烯丙醇选择性去氧还原、异构化和分子内环化反应研究

【作者】 王家亮；

【导师】 周锡庚；

【作者基本信息】 复旦大学 ， 有机化学， 2009， 博士

【摘要】 羟基是有机分子中常见的官能团之一,羟基的选择性还原和转化是有机合成过程中经常需要涉及的反应。针对该研究领域的发展趋势和新的应用需求,本论文主要探索了烯丙醇的选择性还原、异构化和分子内Friedel-Crafts反应,取得了一些有学术价值和潜在应用价值的新成果。具体如下:第一部分:研究了金属-SiCl₄体系促进的烯丙醇去氧偶联反应。我们发现Dy-SiCl₄可以促进烯丙醇发生去氧偶联反应,以中等到优秀的收率得到偶联产物。通过验证实验,提出了该反应的可能机理。进一步研究发现Fe-SiCl₄体系也能促进烯丙醇去氧偶联反应。后者的优点是不需要添加剂,条件更温和,且反应选择性更高。但是,相同条件下,Sm-SiCl₄和Zn-SiCl₄对该去氧偶联反应表现出较低的活性。第二部分:研究了FeCl₃·6H₂O催化的醇歧化反应及烯丙醇和烯丙醇衍生物的选择性烯丙基还原。研究结果表明FeCl₃·6H₂O不仅可以催化烯丙醇歧化得到查尔酮和烯烃,还可以催化不同醇（如烯丙醇和苄醇）间的交叉歧化反应。利用该反应原理,我们发展一种操作简便、经济的用苯甲醇选择性还原烯丙醇、烯丙基醚和烯丙基酯的新方法。深入研究结果显示,其它苄醇（如对硝基苯甲醇和对甲氧基苯甲醇）和硅氢烷也可以作为烯丙基还原反应的还原剂。最后,通过同位素跟踪实验,提出了FeCl₃催化的烯丙醇去氧还原反应的可能机理。第三部分:研究了FeCl₃·6H₂O催化芳基取代烯丙醇分子内环化反应。芳基取代烯丙醇经历分子内Friedel-Crafts化反应形成茚通常需要强酸性介质或过量Lewis酸催化剂,在深入研究铁催化的烯醇转化反应中,我们观察到FeCl₃·6H₂O可以高效高选择性地催化芳基取代烯丙醇发生分子内Friedel-Crafts化反应,生成取代茚,反应在非配位性溶剂中的活性较配位性溶剂中高。值得一提的是,与前期文献报道结果不同,在当前的催化体系下,不管烯丙醇1-位和3-位芳环的亲核性质有何差别,亲电进攻都优先由含取代基较少的碳原子承担,即烯丙基阳离子中间体均趋向于异构到取代基较少的一端进行分子内Friedel-Crafts反应。第四部分:研究了BuLi促进的烯丙醇异构化反应及其在有机合成中的应用。阐明了丁基锂与烯丙醇反应,能形成稳定的碳氧双锂盐,并对其进行了晶体结构表征。重水水解该双锂盐则可以实现从烯丙醇合成α,β-二氘代酮。进一步,我们研究了碳氧双锂盐与三甲基氯硅烷的反应,反应可以有效生成烯丙氧基硅烷和3-三甲基硅基烯醇硅醚。更多还原

