*3.4. Copper-Catalyzed Asymmetric Desymmetrization of 2-O-Benzylglycerol*

The reaction was performed using 2-*O*-benzylglycerol (**4**, 182 mg, 1.0 mmol) [69] according to the procedure described in Section 3.2. Silica gel column chromatography (hexane/acetone = 3/1) to afford (*S*)-**5** (52.6 mg, 0.16 mmol, 16% yield).

*(S)-2-(Benzyloxy)-3-hydroxypropyl 4-methylbenzenesulfonate* ((*S*)-**5**). colorless oil; [α]D<sup>21</sup> −2.1 (*<sup>c</sup>* 1.00, CHCl3) for 7% ee; 1H NMR (400 MHz, CDCl3): *<sup>δ</sup>* 7.78 (d, *<sup>J</sup>* = 8.2 Hz, 2H), 7.36–7.27 (m, 7H), 4.63 (d, *J* = 11.7 Hz, 1H), 4.55 (d, *J* = 11.7 Hz, 1H), 4.17–4.10 (m, 2H), 3.75–3.67 (m, 2H), 3.62–3.56 (m, 1H), 2.45 (s, 3H), 1.80 (t, *J* = 6.3 Hz, 1H); 13C{1H} NMR (125 MHz, CDCl3): *δ* 145.0, 137.5, 132.6, 129.9, 128.5, 128.1, 128.0, 127.9, 76.7, 72.5,

68.7, 61.4, 21.7; IR (ATR): 3445, 3032, 2879, 1597, 1354, 1173, 974 cm−1; HRMS (ESI) *m*/*z*: [M + Na]+ calcd for C17H20NaO5S 359.0929, found 359.0922; HPLC analysis: Chiralpak AD, hexane/EtOH = 3/1, flow rate 1.0 mL/min, wavelength 254 nm, *t*<sup>R</sup> 7.1 min (minor) and 8.8 min (major). The absolute configuration of **5** was established by comparing the sign of the specific rotation of **5** with the literature value ([α]D<sup>22</sup> +29.5 (*c* 1.01, CHCl3) for (*R*)-**5**) [70].
