Reaction Steps
BH3.Me2S (250 μL, 2M in THF, 0.5 mmol) was added dropwise to a solution of 6a (50 mg, 0.11 mmol) in dry THF (4 mL) at rt. The reaction vessel was sealed and heated for 60 s at 100° C. using microwave irradiation. The reaction mixture was cooled to room temperature, diluted with CH2Cl2, poured onto ice-cold aqueous HCl (1M) and agitated. The pH was then adjusted to ˜10 with 2M aqueous NaOH and the aqueous layer was extracted with CH2Cl2. The combined organic layers were dried and concentrated. The crude product was dissolved in MeOH and swirled with Amberlyst 15. The solid phase was transferred to a filtration funnel and washed with MeOH. The product was released by addition of 10% NH3 in MeOH and eluted with MeOH. Concentration of the filtrate gave 7a as a yellow solid (36 mg, 72%): [α]D−44 (c 0.25, CHCl3); IR λ 2958, 2854, 1747, 1631, 1492, 1440, 1259, 1214 cm−1; 1H NMR (400 MHz, CDCl3) δ7.83 (d, J=8.2, 1H), 7.78 (d, J=8.1, 1H), 7.71 (d, J=8.7, 1H), 7.54-7.00 (m, 9H), 5.74 (dd, J=8.6, 2.7, 1H), 4.25-4.11 (m, 2H), 3.96-3.51 (m, 8H), 3.48 (dd, J=11.8, 2.7, 1H); 13C NMR (100 MHz, CDCl3) δ168.1, 161.3, 153.5, 148.9, 135.8, 133.8, 133.6, 131.2, 129.7, 129.3, 128.7 (splitted), 128.5 (splitted), 127.3, 126.3, 125.9, 125.5, 124.4, 123.2, 118.4, 116.6, 64.2, 53.6, 38.0, 33.2, 31.7; HRMS (FAB+) calcd for C27H24N2NaO3S 479.1405, obsd 479.1405.
