Reaction Steps
To a dry THF (200 mL) solution containing ((2R,3S,6R)-3-acetoxy-6-cyano-3,6-dihydro-2H-pyran-2-yl)methyl acetate (5.5 g, 23 mmol), diphenylsilane (8.47, 46 mmol) and zinc chloride (7.52 g, 55.2 mmol) was added after N2 bubbling, Pd(PPh3)4 (2.66 g, 2.30 mmol). The reaction mixture was stirred at 23° C. for 4 h. (monitored by TLC). The reaction mixture was filtered through a short silica gel column using CH2Cl2 as solvent. The solvent was removed under reduced pressure and the crude material was purified by a silica gel column (Biotage flash chromatography system) using ethyl acetate:hexane (1:5) to (1:2) to afford 2.8 g (67% yield) mixture of ((2S,6R)-6-cyano-5,6-dihydro-2H-pyran-2-yl)methyl acetate and((2S,6R)-6-cyano-3,6-dihydro-2H-pyran-2-yl)methyl acetate. 1H NMR (400 MHz, CDCl3) δ ppm 6.06-6.15 (0.5 H, m, J=7.6, 5.3, 2.8, 2.8 Hz), 5.93-6.02 (0.5 H, m, J=10.4, 5.2, 2.6, 2.6 Hz), 5.69-5.79 (1 H, m), 4.54 (0.5 H, dd, J=9.9, 3.8 Hz), 4.48 (0.5 H, m), 4.11-4.23 (2 H, m), 3.89 (1 H, m), 2.59-2.69 (1 H, m), 2.33-2.42 (1 H, m,), 2.16-2.22 (1 H, m), 2.14 (3 H, s), 2.12 (3H, s). To the mixture of ((2S,6R)-6-cyano-5,6-dihydro-2H-pyran-2-yl)methyl acetate and ((2S,6R)-6-cyano-3,6-dihydro-2H-pyran-2-yl)methyl acetate. (2.6 g, 14.4 mmol) in ethyl acetate (200 mL) was added Pd/C (5%) (0.200 g). The reaction mixture was stirred at 23° C. for 6 h. under a hydrogen atmosphere (balloon). The Pd/C was then removed by filtration and the solvent evaporated in vacuo to afford 2.20 g (84% yield) of the target compound. 1H NMR (400 MHz, CDCl3) δ ppm 4.28 (1 H, dd, J=11.7, 2.7 Hz), 4.03-4.14 (2 H, m), 3.59-3.67 (1 H, m), 2.11 (3 H, s), 1.94-2.04 (2 H, m), 1.80-1.91 (1 H, m), 1.54-1.65 (2 H, m), 1.33-1.45 (1 H, m).
