Dibah → HCID 59440099, compound

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of the methyl ester 5 (4.4 g, 9.5 mmol) in anhydrous dichloromethane (11 mL) and toluene (33 mL) was added dibal-H (19 mL, 1.0 M in toluene) dropwise via a syringe pump in 30 minutes at −78° C. The mixture continued to be stirred at −78° C. for 3 hours and TLC (hexanes/AcOEt, 1:1.5) showed that the starting material was almost consumed. The reaction was quenched with methanol (0.4 mL) and 5% HCl (30 mL) at −78° C. Ethyl acetate (100 mL) was added and the dry ice/acetone bath was removed. The mixture was stirred at room temperature for 30 minutes and then transferred to a separatory funnel. The aqueous layer was extracted with AcOEt twice and the combined organic layers were washed with brine, saturated sodium bicarbonate and brine, and dried over anhydrous sodium sulfate. It was filtered through celite and the solvents were removed under reduced pressure (temperature <35° C.). The residue was purified by flash chromatography (Hexanes/AcOEt, 1.5:1, 1:1, 1:1.5) to give the aldehyde 6 as a yellow solid (2.85 g, y=69%). 1H NMR (400 Hz, CDCl3): the compound appears as three distinct rotomers. δ 10.02 (s, 0.3H), 9.85 (s, 0.5H), 9.45 (s, 0.2H), 8.32-8.31 (m, 0.2H), 7.93 (s, 0.3H), 7.83 (s, 0.5H), 7.79 (s, 0.2H), 7.53-7.34 (m, 5.2H), 7.26-7.14 (m, 1.3H), 7.08 (s, 0.5H), 7.01-6.94 (m, 1H), 6.91-6.82 (m, 1H), 5.78 (d, J=8.4 Hz, 0.3H), 5.71 (d, J=8.4 Hz, 0.5H), 5.52-5.48 (m, 0.5H), 5.35-5.21 (m, 2.3H), 4.53-4.50 (m, 0.2H), 4.06 (s, 1.5H), 3.98 (s, 0.6H), 3.94 (s, 0.9H), 3.63-3.17 (m, 2H); HRMS (ESI, m/z): calc. 433.1400 (M+H)+. found 433.1387.

Provenance & Evidence