Hydrochloric Acid → 6-(Hydroxymethyl)-2H-1,4-benzoxazin-3(4H)-one

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Reaction Conditions

Reaction Steps

The mixture of 6.9 g of methyl 3-oxo-3,4-dihydro-2H-benzo[1,4]oxazine-6-carboxylate and 230 ml of tetrahydrofuran is cooled to −40° C. Over 30 minutes, 88.9 ml of diisobutylaluminium hydride (1.5M in toluene) are added dropwise at −40° C. The reaction mixture is stirred at from −40° C. to −20° C. over 1.5 hours and subsequently poured cautiously onto 150 ml of 2N HCl (cold). The organic phase is removed and the water phase extracted with tetrahydrofuran (5×100 ml). The organic phases are washed with brine (1×100 ml), filtered through cottonwool and concentrated by evaporation. The title compound is obtained as beige crystals from the residue by crystallization (from ethanol). Rf (2:1 EtOAc-heptane)=0.16; Rt=2.23; m.p.: 186-187° C.

Provenance & Evidence