1,3-Dibromopropane → Methyl (1R,4S)-1-(3-bromopropyl)-4-(2,5-dimethyl-1H-pyrrol-1-yl)cyclopent-2-ene-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of Example 1B (16.5 g, 74.4 mmol) in tetrahydrofuran (200 ml) was added dropwise lithium hexamethyl bis(trimethylsilyl)amide (1 M in tetrahydrofuran, 119 mL) at −50° C. The reaction mixture was stirred for 1 hour at the same temperature. 1,3-Dibromopropane (150 g, 744 mmol) was added dropwise over 1 hour. The reaction mixture was allowed to warm to −20° C. and stirred at the same temperature for 1 hour. LCMS showed that the reaction was complete. The reaction mixture was quenched with an aqueous ammonium chloride solution (6%, 600 mL), and extracted with ethyl acetate. The organic fraction was washed with aqueous ammonium chloride (6%), brine, dried with sodium sulfate, filtered, and concentrated in vacuo. The residue was purified by silica gel column chromatography (petroleum ether:ethyl acetate=80:1) to give Example 1C.

Provenance & Evidence