Mechanism of the reaction in Table 2? Hint: Ignore the catalyst, and note that your mechanism (basically the placement of the reactants in your mechanism) should explain the stereochemistry.
Table 2. Purification Improves Stereoselectivity
OSi(CH3)3 CH3+ ph H
OH
[I (48 mol%) + Eu(OTf)3 (20 mol%)] EtOH/H2O (0.4 mL, 9:1 v/v) Ph 25°C, 168 h 2a
CH3 3a
1a
syn:anti = 4:1 85 26:1
syn:anti = 5:1
syn:anti = 16:1 89 28:1
syn:anti >99:
ligand I yield (%)b 88 92 product 26:1 32:1 syn:anti, d er (syn)c 93:7 94:6 95:5 97:3 Reaction conditions: To a mixture of ligand I 48 mol% and Eu(OTf)3 (20 mol%), which was stirred at 50°C for 2 h and then cooled to -25°C, were added (Z)-trimethyl(1-phenylprop-1-enyloxysilane (48.8 mol, 1.5 equiv) and benzaldehyde 32.5 mol, 1.0 equiv). bIsolated yield. Determined by chiral HPLC analysis. syn:anti of 3a. esyn:anti for ligand I. JFrom ref 14. 1