Ammonium Chloride → Ethyl 2-ethyl-4-hydroxycyclopentanecarboxylate

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Reaction Steps

To ethyl 2-ethyl-4-oxocyclopentanecarboxylate (10 g, 54.3 mmol, Example #8, Step G) in MeOH (143 mL) was added NaBH4 (2.57 g, 67.8 mmol) portionwise. The resulting suspension was stirred for about 16 h at ambient temperature then saturated aqueous NH4Cl (240 mL) was added. The reaction mixture was stirred for about 20 min then the solution was partitioned with Et2O (300 mL). The organic layer was separated and the aqueous layer was washed with Et2O (2×150 mL). The combined organic layers were washed with brine (100 mL), dried over anhydrous MgSO4, filtered, and concd under reduced pressure. The product was purified by silica gel chromatography (220 g) eluting with a gradient of 30-70% EtOAc in heptane to give ethyl 2-ethyl-4-hydroxycyclopentanecarboxylate (8.51 g, 84%, predominantly (1S,2R,4S)-ethyl 2-ethyl-4-hydroxycyclopentanecarboxylate and (1R,2S,4R)-ethyl 2-ethyl-4-hydroxycyclopentanecarboxylate) as a clear oil: LC/MS (Table 1, Method b) Rt=2.02 min; MS m/z: 187 (M+H)+.

Provenance & Evidence