反応 #161899

反応方程式

trimethyloxonium tetrafluoroborate

#3

tert-butyl (3R,4S,5S)-4-{[(benzyloxy)carbonyl](methyl)amino}-3-hydroxy-5-methylheptanoate

Proton sponge

→

tert-butyl (3R,4S,5S)-4-{[(benzyloxy)carbonyl](methyl)amino}-3-methoxy-5-methylheptanoate

溶媒

1,2-dichloroethane

反応条件

後処理

1. 1
   ろ過the reaction mixture was filtered through Celite
2. 2
   濃縮The filtrate was concentrated in vacuo
3. 3
   その他the residue was purified by silica gel chromatography (Gradient: 0% to 40% 1:1 acetone:ethyl acetate in heptane)
4. 4
   その他to give #@2 (8.7 g, 68%) as a colorless oil
5. 5
   workup.ADDITIONa mixture of rotamers
6. 6
   その他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
7. 7
   その他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)

実験手順

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).

出典