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Theoretical Study of the AlEt3-Promoted Tandem Reductive Rearrangement of Epoxides
Li-dong Zhang*, Hui-jun Guo, Yang Pan, Fei Qi*
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
Abstract:
The AlEt3-promoted tandem reductive rearrangement reactions of epoxides was studied at B3LYP/6-31G(d,p) level. For the model compound σ-hydroxy epoxides, two possible reaction pathways I and II were calculated. The main difference is the order of ethylene release and six- to five-member ring rearrangement.The ring contraction rearrangement in pathway I is the first step and this step is the rate controlling step with a free energy barrier of 116.62 kJ/mol. For pathway II, the ethylene release occurs first, and is followed by a six-member ring opening reaction which is the rate controlling step, and the barrier is 251.38 kJ/mol.The reason for such high barrier is that the ethylene release results in the following reaction being moredifficult. The results show that pathway I (C-C rearrangement and then ethylene release) is more favorable,which is consistent with experimental results.
Key words:  AlEt3, Rearrangement, Density functional theory, Diol, Epoxide
FundProject:
CH2和CH3分子在金属团簇Cun(n=1~6)上吸附性质
张李东*, 郭会军, 潘洋, 齐飞*
中国科学技术大学国家同步辐射实验室,合肥230029
摘要:
以σ-羟基环氧化合物作为模型化合物, 利用密度泛函中B3LYP/6-31G(d,p)的方法研究了三乙基铝促进的环氧化合物的重排还原有机串联反应机理. 根据乙烯消去和六元环重排顺序的不同可有两条可能的反应路径,路径I首先进行的是六元环的收缩重排,而且该步即决速步,能垒为116.62 kJ/mol;路径II中首先发生乙烯的消去然后进行六元环开环重排,开环反应步是该反应路径的决速步,相应的能垒为251.38 kJ/mol,如此高的能垒导致后续反应难于进行. 因此,路径I是更有利的反应路径,与实验结果一致.
关键词:  三乙基铝,重排,DFT,二醇,环氧化合物
DOI:10.1088/1674-0068/21/06/547-554
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