Phthalic Anhydride → 2-(3-(Tert-butoxycarbonyl)phenyl)-3-methylpyridine 1-oxide

Participants

Reaction Conditions

Reaction Steps

tert-Butyl-3-(3-methylpyridin-2-yl)benzoate (1.0 eq) was dissolved in EtOAc (6 vol). Water (0.3 vol) was added, followed by urea-hydrogen peroxide (3 eq). Phthalic anhydride (3 eq) was then added portionwise to the mixture as a solid at a rate to maintain the temperature in the reactor below 45° C. After completion of the phthalic anhydride addition, the mixture was heated to 45° C. After stirring for an additional 4 hours, the heat was turned off. 10% w/w aqueous Na2SO3 (1.5 eq) was added via addition funnel. After completion of Na2SO3 addition, the mixture was stirred for an additional 30 minutes, and the layers separated. The organic layer was stirred, and 10% wt/wt aqueous. Na2CO3 (2 eq) was added. After stirring for 30 minutes, the layers were allowed to separate. The organic phase was washed 13% w/v aq NaCl. The organic phase was then filtered and concentrated to afford crude 2-(3-(tert-butoxycarbonyl)phenyl)-3-methylpyridine-1-oxide (95%) that was used directly in the next step.

Provenance & Evidence