Ethyl bromoacetate → (E)-6-[2-(2,6-Dichlorophenyl)ethenyl]-3,4,5,6-tetrahydro-4-hydroxy-4-methyl-2H-pyran-2-one

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Reaction Steps

A solution of 6-(2,4-dichlorophenyl)-2-oxo-5-hexene-4-yl acetate (1.3 g, 4.3 mmole) and ethyl bromoacetate (0.47 ml, 4.2 mmole) in dry THF (10 ml) was added dropwise to a vigorously stirred slurry of activated zinc dust (490 mg, 7.5 mmole), cuprous bromide (29 mg, 0.2 mmole), diethylaluminum chloride (25% solution in toluene; 1.72 ml, 4.3 mmole) and dry THF (5 ml) under N2 at 20° C. Stirring was continued for 5 hours before quenching with pyridine (3.5 ml). After the addition of water (50 ml) the mixture was extracted with ether (3×80 ml). The combined ether extracts were washed with 1N HCl (2×25 ml), H2O (2×50 ml) and brine, then dried (MgSO4), filtered and evaporated leaving the crude title compound as a pale yellow oil (1.2 g); pmr (CDCl3) δ1.28 (3H, t), 1.33 (3H, t), 2.10 (3H, s).

Provenance & Evidence