Acetamide → Ethyl 2-fluorooctanoate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

--A mixture of acetamide (49 g) and ethyl 2-bromooctanoate 64 (100 ml, 0.464 mol) was heated at 80° C. (reaction temperature) with mechanical stirring under nitrogen until homogeneous. Anhydrous potassium fluoride (49.3 g, 0.84 mol) was added followed by tetrabutylammonium fluoride (3.25 ml). The mixture was heated for 5 h at 140° C. with rapid stirring and allowed to cool to 90° C. prior to pouring into ice (400 ml). The reaction vessel was rinsed with water and dichloromethane which were added to the ice mixture. The aqueous phase was extracted with dichloromethane (3 times); the combined organic solutions were dried (Na2SO4) and filtered. The solution was cooled to 5° C. under nitrogen and bromine (19.3 ml, 0.375 mol) was added. After 3 h saturated sodium thiosulfate solution (150 ml) was added. The organic phase was washed with sat. sodium bicarbonate solution (twice) and brine, dried (Na2SO4) and evaporated. The residue was distilled to give pure ethyl 2-fluorooctanoate 65 (33.9 g, 38%); b.p. 56-61° C. at 0.5 mm Hg; νmax /cm-1 (film) 2930, 2860, 1760, 1740, 1370, 1275, 1205, 1090 and 1030; δ 0.88 (3H, t, Me), 1.20-1.56 (11H, m), 1.75-2.13 (2H, m), 4.26 (2H, q, ) and 4.90(1H, 2JHF 46 and J8, CHF); m/z 190 (M+), 185, 168, 161, 143, 129, 113 and 106.

Herkunft & Nachweise