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Zinc-mediated Chain Extension Reaction of 1,3-diketones to 1,4-diketones

Author: LiuHuiFang
Tutor: XueSong
School: Tianjin University of Technology
Course: Applied Chemistry
Keywords: organozinc reagents β-diketones chain extension
CLC: O643.32
Type: Master's thesis
Year: 2011
Downloads: 58
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Abstract


Recently, the chemical world pay more and more attention adout organozinc reagents. Organozinc reagents are kind of the earliest prepared organometallics in organic synthesis. Compared with the organic magnesium and organolithium, organozinc reagents have advantages, such as excellent functionality compatibility, high chemoselectivity, regioselectivity and stereoselectivity etc, in organic synthetic chemistry owing to their low reactivity. Additionally, they also can change with a variety of transition metal salts and lead to new transition metal compounds, and the resulting organometallics can react with many organic electrophiles. Organozinc reagents are so good, which could open up an new area. 1,4-Diketones are important and valuable intermediates for the synthesis of cyclopentenones, five-membered heterocycles, and crown esters.This dissertation is mainly focused on the application of organozinc reagents in the chain extension reaction ofβ-diketones which could be prepared one step by cheap raw materials. This dissertation includes three chapters.Chapter one: The methods of Preparation of organozinc reagents and application in organic synthesis. In this section, a brief introduction of the history of organozinc reagents was given, and then detailed the application of functional organozinc reagents in organic synthesis.Chapter two: Researched the application of organozinc reagents in the chain extension reaction ofβ-diketones. In this chapter, we first investigate the conditions of the reaction, gaining the optimum process conditions, the optimum ratio ofβ-diketones:ZnEt2:CF3COOH:CH2I2 is 1:2.5:1.25:2.5 and the optimum time is 24 h. Secondly, a variety of substrates were extended in this optimum process condition to examine the impact of electronic effects and steric hindrance on the reaction. Electronic effects were investigated fistly. Clearly, the substrate with an electron-donating group on the aromatic ring gave better yield than that of an electron-withdrawing group on the aromatic ring. For example, the substrates contained a methoxyl group on the aromatic ring gave the corresponding product in 73%. It was found that no desired product was observed when 2-methyl-1-phenylbutane-1,3-dione was used as substrate under the typical reaction conditions, which might be due to steric hindrance of the methyl group.Chapter four: The work of the research was summarized.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalytic reaction
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