Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
Organisch Chemisches Institut, Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany.
Angew Chem Int Ed Engl. 2016 Feb 5;55(6):2022-7. doi: 10.1002/anie.201508980. Epub 2016 Jan 6.
The origin of stereoselectivity in the (3+2) annulation of allenes and enones catalyzed by an amino acid derived phosphine catalyst has been investigated by the use of dispersion-corrected density functional theory. An intermolecular hydrogen bond between the intermediate zwitterion and the enone was found to be the key interaction in the two enantiomeric transition states. Additional stabilization is provided by intermolecular hydrogen-bonding interactions between acidic positions on the catalyst backbone and the substrate. Enantioselectivity occurs because the intermolecular hydrogen bond in the transition state leading to the minor enantiomer is only possible at the expense of reactant distortion.
通过使用色散校正密度泛函理论，研究了由氨基酸衍生的膦催化剂催化的丙二烯和烯酮的（3+2）环加成反应中立体选择性的起源。发现中间体两性离子与烯酮之间的分子间氢键是两种对映异构过渡态的关键相互作用。催化剂主链上的酸性位置与底物之间的分子间氢键相互作用提供了额外的稳定性。对映选择性的产生是因为导致非对映异构体的过渡态中的分子间氢键只能以反应物变形为代价才能形成。
