aConditions: (a) O3ReOSiPh3, Et2O, 5 min, 78% (97% brsm); (b) Dess-Martin periodinane, CH2Cl2; (c) (R)-Me-CBS, BH3·THF, THF, 93% over 2 steps; (d) (+)-DET, Ti(i-OPr)4, TBHP, 4 Å MS, CH2Cl2, 88%; (e) DDQ, CH2Cl2/pH7 buffer/tert-BuOH, 89%; (f) (+)-DET, Ti(i-OPr)4, TBHP, 4 Å MS, CH2Cl2, 86%; (e) DDQ, CH2Cl2/pH7 buffer/tert-BuOH, 71%.