A Theoretical Investigation on the Mechanism and Stereochemical Course of the Addition of (E)-2-Butenyltrimethylsilane to Acetaldehyde by Electrophilic and Nucleophilic Activation

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• 作者：Larry M. Wolf ; Scott E. Denmark
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：March 27, 2013
• 年：2013
• 卷：135
• 期：12
• 页码：4743-4756
• 全文大小：781K
• 年卷期：v.135,no.12(March 27, 2013)
• ISSN：1520-5126

文摘

The diastereoselectivity of the addition of (E)-2-butenyltrimethylsilane to acetaldehyde under electrophilic (BF₃, H₃O⁺) and nucleophilic (F^{鈥?/sup>) activation is investigated using density functional theory (M06-2X). The interaction鈥揹istortion/activation鈥搒train model of reactivity is used to rationalize the origin of the selectivity. Consistent with experimental model systems, the synclinal transition states are determined to be preferred over the antiperiplanar transition states in the electrophilic-activated manifolds and vice versa for the fluoride-activated manifold. The selectivity for the syn diastereomer in the electrophilic activation manifolds is accounted for by increased electrostatic and orbital interactions for a synclinal transition state (syn-T3) at the expense of increased steric interactions relative to antiperiplanar transition states. The enhanced orbital interactions for the synclinal (syn-T3) versus antiperiplanar transition states can be attributed to increased 蟺鈫捪€* interactions. The selectivity for the anti diastereomer in the nucleophilic manifold is explained by the lesser electrostatic repulsion in the antiperiplanar transition states which are favored relative to the synclinal transition states. Additionally, the diastereoselectivity is partly attributed to variation in the distortion of the crotylsilane.}