Reaction Steps
Bis(2-methoxyethoxy)-aluminum hydride (65+ wt % in toluene, 3 equiv.) was added dropwise to a stirred solution of 7,13-diacetylbaccatin III (170 mg, 253 μmol) in dry THF (2 mL) at 0° C. After stirring for 30 minutes at 0° C., the reaction was quenched by dropwise addition of saturated NH4Cl. The mixture was stirred for 10 minutes, then warmed to room temperature and diluted with EtOAc (50 mL), followed by addition of water (10 mL). The aqueous phase was separated and extracted again with EtOAc (2×25 mL). The combined organic fractions were washed with brine and water, then dried over anhydrous MgSO4. The solvent was evaporated and the crude product was purified by silica gel flash column chromatography (40–60% EtOAc gradient in hexane) to yield 2-debenzoyl-7,13-diacetylbaccatin III (see FIG. 11) (60 mg, 42% yield, 99% purity by 1H-NMR). 1H-NMR (300 MHz, CDCl3)δ: 1.04 (s, CH3), 1.22 (s, CH3), 1.77 (s, CH3), 1.85 (ddd, J=1.8, 10.8, and 14.4 Hz, H-6β), 1.90 (d, J=1.2 Hz, vinyl-CH3), 2.02 (s, C(O)CH3), 2.14 (s, C(O)CH3), 2.15 (s, C(O)CH3), 2.20 (s, C(O)CH3), 2.58 (ddd, J=7.2, 9.6, and 14.4 Hz, H-6α), 2.65 (d, J=5.1 Hz, OH at C-2), 3.58 (d, J=6.9 Hz, H-3), 3.90 (dd, J=5.4 and 6.5 Hz, H-2), 4.49 (d, J=9.6 Hz, H-20α), 4.63 (d, J=9.6 Hz, H-20β), 4.97 (dd, J=1.8 and 9.6 Hz, H-5), 5.55 (dd, J=7.2 and 10.7 Hz, H-7), 6.15 (dt, J=1.2 and 9.6 Hz, H-13), 6.18 (s, H-10), H-14 proton signal obscured. APCI-MS: m/z 567 (PH+)
