec 3;130(48):16295–16309. doi: 10.1021/ja804659n

Scheme 11.

Scheme 11

Synthesis of the ABCDE-region 77. Reagents and conditions: a) TBAF, AcOH, THF 97%; b) SO3·Pyr, DMSO, i-Pr2NEt, CH2Cl2, −30 °C, 94%; c) 71 (2 equiv), t-BuLi, Et2O, −78 °C, then 72, MgBr2·OEt2,40 CH2Cl2, −20 °C, 80%, dr > 99:1; d) Ac2O, DMAP, Et3N, CH2Cl2, 96%; e) i) O3, MeOH, CH2Cl2, −78 °C, then Me2S; ii) MeOH, HC(OMe)3, PPTS, 75% (2 steps); f) TBDPSCl, imidazole, CH2Cl2; g) DDQ, CH2Cl2/pH 7 buffer (9:1 v/v), 0 °C; 78% (2 steps); h) TESCl, imidazole, CH2Cl2, 90%; i) H2, RaNi (W-2),71 EtOH, 93%; j) SO3·Pyr, DMSO, i-Pr2NEt, CH2Cl2, −30 °C, 75%. See ref31 for abbreviations.