Scheme 18.

Preparation of compound 105 needed for the total synthesis of RvT4 (29) and RvT1 (26) by Rodriguez and Spur [62]. Reagents and conditions: (i) TMSCl, 2,2-dimethoxypropane, CH₃OH, rt; (ii) porcine pancreatic lipase, 0.05 M phosphate buffer pH 7, 1 N NaOH; (iii) (COCl)₂, cat. DMF, CH₂Cl₂, rt; (iv) BTMSA, AlCl₃, CH₂Cl₂, 0 °C; (v) RuCl[(S,S)-TsDPEN](p-cymene), cetrimonium bromide (CTAB), HCOONa, H₂O, EtOAc, rt; (vi) TBSCl, imidazole, 4-DMAP, CH₂Cl₂, 0 °C to rt; (vii) K₂CO₃, Na₂SO₄, CH₃OH, rt; (viii) (Bu)₃SnH, AIBN, benzene, reflux; (ix) I₂, CH₂Cl₂, 0 °C.