was added the reaction was refluxed for 20 hours and then cooled to room temperature and filtered nabr the mother liquor was collected and concentrated in vacuo to a yellow oil the crude product was then distilled under vacuum 197 u00b0 c to afford 15 2 g 53 of pure product to a stirring solution of methyl diethylmalonate 17 4 g 100 mmol in thf 200 ml 0 5 m was added sodium hydride 2 4 g 100 mmol the solution began bubbling and an exothermic reaction occurred the reaction eventually turned clear and then pentyl bromide 12 4 ml 100 mmol was added the reaction was refluxed for 20 hours and then cooled to room temperature and filtered nabr the mother liquor was collected and concentrated in vacuo to a yellow oil the crude product was then distilled under vacuum 160 u00b0 c to afford 12 1 g 50 of pure product to a stirring mixture of dipentyl diethylmalonate 9 0 g 30 mmol in water 60 ml and ethanol 60 ml was added koh pellets 16 8 g 300 mmol the cloudy mixture was then refluxed overnight where it became clear the solvent was concentrated in vacuo to a white solid the solid was dissolved in water and extracted with ether 2 u00d7 the water layer was then acidified with concentrated hcl and a solid precipitated out of solution the white solid was filtered and the resulting mother liquor was extracted with ether in order to isolate.