O-Methylhydroxylamine hydrochloride → N-Benzyloxycarbonyl-2(R,S)-methoxyiminomethyl-3,4-dihydro-2H-1,4-benzoxazine

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Reaction Steps

3.42 g of O-methylhydroxylamine hydrochloride are added to a solution of 600 mg of N-benzyloxycarbonyl-2(R,S)-formyl-3,4-dihydro-2H-1,4-benzoxazine (Rf =0.31; prepared by means of Swern oxidation (Example 1g) from Example 87c) in 30 ml of pyridine and the reaction mixture is then stirred at room temperature for 36 h and subsequently concentrated. The crude product is dissolved in ethyl acetate and the solution is washed with a 1N sodium bicarbonate solution, water and saturated sodium chloride solution. N-Benzyloxycarbonyl-2(R,S)-methoxyiminomethyl-3,4-dihydro-2H-1,4-benzoxazine is obtained (540 mg): Rf (A)=0.61. A further reaction analogously to Example 87a) and purification of the crude product by means of FC over 50 g of silica gel (mobile phase N) gives 2(R,S)-methoxyiminomethyl-3,4-dihydro-2H-1,4-benzoxazine: Rf (A)=0.51.

Provenance & Evidence