Diisopropylamine → 1-(4-Bromobutyl)cyclopentanecarboxylic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of diisopropylamine (150 mmol, 21 mL) in THF (100 mL) at −10° C. was added dropwise a 2.5M solution of n-butyl lithium in hexanes (145 mmol, 58 mL) while maintaining the temperature below 0° C. After the addition was complete, the solution was stirred for 30 min at 0° C., then it was cooled to −70° C. using a dry ice/acetone bath. A solution of methyl cyclopentanecarboxylate (100 mmol, 13.1 g) in THF (20 mL) was added dropwise at −70° C. maintaining the reaction temperature between −60 to −70° C. The mixture was then stirred for 1 h at −50 to −60° C. and a solution of 1,4-dibromobutane (100 mmol, 21.59 g) in THF (20 mL) was added dropwise and the light brown suspension was stirred for 1 h at −60 to −70° C. The cooling bath was removed and the reaction was allowed to equilibrate to room temperature and stirred overnight. The reaction mixture then was poured into a saturated solution of ammonium. chloride (200 mL) and the mixture was extracted with diethyl ether (2×100 mL). The combined extracts were washed with brine (150 mL), dried (MgSO4), filtered and the solution was concentrated under reduced pressure. The resulting residue was distilled at 120-133° C./2.5 mm Hg to obtain 12.8 g (48%) of 1-(4-bromobutyl)cyclopentanecarboxylic acid methyl ester as a colorless oil. HR MS: Obs. mass, 262.0565. Calcd. mass, 262.0568, (M+).

Provenance & Evidence