Triethylborane → 2-(2-Morpholin-4-yl-2-oxo-ethyl)-2-(3-phenyl-allyl)-malonic acid diethyl ester

Participants

Reaction Steps

Triethylborane (1.0 M in THF, 149.5 ml, 149.5 mmol) was added to oxazole (10.33 g, 149.5 mmol) and stirred for 45 minutes at room temperature. The mixture was then cooled to −78° C. and n-BuLi (2.5 M in hexane, 59.8 ml, 149.5 mmol) was added dropwise and allowed to stir for one hour under nitrogen. Compound (1) (8.0 g, 42.7 mmol) was dissolved in 25 ml of THF and added to the reaction mixture. The reaction was stirred for 5 hours at −78° C. then it was allowed to warm to 0° C. for one hour. The reaction was then cooled back to −78° C. and quenched with 7% acetic acid in ethanol (700 ml) which was allowed to stir overnight at room temperature. The mixture was concentrated in vacuum and the residue was dissolved in ether and filtered. The filtrate was concentrated in vacuum and the residue was dissolved in ethyl acetate washed twice with 0.005 N HCl, twice with saturated sodium bicarbonate and brine. The organic layer was dried over magnesium sulfate, filtered and concentrated in vacuum. The residue was purified on silica using 10–40% ethyl acetate/heptane to give [(S)-1-(Hydroxy-oxazol-2-yl-methyl)-propyl]-carbamic acid tert-butyl ester ((2), 3.85 g).

Provenance & Evidence