Ethyl Bromide → (2,4Dichlorophenyl)-2-buten-1,4-diol

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A suspension under nitrogen of magnesium (0.8 g; 32.7 mmoles) in ethyl ether (17 ml) kept at 20° C. under stirring, was added with ethyl bromide (25 mg). After 15 minutes a solution of 1,3-dichloro4-iodobenzene (5.95 g; 21.8 mmoles) and ethyl bromide (25 mg) in dry ether (13 ml) was dropwise added (about 1 hour) keeping the temperature at 15-20° C. At the end of the dropping the suspension was kept at 15-20° C. for 2 hours more. The magnesium in excess was removed and the obtained solution was dropped, keeping the temperature at 0-5° C., in a second flask containing a suspension formerly prepared. Such suspension was obtained by adding, at 0-5° C., a THF solution of 3M methyl magnesium chloride (9.6 ml; 29 mmoles) to a solution of 2-butin-1,4-diol (1.25 g; 14.5 mmoles) in THF (30 ml). At the end of the addition the suspension was refluxed and stirred at mild reflux for 24 hours. After cooling to 0° C., an aqueous solution of saturated NH4Cl was added, the phases were divided and the aqueous one extracted in ether (30 ml). The joined organic phases were washed with water (30 ml), anhydrified over dry Na2SO4, dried. The product was purified by flash chromatography (SiO2; petrolatum/ethyl acetate 60/40) to give 0.24 g of (E) (2,4dichlorophenyl)-2-buten-1,4-diol (yield 7,3%). The 1H-NMR effected on the product is practically the same of the one reported in example 4.

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