Nitric Acid → Nitro-oxazine

Participants

Reaction Conditions

Reaction Steps

The oxazine of formula XI (0.1 mmol) was added portionwise to concentrated sulfuric acid (2 ml) at 22° C. The solution obtained was cooled to 0° C. and treated with red fuming nitric acid (0.058 ml) and stirring was continued at 0° C. for 2 hours. For the workup, the reaction mixture was slowly added to crushed ice and the pH was adjusted to 10 using a saturated solution of sodium carbonate. The aqueous layer was extracted with ethyl acetate, the organic layer was dried over sodium sulphate and evaporated to afford the pure nitro-oxazine of formula XII. Alternatively, the crude product was purified by flash chromatography on silica-NH2 gel using mixtures of heptane or cyclohexane and ethyl acetate as the eluent to yield the pure nitro-oxazines of formula XII.

Provenance & Evidence