Scheme 3.

Synthesis of the C₁₆ Benzyloxy-Substituted Aldehyde^a

^a Key: (i) BnOLi, PMBOH, THF, 99%; (ii) AD mix α, NaHCO₃, t-BuOH, H₂O; (iii) TIPSOTf, 2,6-lutidine, CH₂Cl₂, −78 °C, 66% overall yield from 16 (3:1 d.s.); (iv) LiBH₄, MeOH, THF, 0 °C, 99%; (v) PivCl, Et₃N, DMAP, CH₂Cl₂, 66%; (vi) NaH, BnBr, DMF, −50 °C to −10 °C; (vii) TBAF, THF, 79% (over two steps); (viii) TESCl, DMAP, Et₃N, CH₂Cl₂, 95%; (ix) LiBH₄, saturated aqueous NH₄Cl, THF, 0 °C to rt, 99%; (x) TPAP, NMO, CH₂Cl₂, molecular sieves, 87%.