【Abstract】 This thesis focuses on the redox reaction of allylic alcohols:We have demonstrated M-SiCl₄ promoted deoxygenative coupling of allylic alcohols,which further enriched the application of dysprosium in organic synthesis.We have established iron salt catalyzed disproportionation and cyclization of allylic alcohols.We successfully applied disproportionation to selective deoxygenation of allylic alcohols and allylic derivatives with benzyl alcohol.We have developed a method for the synthesis of dilithio reagent from allylic alcohol.The structure of the dilithio intermediate was verified by X-ray.The whole thesis is divided into four chapters,the details are as follows:Chapter 1:Investigation of the deoxygenative coupling of allylic alcohols promoted by metal-SiCl₄.At first,we observed that Dy-SiCl₄ promoted the deoxygenative coupling of allylic alcohols.The deoxygenative coupling products were obtained in moderate to high yields,when various allylic alcohols were used as substrates. Tetrakis（1,3-diphenylallyl）siloxane and 1,3-diphenylallyl chloride,which could be formed in the process,reacted with Dy-SiCl₄ giving coupling products in 85%and 84%yield respectively.When PhCHCHCH（OD）Ph was used as substrate,the reduction of product included the deuterium atom in the allyl position.On the basis of these results,we proposed the plausible mechanism of Dy-SiCl₄ promoted deoxygenative coupling of allylic alcohols.We found that Fe-SiCl₄ could also efficiently promote the deoxygenative coupling of allylic alcohols without an additive under mild reaction conditions.However,Sm-SiCl₄ and Zn-SiCl₄ exhibited much lower activities in the same conditions.Chapter 2:FeCl₃·6H₂O catalyzed the disproportionation of allylic alcohols and selective allylic reduction of allylic alcohols and their derivatives with benzyl alcohol. We observed that FeCl₃·6H₂O not only catalyzed the disproportionation of allylic alcohol yielding alkene and chalcone,but also catalyzed cross disproportionation of two different alcohols（allylic alcohol and benzyl alcohol） giving alkene and benzaldehyde.The yield of deoxygenation of allylic alcohol depended on the stoichiometric ratio of allylic alcohol and benzyl alcohol,and the best result was achieved in neat benzyl alcohol.Other benzyl alcohols and triethylsilane also worked as reducing agents,but alkyl alcohols（such as:ethanol and 2-propanol） were not effective.We successfully applied this reaction to selective allylic reduction of allylic alcohols,allylic acetates and allylic ethers with benzyl alcohol.On the basis of deuterium isotope-labeling experiments,the plausible mechanism was proposed for the FeCl₃-catalyzed allylic reduction of allylic alcohols with benzyl alcohol.Chapter 3:An efficient procedure for the synthesis of substituted indenes through the FeCl₃·6H₂O catalyzed intramolecular Friedel-Crafts cyclization of aryl-substituted allylic alcohols have been developed.Although it has proved successful for aryl-substituted allylic alcohols to serve as precursors for the synthesis of indenes via the intramolecular Friedel-Crafts reactions,in most cases a strong acidic medium and/or an excess amount of Lewis acid promoter were required.Considering cost and environment factors,we tried to use catalytic amount of FeCl₃·6H₂O to catalyze the cyclization of allylic alcohols.The results showed that the strategy was feasible. Screening of the other iron salts revealed that Fe（acac）₃,Fe（NH₄）（SO₄）₂·12H₂O, FeCl₂·6H₂O and Fe（AcO）₂ were inefficient for the cyclization of allylic alcohols except anhydrous FeCl₃.Subsequently,we studied the scope of the reaction.The results indicated that tertiary allylic alcohols can easily undergo the cyclization to afford indene derivatives through isomerization/cyclization in the catalytic amount of FeCl₂·6H₂O.Secondary allylic alcohols including a substituent at the 2-position of allylic alcohols can also undergo the intramolecular Friedel-Crafts reaction.Chapter 4:Synthesis of dilithio reagents via isomerization of allylic alcohols promoted by BuLi:Structural characterization of the dianion intermediate and its application in organic synthesis.We observed that reaction of allylic alcohols with butyl lithium can form the stable intermediate due to releasing butane in the process. We successfully obtained the crystal of dianion intermediate,which was determined by X-ray diffraction.Subsequently,dilithio reagents successfully were applied in organic synthesis.When deuterium oxide was used as electrophile to react with the dilithio reagents,α,β-dideuterioketones were efficiently obtained.While trimethylsilane chloride was used as electrophile to react with the dilithio reagents, allyloxylsilanes and silyl enol ethers were obtained.These results demonstrated that the dilithio reagent can react with various electrophiles to form various carbon-carbon bonds and carbon-heteroatom bonds.更多还原