Bromine → Ethyl 5-oxocyclopent-1-ene-1-heptanoate

Participants

Reaction Steps

Under agitation at 20° , 48 g. of Br2, dissolved in 500 ml. of CHCl3, is added dropwise within 2 hours to a solution of 100 g. of 2-carbethoxy-2-(6-carbethoxyhexyl)-cyclopentanone in 1 l. of CHCl3. The solvent is distilled off, the residue is taken up in a mixture of 4 l. of ethanol, l kg. of H2SO4 (density: 1.84), and 100 ml. of H2O, refluxed for 18 hours under N2 and poured on 10 kg. of ice after cooling. The reaction mixture is extracted three times with respectively 5 l. of ether, the combined ether extracts are dried over Na2SO4, the solvent is distilled off, and chromatographic purification of the residue (silica gel/petroleum ether : ether =1 : 1) yields 2-(6-carbethoxyhexyl)- 2-cyclopentenone.

Provenance & Evidence