Ethyl 5-bromovalerate → HCID 11425452, compound

Participants

Reaction Steps

To a solution of 5.0 g (22.9 mmol) 1-oxo-1,2,3,4-tetrahydro-naphthalene-2-carboxylic acid ethyl ester (1a) (Pradeep, K., and Saravanan, K., Tetrahedron 54 (1998) 2161-2168) and 5.79 g ethyl-5-bromo-pentanoate (27.7 mmol) in 10 mL ethanol at reflux is added a freshly prepared solution of 0.53 g sodium in 15 mL ethanol. After 10 h at reflux enough water is added for the precipitate to dissolve. The solvent is evaporated, the residue is dissolved in a solution of 3.85 g KOH in 7 mL MeOH and 5 mL H2O and refluxed for another 10 h. After cooling the solution is poured into 25 mL ice-cold 4N HCl and extracted with CH2Cl2. Evaporation of the solvent leaves a residue of crude 5-(1-oxo-1,2,3,4-tetrahydro-naphthalen-2-yl)-pentanoic acid (1b) which is dissolved in 100 mL MeOH. A few drops of H2SO4 are added and the solution is refluxed over night. After addition of some sodiumbicarbonate-solution the solvent is evaporated and the residue is subjected to column-chromatography yielding 1.9 g methyl-(5-(1-oxo-1,2,3,4-tetrahydro-naphthalen-2-yl)-pentanoate) (1c). To a solution of 1.6 g (23 mmol) hydroxylamine hydrochloride in 40 mL MeOH is added 15 mL of a solution of 0.8 g (35 mmol) of sodium in 30 mL of MeOH. To this, a solution of 3.0 g (11.5 mmol) methyl-(5-(1-oxo-1,2,3,4-tetrahydro-naphthalen-2-yl)-pentanoate) (1c) in 20 mL MeOH is added, followed by the remaining 15 mL of the sodium methylate solution. After stirring for 6 h at rt the solvent is evaporated, acidified with 2N HCl and extracted with CH2Cl2. After evaporation the residue is purified by column-chromatography yielding 2.2 g of the title compound as an oil, MS (APCI): 260.1 (M−1).

Provenance & Evidence