Draw a plausible mechanism for each of the synthetic steps in this
scheme
Me Me OBn...
Me Me OBn OBn 10 Me OMe OBn OBn 11 R Ts 12 R Tf Scheme2. Reagents and conditions: a) BH33M02 THF, TEA, 8 (10 mol%), RT, 8 h (> 95% ee); b) TsNHCH2CH(OMe)2 (13, 3 equiv.), PPh3 (3 equiv.), DEAD (3 equiv.), pyridine (1 equiv.), toluene, RT, 3 h (64%, >95% ee) orTiNHCH2CH(OMe)2 (14), PPh3, DEAD, toluene, (14),PPhi. DBA, toluene, % RT, 3 h, complex mixture; c) 6 N HCl, dioxane, reflux (82%.> 95% ce).