烯烴化合物是含碳碳雙鍵的一類化合物，因其雙鍵的不飽和性，可以發(fā)生多種類型的氧化或者還原反應(yīng)，構(gòu)建出各種其他官能團(tuán)，因而在有機(jī)化學(xué)中占有非常重要的地位，是合成各種化合物的重要中間體。
通過羥基消除制備烯烴
羥基消除制備烯烴是醇在酸性條件下經(jīng)過E1機(jī)理生成烯烴的消除。酸的作用是對(duì)羥基進(jìn)行質(zhì)子化生成好的離去基團(tuán)。
實(shí)例一
A solution of cyclohexanone (0.491 g,5 mmol) in 15 mL anhydrous THF was cooled to 0 ℃. Vinylmagnesium bromide (1.0 M in THF, 25 mL, 25 mmol) was then dropwise added, and the mixture was kept stirring for 2 h at 0 ℃.The reaction was quenched with saturated NH4Cl (30 mL), and the aqueous layer was extracted by ether (20 ml × 3). The combined organic layer was dried over anhydrous Na2SO4. The solvent was distilled under low pressure. The residue was purified by silica gel column chromatography (eluent: EtOAc/hexane = 1/40) to give colorless oil I (0.35g, 56% in yield). I dissolved in 10 mL dry benzene was refluxed for 2h in a Dean-Stark apparatus. In the presence of p-toluene sulfuric acid (30 mg, 0.174mmol). The residue was purified by silica gel column chromatography (eluent:hexane) to give P (colorlessliquid, 0.15 g, 50%in yield).
Reference: Journal of Medicinal Chemistry, 2012.55(2), 971-975.
實(shí)例二
A 250 mL round-bottom flask equipped with a magnetic stir bar was charged with ketone A (0.32 g, 1.0mmol) and 1 M anhydrous HCl in methanol (100 mL). The reaction progress was monitored by TLC. After 2h, the starting material had been consumed. The solution was neutralized with 1 M NaOH, diluted with ethyl acetate (100mL), and washed with water (3 x 50 mL). The combined organic layer was dried over MgSO4, filtered, and concentrated, furnishing 0.29 g (83%). Rf = 0.46 (50% ethyl acetate inhexane).
Reference: Organic Letters, 2012.14(2), 632-635.
來源：覽博網(wǎng)
