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Synthesis of aromatic A ring fragments (31a and 31b).
Key: a) Br2, CHCl3; b) ClCONEt2, pyridine, DMAP, reflux, 48% over 2 steps; c) TBSOTf, lutidine, CH2Cl2, 0 °C→RT, 97%; d) mCPBA, CH2Cl2; e) K2CO3, MeOH; f) MOMCl, i-Pr2NEt, 31a: 58% over 3 steps; g) TMSCHN2, PhH, MeOH, 31b: 65% over 3 steps.
