Allyl bromide → Ethyl 2-allyl-2-(diphenylmethyleneamino)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate

Participants

Reaction Conditions

Reaction Steps

A solution of ethyl 2-(diphenylmethyleneamino)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate (2.79 g, 6.21 mmol) in freshly distilled (THF 15 mL, 0.4 M) was cooled to −78° C. and treated with lithium bis(trimethylsilyl)amide (6.8 mL, 1.0 M in THF). After stirring for 10 min allyl bromide (2.25 g, 18.6 mmol) was added the reaction was warmed to room temperature and stirred for 16 h. After being complete by TLC, the reaction mixture was cooled to 0° C., diluted with ethyl acetate and washed successively with saturated aqueous NaHCO3 and saturated aqueous NaCl, dried over MgSO4, filtered and concentrated. Purification by MPLC (1-20% ethyl acetate in heptane with 0.5% triethylamine over 6 CV) gave ethyl 2-allyl-2-(diphenylmethyleneamino)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate as a colorless oil (1.81 g, 59%). Rf 0.52 (30% ethyl acetate in heptane); 1H NMR (CDCl3, 300 MHz) δ 7.58-7.53 (m, 2H), 7.39-7.22 (m, 6H), 7.16-7.12 (m, 2H), 5.89-5.74 (m, 1H), 5.07 (dd, J1=15.3 Hz, J2=2.1 Hz, 1H), 5.05 (dd, J1=8.7 Hz, J2=2.1 Hz, 1H), 3.70 (q, J=7.5 Hz, 1Hdiasterotopic), 3.69 (q, J=7.2 Hz, 1Hdiasterotopic), 2.70 (dd, J1=7.2 Hz, J2=1.2 Hz, 2H), 1.92-1.83 (m, 2H), 1.44-1.35 (m, 2H), 1.35-1.23 (m, 2H), 1.19 (s, 12H), 1.10 (t, J=7.2 Hz, 3H), 0.78 (t, J=6.6 Hz, 2H).

Provenance & Evidence