Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095 , United States.
Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM) , Vrije Universiteit Amsterdam , 1081 HV Amsterdam , The Netherlands.
J Org Chem. 2018 Mar 16;83(6):3164-3170. doi: 10.1021/acs.joc.8b00025. Epub 2018 Mar 7.
The endo and exo stereoselectivities of Diels-Alder reactions of cyclopropenone, iminocyclopropene, and substituted triafulvenes with butadiene were rationalized using density functional theory calculations. When cyclopropenone is the dienophile, there is a 1.8 kcal/mol preference for the exo cycloaddition with butadiene, while the reaction of 3-difluoromethylene triafulvene with butadiene favors the endo cycloaddition by 2.8 kcal/mol. The influence of charge transfer and secondary orbital interactions on the stereoselectivity of Diels-Alder reactions involving triafulvenes and heteroanalogs is discussed. The predicted stereoselectivity correlates with both the charge and highest occupied molecular orbital (HOMO) coefficient at the C carbon of the triafulvene motif.
用密度泛函理论计算对环丙烯酮、亚胺环丙烯和取代的三并呋喃与丁二烯的 Diels-Alder 反应的内型和外型立体选择性进行了合理化。当环丙烯酮为亲二烯体时，与丁二烯的外向环加成具有 1.8 kcal/mol 的优势，而 3-二氟亚甲基三并呋喃与丁二烯的反应则有利于内向环加成，优势为 2.8 kcal/mol。讨论了电荷转移和次级轨道相互作用对涉及三并呋喃和杂原子类似物的 Diels-Alder 反应立体选择性的影响。预测的立体选择性与三并呋喃基元的 C 碳上的电荷和最高占据分子轨道（HOMO）系数相关。
