Water → Tert-butyl 2-(2-(4-chlorophenoxy)ethyl)-2-(diphenylmethyleneamino)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate

Participants

Reaction Steps

While under a nitrogen atmosphere, a solution of tert-butyl 4-(4-chlorophenoxy)-2-(diphenylmethyleneamino)butanoate (450 mg, 1.0 mmol) in tetrahydrofuran (7 mL) was cooled to −78° C. and treated with sodium bis(trimethylsilyl)amide (2.0 mL, 1.0 M in tetrahydrofuran, 2.0 mmol) in a dropwise manner. After the addition was complete, stirring was continued for 30 minutes and 2-(4-iodobutyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (931 mg, 3.0 mmol) was slowly added to the reaction mixture. Stirring was continued for 2 more hours, and then slowly warmed to room temperature overnight. The resulting solution was poured into water, and extracted with ethyl acetate (3×). The combined organic phase was washed with saturated aqueous sodium chloride, dried over anhydrous magnesium sulfate, filtered and concentrated. Purification by flash column chromatography (silica gel, 0-15% ethyl acetate in heptane) gave tert-butyl 2-(2-(4-chlorophenoxy)ethyl)-2-(diphenylmethyleneamino)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate as a colorless oil (486 mg. 77%); 1H NMR (CDCl3, 300 MHz) δH 7.54 (d, J=7 Hz, 2H), 7.36 (m, 4H), 7.18-7.32 (m, 6H), 6.82 (d, J=9 Hz, 2H), 4.19 (m, 1H), 4.04 (m, 1H), 2.39 (ddd, J=14 Hz, J2=9.5 Hz, J3=5.0 Hz, 1H), 2.22 (ddd, J1=13.5 Hz, J2=9.5 Hz, J3=5.0 Hz, 1H), 1.73 (m, 2H), 1.14-1.46 (m, 4H), 1.34 (s, 9H), 1.18 (s, 12H) and 0.76 (t, J=7 Hz, 2H); MS (+CI): m/z for C37H47BClNO5: expected 631.3. found 632.3 (M+H)+, 576.3 (M+H-isobutene)+.

Provenance & Evidence