Boron trifluoride etherate → HCID 57889867, compound

Participants

Reaction Conditions

Reaction Steps

A 50 mL three neck round bottom flask equipped with a magnetic stirrer and two addition funnels, which had been flame dried under argon, charged with COPPER(I) CYANIDE (226 mg, 2.52 mmol), and evacuated under high vacuum overnight, was charged with THF (5 mL), and the suspension was cooled to −78° C. The mixture was treated with the dropwise addition of methyllithium (1.6 M in diethylether) (3.15 mL, 5.04 mmol). When the addition was complete, the cooling bath was removed, and the suspension was allowed to slowly warm, until a homogeneous solution was observed. The solution was cooled to −78° C., then treated with the slow dropwise addition of a solution of trans-benzyl 6-oxabicyclo[3.1.0]hexane-3-carboxylate (250 mg, 1.145 mmol) in THF (5 mL) followed by boron trifluoride etherate (0.581 mL, 4.58 mmol) in one portion. The mixture was stirred at −78° C. for 2 h, at which point a precipitate was observed, and the color quickly changed to bright yellow. The reaction was allowed to slowly come to room temperature, during which the color began to turn grey. The reaction was quenched with 30 mL of a 9:1 aqueous solution of saturated NH4Cl and 10% NH4OH, and the mixture was stirred for 30 minutes. The resulting deep blue mixture was filtered to remove a small amount of precipitate, and extracted 3× with ethyl acetate. The combined organic phases were washed with water followed by brine, then dried over sodium sulfate and concentrated in-vacuo. The residue was purified over a 2×15 cm silica gel column, eluting with ethyl acetate/hexanes (25%-50% EtOAc), to yield a racemic mixture of (1R,3R,4R)-benzyl 3-hydroxy-4-methylcyclopentanecarboxylate and (1S,3S,4S)-benzyl 3-hydroxy-4-methylcyclopentanecarboxylate (225 mg, 0.480 mmol, 84% yield) as a colorless oil.

Provenance & Evidence