邻位碳上有氢原子的脂肪烃是很容易发生β消除生成烯烃的，如果用一级碱来消除会伴随取代反应的副产物，这种情况用高位阻的碱能提高消除产率。(P. Veeragu, R. T. Arnold, and E. W. Eigemann, J. Am. Chem. Soc., 86, 3072 (1964); R. A. Bartsch and J. F. Bunnett, J. Am. Chem. Soc., 90, 408 (1968).)

实例一

Amixture of 0.4 g (0.8 mmol) of compound Aand 2 ml of piperidine was heated for 10 h at 110°C. The solvent was distilledoff under reduced pressure, the residue was dissolved in 50 ml of methylenechloride, the solution was washed with water and dried over MgSO₄, the solvent was removed, and the residue was crystallized from ethanol to give P 0.28 g.

Reference: Russ.J.Org.Chem, 2012, 48, 957-967.

实例二

DibromideI, 5.0 g (18 mmol), was added to a solution of 0.99 g (43 mmol) of metallic sodium in 70 ml of ethanol. The mixture was heated for 1 h under reflux, the solvent was removed under reduced pressure, and the residue was treated with250 ml of water and extracted with ethyl acetate. The extract was dried overanhydrous Na₂SO₄, filtered, and evaporated under reduced pressure, and the residue was distilled in a vacuum. Yield 54%, colorless transparent viscous liquid. bp 70-90°C (4 mm).

Reference: Russ.J.Org.Chem, 2013, 49, 1329-1334.

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