Scheme 2.

Synthesis of intermediate 7^a

^a Regents and conditions: (a) i-PrOH, H₂SO₄ (conc.), reflux, 80%; (b) i) LHMDS, Pd₂(dba)₃, P(t-Bu)₃, Toluene, rt; ii) 1N HCl, rt, 90%; (c) Boc₂O, THF, reflux, 85%; (d) THF, −78 °C; (e) LiOH, MeOH/H₂O (2/1), reflux, 85%, two steps; (f) EDCI, HOBt, TEA, 10, 4Å MS, DCM, 0 °C to rt, 73%; (g) 10% Pd/C, 60 psi, MeOH, 84%; (h) i) LiAlH₄, THF, 0 °C to rt; ii) H₂O, NaOH, 71%.