Citric Acid → (1S,2R)-1-(3-Fluorophenyl)-1,2-cyclopropanedimethanol

Participants

Reaction Conditions

Reaction Steps

(1S,5R)-1-(3-fluorophenyl)-3-oxabicyclo[3.1.0]hexan-2-one (4, 10.08 g, 0.052 mol, 1.0 equiv.) was dissolved in 2-methyl-THF (75.60 mL) under nitrogen. The solution was cooled to −5 to −10° C., and 2.0 M Lithium tetrahydroborate in THF (39.34 mL, 0.079 mol, 1.5 equiv.) was added to the reaction mixture while maintaining the internal temperature below 0° C. The reaction was stirred at 20-25° C. for 14-16 hours and monitored by HPLC and TLC (EtOAc/Heptane=1/1). Once the reaction was completed, the reaction mixture was cooled to 0-5° C. and reverse quenched into a pre-cooled (0-5° C.) 20% aqueous citric acid solution (50.40 mL, 1.67 equiv.) at such a rate as to maintain the internal temperature below 5° C. Once the quench was complete, the reaction mixture was warmed to 20-25° C. and stirred for at least 20 min. The aqueous layer was back extracted once with 2-methyl-THF (50.40 mL). The organic layers were combined and washed once with saturated aqueous sodium bicarbonate solution (20.16 mL) and once with 20% aqueous NaCl (20.16 mL). The solvent was removed under reduced pressure then azeotroped with 2-methyl-THF until KF is less than 1500 ppm to afford the title compound, ((1S,2R)-1-(3-fluorophenyl)cyclopropane-1,2-diyl)dimethanol; 5 (10.29 g).

Provenance & Evidence