Diisobutylaluminumhydride → HCID 71437553, compound

Participants

Reaction Steps

To a stirring, cold (−10° C.) solution of ethyl 4-(tert-butoxycarbonylamino)-2-fluorobut-2-enoate (a 10:1 mixture of EIZ isomers; 6.33 g, 25.6 mmol) in CH2Cl2 (200 mL) under Ar was added dropwise Diisobutylaluminium hydride solution (1M solution in hexanes, 70.5 mL, 70.49 mmol). After addition was complete the reaction was left to stir at this temperature for a further 2 h. The reaction was then quenched carefully by dropwise addition of cold water. The resulting slurry was poured into a flask containing a saturated aqueous solution of sodium potassium tartrate (400 mL) and the biphasic mixture was stirred vigorously for 2 h. After transferring the mixture to a separatory funnel the aqueous phase was extracted with CH2Cl2 (3×100 mL). The combined organics were washed with brine (100 mL), dried over anhydrous MgSO4 and concentrated in vacuo to give tert-butyl-3-fluoro-4-hydroxybut-2-enylcarbamate as a 10:1 mixture of E/Z isomers. Purification and separation of the desired E isomer was performed using silica gel chromatography eluting with 30% ethyl acetate in hexanes affording (E)-tert butyl-3-fluoro-4-hydroxybut-2-enylcarbamate (4.25 g, 20.7 mmol, 81%) as a colourless oil that solidified upon cooling, 1H-NMR (200 MHz, CDCl3): δppm: 1.43 (9H, s), 3.72 (2H, dd, J 7.5, 5.4 Hz), 4.25 (2H, d, J 21.5 Hz), 4.85 (1H, br s), 5.18 (1H, dt, 19.2, 8.5 Hz).

Provenance & Evidence