N-[1-(3,4-dichlorophenyl)ethylidene]hydroxylamine → [3-(3,4-Dichloro-phenyl)-isoxazol-5-yl]-acetic acid ethyl ester

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Reaction Steps

To a solution of ethyl 2,3-butadienoate (1 eq) and 1-(3,4-dichloro-phenyl)-ethanone oxime (1.03 eq) in DCM (51 vol) was added a 10% aqueous bleach solution (51 vol) and the resultant biphasic system stirred at room temperature for 5 days. The organic layer was separated and the aqueous layer extracted with DCM (3×7 vol). The combined organic layers were washed with water (36 vol), dried over MgSO4, filtered and concentrated. The crude residue was purified by a combination of flash column chromatography (eluent: [0:1 to 1:2] EtOAc:heptane) and prep HPLC to yield [3-(3,4-Dichloro-phenyl)-isoxazol-5-yl]-acetic acid ethyl ester.

Provenance & Evidence