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Cyclohexyl magnesium bromide (Aldrich) in ether (2 M, 150 mL) was pumped under vacuum to remove ethyl ether, at rt, the residue obtained was then dissolved in anhydrous THF (100 mL) while cooled with an ice water bath. The solution was then added to a solution of diethyl oxalate (60 g ) in THF (150 mL) at -30--40° C. in 10 min. The reaction mixture was warmed to 0° C. for 5 min, and quenched with 10% HCl (100 mL), extracted with ethyl acetate (200 mL), the extract was washed with water (30 mL), brine (50 mL) and dried with sodium sulfate, then filtered. The filtrate was concentrated to give an oil. It was distilled 40-50° C. at 1 mm Hg to remove the starting material and the left over is the product (total of 46 g, 86% yield, purity >90%, it can be distilled at 1 mm Hg, 75-80° C.). 1H NMR δ: 1.20-1.40 (m, 8H), 1.62-1.94 (m, 5H), 3.02 (broad s, 1H), 4.30 (q, J=8 Hz, 2H). 13C-NMR δ 13.91, 25.11, 25.58, 27.36, 46.13, 62.07, 161.84, 197.51.

1. customto remove ethyl ether
2. customat rt, the residue obtained
3. temperaturewhile cooled with an ice water bath
4. customquenched with 10% HCl (100 mL)
5. extractionextracted with ethyl acetate (200 mL)
6. washthe extract was washed with water (30 mL), brine (50 mL)
7. dry with materialdried with sodium sulfate
8. filtrationfiltered
9. concentrationThe filtrate was concentrated
10. customto give an oil
11. distillationIt was distilled 40-50° C. at 1 mm Hg
12. customto remove the starting material
13. waitthe left
14. distillationthe product (total of 46 g, 86% yield, purity >90%, it can be distilled at 1 mm Hg, 75-80° C.)