4167-77-5

1. 1,4-dibromobutane and diethyl malonate are dissolved in DMF under nitrogen protection. 2. Potassium carbonate (K2CO3) and tetrabutylammonium fluoride (TBAF) were added sequentially to the above solution. 3. The reaction mixture was stirred at room temperature overnight. 4. 4. Upon completion of the reaction, the reaction was quenched with 200 mL of cold water. 5. The reaction mixture was extracted with a 10% ethyl acetate/hexane solvent mixture (3 x 150 mL). 6. The organic layers were combined and washed sequentially with half-saturated brine (150 mL x 2) and brine (150 mL). 7. The organic layer was dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated to dryness. 8. The residue was purified by fast silica gel column chromatography using 2% ethyl acetate/hexane as eluent to give 36.7 g (84% yield) of ethyl 1,1-dicarboxylate cyclopentane as a colorless oil.

[1] Tetrahedron Letters, 2005, vol. 46, # 4, p. 635 - 638
[2] Patent: WO2013/185202, 2013, A1. Location in patent: Paragraph 00280; 00281
[3] Patent: WO2015/95227, 2015, A2. Location in patent: Page/Page column 96; 97
[4] Journal of Medicinal Chemistry, 2018, vol. 61, # 3, p. 989 - 1000
[5] Journal of the American Chemical Society, 2010, vol. 132, # 41, p. 14409 - 14411