2,2'-Bipyridine → Ethyl 4,4-dimethyl-3-oxohex-5-enoate

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Reaction Steps

Monoethyl hydrogen malonate (7.2 g, 0.05 mol) and bipyridyl (few milligrams) were dissolved in THF (90 ml) and the system was flushed with nitrogen. The solution was cooled to −70°, then BuLi (2.5 M in hexanes, 37 ml, 0.09 mol) was added. After the addition of only ˜10 ml of BuLi the solution turned pink and additional THF (15 ml) was required to enable magnetic stiffing. The cooling bath was removed and the remaining BuLi was added, the temperature was allowed to reach −10°, upon which the solution turned colorless. The mixture was again cooled to −60° and a solution of 2,2-dimethyl-but-3-enoyl chloride (4.1 g, 0.03 mol) in THF (12 ml) was added dropwise. After addition was complete the mixture was allowed to warm to 0° and stir for 3 h, then it was added to a 1:1 mixture of ether/1M HCl (260 ml) at 0° and stirred for a further 1.5 h. The organic layer was removed, washed with HCl (1 M), sodium bicarbonate solution, brine then dried and evaporated to give 4,4-dimethyl-3-oxo-hex-5-enoic acid ethyl ester (5.6 g, 98%). (Hayashi et al., J. Org. Chem., 65:8402-8405 (2000). Distillation with a Kugelrohr oven (160°/1 mmHg) afforded pure material.

Provenance & Evidence