Hyperconjugation Involving Strained Carbon–Carbon Bonds. Structural Analysis of Ester and Ether Derivatives and One-Bond <sup>13</sup>C–<sup>13</sup>C Coupling Constants of α- and β-Nopinol
作者:Shinn Dee Yeoh、Colin E. Skene、Jonathan M. White
DOI:10.1021/jo3020243
日期:2013.1.18
σC–C–σ*C–O interactions involving the strained carbon–carbon bonds of α- and β-nopinol, and their ester and ether derivatives have been demonstrated in the solid state using the variable oxygen probe. These hyperconjugative interactions are manifested as a strong response of the C–OR bond distance to the electron demand of the OR substituent. Although the effects upon the donor C–C bond distances are
σ C-C -σ* C-O涉及α-和β-nopinol,和它们的酯和醚衍生物的应变碳-碳键的相互作用已在固态使用可变氧探头被证明。这些超共轭相互作用表现为C-OR键距离对OR取代基的电子需求的强烈响应。尽管对供体CC键距离的影响不够大,无法通过X射线晶体学测量,但它们的确对13 C- 13产生了系统且可测量的影响C单键耦合常数。对于施主CC键,随着OR的电子需求增加,耦合常数降低,与该键的弱化相一致,而中间CC键耦合常数则与键增强相符,其增加。