Diethyl Ether → 5-Ethyl-2-oxabicyclo[2.2.1]heptan-3-one

Participants

Reaction Steps

To a scalemic mixture enriched in (1S,2R,4S)-2-ethyl-4-hydroxycyclopentanecarboxylic acid (0.943 g, 5.96 mmol) in DCM (60 mL) was added TEA (2.5 mL, 18 mmol) and BOP-Cl (1.821 g, 7.15 mmol). The reaction mixture was stirred at ambient temperature for about 2 h then poured into Et2O (350 mL). The solid was removed by filtration while washing with Et2O (50 mL). The filtrate was concd under reduced pressure to give a yellow oil which was dissolved in DCM (5 mL) and Et2O was added to give a solid. The supernatant was decanted and the solid was washed with additional Et2O. The combined organic extracts were concd under reduced pressure to give a scalemic mixture enriched in crude (1S,4S,5R)-5-ethyl-2-oxabicyclo[2.2.1]heptan-3-one containing about 15 mol % TEA (0.912 g, 99%): 1H NMR (CDCl3) δ 4.85 (s, 1H), 2.88 (s, 1H), 2.19 (m, 2H), 2.08 (m, 1H), 1.69 (m, 1H), 1.41 (m, 3H), 0.97 (t, J=5.4, 3H).

Provenance & Evidence