3,4-dihydro-2H-pyran → 6-(Tetrahydropyran-2-yloxymethyl)-4H-benzo[1,4]oxazin-3-one

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Reaction Steps

The solution of 5.0 g of 6-hydroxymethyl-4H-benzo[1,4]oxazin-3-one in 60 ml of dichloromethane is admixed successively with 5.20 ml of 3,4-dihydro-2H-pyran and 0.236 g of p-toluenesulphonic acid monohydrate. The reaction mixture is stirred at room temperature over 14 hours. The solution is poured onto 1M sodium hydrogencarbonate solution (300 ml) and extracted with tert-butyl methyl ether (2×400 ml). The organic phase is washed with brine (300 ml), dried over sodium sulphate, filtered and concentrated by evaporation. The title compound is obtained as a beige solid from the residue by means of crystallization (EtOAc/heptane). Rf=025 (1:1 EtOAc-heptane); Rt=3.45.

Provenance & Evidence