Chronology of CH center dot center dot center dot O Hydrogen Bonding from Molecular Dynamics Studies of the Phosphoric Acid-Catalyzed Allylboration of Benzaldehyde

作者：Grayson Matthew N; Yang Zhongyue; Houk K N^*

来源：Journal of the American Chemical Society, 2017, 139(23): 7717-7720.

DOI：10.1021/jacs.7b03847

CH center dot center dot center dot O hydrogen bonds involving formyl groups have been invoked as a crucial factor controlling many asymmetric transformations. We conducted quasi classical direct molecular dynamics simulations on the phosphoric acid-catalyzed allylboration of benzaldehyde to understand the synergy between the phosphoric acid OH center dot center dot center dot O hydrogen bond and the secondary CH center dot center dot center dot O formyl hydrogen bond as the reaction occurs. In the gas phase, both the CH center dot center dot center dot O and OH center dot center dot center dot O hydrogen bonds are enhanced from reactants to transition states. In toluene, the trend of H-bond enhancement is observed with a smaller magnitude because of solvent caging. The strength of the formyl hydrogen bond in the TS, a second CH center dot center dot center dot O interaction between the P=O oxygen and ortho-hydrogen of the phenyl ring and the OH center dot center dot center dot O hydrogen bond were determined using quantum mechanical calculations (4.6, 1.0, and 14.5 kcal mol(-1), respectively).

• 出版日期2017-6-14