Trifluoromethanesulfonic acid → Ethyl 2-ethyl-4-(4-methoxybenzyloxy)cyclopentanecarboxylate

Participants

Reaction Conditions

Reaction Steps

To a mixture of ethyl 2-ethyl-4-hydroxycyclopentanecarboxylate (37.78 g, 203 mmol, Preparation #P.1) in DCM (100 mL) and cyclohexane (200 mL) at about 0° C. was added 4-methoxybenzyl 2,2,2-trichloroacetimidate (93.58 g, 331 mmol) followed by dropwise addition of trifluoromethanesulfonic acid (1.6 mL, 18.0 mmol) over about 35 min. The reaction mixture was stirred at about 0° C. for about 30 min. The ice bath was removed and the reaction mixture was stirred at ambient temperature for about 16 h. The suspension was poured into ice-water (500 mL) and stirred for about 30 min. The solid was removed by filtration while washing with DCM (100 mL). The layers in the filtrate were separated and the aqueous layer was extracted with DCM (3×200 mL). The combined organic layers were washed with water (200 mL), dried over anhydrous MgSO4, filtered, and concd under reduced pressure. The crude material was purified using silica gel chromatography eluting with a gradient of 0-100% DCM:EtOAc (95:5) in DCM to give ethyl 2-ethyl-4-(4-methoxybenzyloxy)cyclopentanecarboxylate (39.80 g, 64%): LC/MS (Table 1, Method b) Rt=2.90 min; MS m/z: 307 (M+H)+.

Provenance & Evidence