*3.2. Copper-Catalyzed Asymmetric Desymmetrization of Glycerol*

A solution of (*R*,*R*)-PhBOX (33.4 mg, 0.10 mmol) and CuCN (8.96 mg, 0.10 mmol) in CH2Cl2 (4.0 mL) was stirred for 3 h at 40 ◦C. The reaction mixture was allowed to cool to room temperature and filtered into a round bottom flask using a cotton plug. After removal of the solvent under reduced pressure, the resulting solid was dried in vacuo for 30 min. To the round-bottom flask containing CuCN/(*R*,*R*)-PhBOX was added a solution of glycerol (92.1 mg, 1.0 mmol) in acetone (4.0 mL), and the resulting mixture was stirred for 10 min at room temperature. To the mixture was successively added Na2CO3 (159 mg, 1.5 mmol) and TsCl (229 mg, 1.2 mmol), and the mixture was stirred for 3 h at room temperature. The reaction was quenched with saturated aqueous NH4Cl, and the resulting mixture was extracted with AcOEt. Combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (hexane/AcOEt = 1/2) to afford (*R*)-**2** (236 mg, 0.96 mmol, 96% yield).

*(R)-2,3-Dihydroxypropyl 4-methylbenzenesulfonate* ((*R*)-**2**). White solid; mp = 56–58 ◦C; [α]D<sup>23</sup> −8.3 (*<sup>c</sup>* 1.00, MeOH) for 94% ee; 1H NMR (400 MHz, CDCl3): *<sup>δ</sup>* 7.81 (d, *<sup>J</sup>* = 8.5 Hz, 2H), 7.37 (d, *J* = 8.5 Hz, 2H), 4.13–4.06 (m, 2H), 3.99–3.93 (m, 1H), 3.74–3.69 (m, 1H), 3.66–3.60 (m, 1H), 2.51 (d, *J* = 5.5 Hz, 1H), 2.46 (s, 3H), 1.94 (t, *J* = 5.9 Hz, 1H); 13C{1H} NMR (100 MHz, CDCl3): *δ* 145.2, 132.2, 130.0, 127.9, 70.7, 69.6, 62.7, 21.6; IR (ATR): 3368, 2926, 1350, 1171, 968, 812 cm<sup>−</sup>1; HRMS (EI) *m*/*z*: [M]+ calcd for C10H14O5S 246.0562, found 254.0562; HPLC analysis: Chiralpak AY-H, hexane/EtOH = 2/1, flow rate 1.0 mL/min, wavelength 254 nm, *t*<sup>R</sup> 13.5 min (minor) and 15.6 min (major). The absolute configuration of **2** was established by comparing the sign of the specific rotation of **2** with the literature value ([α]D<sup>22</sup> −9.3 (*<sup>c</sup>* 4.99, MeOH) for (*R*)-**2**) [68].
