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. Author manuscript; available in PMC: 2010 Feb 10.
Published in final edited form as: J Am Chem Soc. 2009 Jan 28;131(3):943. doi: 10.1021/ja8084934

Scheme 3.

Scheme 3

Synthesis of Divinylamide Fragment 4 through Ru-Catalyzed ROCMa

a (a) 4.0 equiv of NaN3, 2.0 equiv of Tf2O, 1.0 mol % TBAB, 2.0 M NaOH, petroleum ether/MeCN, 0 °C, 30 min; 66% yield. (b) 1.0 mol % Rh2(OAc)4, HCCSiMe3, 55 °C, 20 h; 64% yield. (c) 3.7 mol % KOH, EtOH, 0 °C, 5 min; 93% yield. (d) 1.3 equiv of HCl · HNMe(OMe), 2.6 equiv of i-PrMgCl, THF, 0 °C →22 °C, 30 min; pH 7 buffer. (e) 2.3 equiv of DMSO, 2.0 equiv of (COCl)2, CH2Cl2, 7.4 equiv of Et3N, −78 °C → 22 °C; 86% overall yield for two steps.