Trifluoromethanesulfonic anhydride → (S)-3-(4-chloro-5-fluoroindolin-1-yl)dihydrofuran-2(3H)-one

Participants

Reaction Conditions

Reaction Steps

Prepared using general procedure 1. Under an N2 atmosphere at −40° C., N,N-diisopropylethylamine (34.1 mL, 196 mmol) was added dropwise to a solution of (R)-dihydro-3-hydroxyfuran-2(3H)-one (10.0 g, 98 mmol) in CH2Cl2 (100 mL). Trifluoromethanesulfonic anhydride (17.3 mL, 103 mmol) was added dropwise to this solution maintaining the internal temperature of the reaction mixture below −40° C. Upon completion of addition, the mixture was stirred at −40° C. for 1 h. A solution of 4-chloro-5-fluoroindoline (27.6, 147 mmol) in CH2Cl2 (40 mL) was added dropwise to this solution maintaining the internal temperature of the reaction mixture below −40° C. The reaction was allowed to warm up to −20° C. and was kept at this temperature for 48 h. The reaction mixture was washed with saturated aqueous sodium bicarbonate (2×), brine, dried over magnesium sulfate, and concentrated. Purification via silica gel chromatography using 0-40% ethyl acetate in hexane gave (S)-3-(4-chloro-5-fluoroindolin-1-yl)-dihydrofuran-2(3H)-one as a white solid (22.9 g, 90%). 1H NMR (400 MHz, DMSO-d6) δ 7.07-7.02 (m, 1H), 6.50 (dd, J=3.6, 8.6 Hz, 1H), 4.88 (dd, J=9.0, 11.4 Hz, 1H), 4.44-4.39 (m, 1H), 4.29-4.22 (m, 1H), 3.60-3.54 (m, 1H), 3.28 (dd, J=8.6, 17.8 Hz, 1H), 3.07-2.92 (m, 2H), 2.43-2.28 (m, 2H). LC/MS (10%-99% CH3CN (0.035% TFA)/H2O (0.05% TFA)), m/z: M+1 obs=256.1; tR1.54 min.

Provenance & Evidence