반응 #161899

반응 방정식

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

용매

1,2-dichloroethane

반응 조건

후처리

1. 1
   여과the reaction mixture was filtered through Celite
2. 2
   농축The filtrate was concentrated in vacuo
3. 3
   기타the residue was purified by silica gel chromatography (Gradient: 0% to 40% 1:1 acetone:ethyl acetate in heptane)
4. 4
   기타to give #@2 (8.7 g, 68%) as a colorless oil
5. 5
   workup.ADDITIONa mixture of rotamers
6. 6
   기타δ 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
   기타2.17-2.24 (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)

실험 절차

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).

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