Methanesulfonic Acid → 8-tert-Butyl-3,4-dihydro-2H-benzo[f][1,4]oxazepin-5-one

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Reaction Conditions

Reaction Steps

7-tert-Butyl-chroman-4-one (1.3 g, 6.36 mmol) was taken up in dichloromethane (11.25 mL) and methane sulfonic acid (7.5 mL) and cooled to 0° C. With stirring at 0° C. was added sodium azide (827 mg, 2 eq) portion-wise. The resulting mixture was stirred at 0° C. for 3 hours and by TLC analysis there was no more starting material remaining, so the reaction mixture was poured into a 20% solution of NaOH(aq) (25 mL) at 0° C. This solution was stirred for 10 minutes and then it was extracted with dichloromethane (3×50 mL) and the combined dichloromethane layers were washed with brine (1×50 mL). The organic layer was dried over magnesium sulfate, filtered and concentrated. Purification by column chromatography on silica gel eluting with a gradient of 5% ethyl acetate in hexanes to 100% ethyl acetate afforded the title compound as a white solid (1.304 ) (M+H)+=220.

Provenance & Evidence