反应详情

To a solution of #3 (8.4 g, 22 mmol, 1 eq.) in 1,2-dichloroethane (25 mL, 0.88 M) were added molecular sieves (4 Å, 0.7 g) and Proton sponge (1,8-bis(dimethylamino)naphthalene) (13.4 g, 59.2 mmol, 2.7 eq.), followed by trimethyloxonium tetrafluoroborate (9.10 g, 61.6 mmol, 2.8 eq.). After stirring overnight, the reaction mixture was filtered through Celite. The filtrate was concentrated in vacuo and the residue was purified by silica gel chromatography (Gradient: 0% to 40% 1:1 acetone:ethyl acetate in heptane) to give #@2 (8.7 g, 68%) as a colorless oil. 1H NMR (400 MHz, DMSO-d6), presumed to be a mixture of rotamers: δ 7.28-7.40 (m, 5H), 5.01-5.13 (m, 2H), 3.89-4.08 (br m, 1H), 3.70-3.82 (m, 1H), 3.18 and 3.26 (2 s, total 3H), 2.66 and 2.71 (2 br s, total 3H), 2.44-2.53 (m, 1H, assumed; partially obscured by solvent peak), 2.17-2.24 (m, 1H), 1.71-1.86 (br m, 1H), 1.39 and 1.39 (2 s, total 9H), 1.31-1.40 (m, 1H), 0.94-1.08 (m, 1H), 0.76-0.91 (m, 6H).

1. filtrationthe reaction mixture was filtered through Celite
2. concentrationThe filtrate was concentrated in vacuo
3. customthe residue was purified by silica gel chromatography (Gradient: 0% to 40% 1:1 acetone:ethyl acetate in heptane)
4. customto give #@2 (8.7 g, 68%) as a colorless oil
5. additiona mixture of rotamers
6. customδ 7.28-7.40 (m, 5H), 5.01-5.13 (m, 2H), 3.89-4.08 (br m, 1H), 3.70-3.82 (m, 1H), 3.18 and 3.26 (2 s, total 3H), 2.66 and 2.71 (2 br s, total 3H), 2.44-2.53
7. custom2.17-2.24 (m, 1H), 1.71-1.86 (br m, 1H), 1.39 and 1.39 (2 s, total 9H), 1.31-1.40 (m, 1H), 0.94-1.08 (m, 1H), 0.76-0.91 (m, 6H)