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Theoretical Studies on the Origins of the Regio‐ and Stereoselectivities of Nickel Catalyzed Intermolecular [2+2] Cycloaddition of Conjungated Enynes with Alkenes
Author(s) -
Guo Chenchen,
Jiao Mingyang,
Wang Huiqun,
Li Yajie,
Chen BoZhen
Publication year - 2016
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201600701
Subject(s) - cycloaddition , alkene , cyclobutene , chemistry , regioselectivity , enyne , substituent , isomerization , conjugated system , nickel , stereoselectivity , catalysis , reductive elimination , medicinal chemistry , stereochemistry , organic chemistry , ring (chemistry) , polymer
We have investigated the nickel catalyzed [2+2] cycloaddition of conjugated enynes with the cyclic and acyclic alkenes using DFT B3LYP and M06‐L methods. The calculation results show that the cycloaddition includes the formation of the C ‐enolate intermediate and the reductive elimination to form the cyclobutene. The electron‐withdrawing substituent should be the key structure leading to the regioselectivity in the reaction of the conjugated enyne with the cyclic alkene. The stereoselectivity of the cycloaddition between Z/E ‐alkenes and enynes is attributed to the isomerization from Z ‐alkenes to E ‐alkenes after they coordinate to the nickel. Besides, the conjugated structure in enynes plays an essential role in the [2+2] cycloaddition and in the absence of it the reductive coupling will be more favorable than the cycloaddition.