Acetic Acid → (6R, 7S)-2,2-dimethyl-7-(1-methoxy-1-methylethyl)-1-aza-3-oxabicyclo[4.2.0]octan-8-one

Participants

Reaction Conditions

Reaction Steps

To a suspension of sodium hydride (38.1 mg, 50% in mineral oil) in N,N-dimethylformamide (1.14 ml) was added dropwise a solution of (6R, 7S)-2,2-dimethyl-7-(1-hydroxy-1-methylethyl)-1-aza-3-oxabicyclo[4.2.0]-octan-8-one (84.6 mg) in N,N-dimethylformamide (25.4 ml) at 0° C. After stirring for 30 minutes at 0° C., thereto was added a solution of dimethyl sulfate (75.13 μl) in N,N-dimethylformamide (0.676 ml), and the resultant mixture was stirred for 3 hours at 0° C. and for additional 1.5 hours at ambient temperature. Acetic acid (0.046 ml) was added to the mixture, and the solvent was distilled off in vacuo. The residue was diluted with ethyl acetate (20 ml) and then washed with an aqueous sodium chloride, 10% aqueous sodium bicarbonate, and a saturated aqueous sodium chloride in turn. The aqueous washings were extracted with ethyl acetate, and this extract was washed with an aqueous sodium chloride. The combined extracts were dried over magnesium sulfate, filtered and evaporated in vacuo. The residue (92.9 mg) was chromatographed on silica gel (2.5 g) eluting with a mixture of ethyl acetate and methylene chloride (1:100 to 1:3) to give (6R, 7S)-2,2-dimethyl-7-(1-methoxy-1-methylethyl)-1-aza-3-oxabicyclo[4.2.0]-octan-8-one (69.1 mg) as a pale yellow solid.

Provenance & Evidence