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Palladium‐Catalyzed Desymmetrization of Silacyclobutanes with Alkynes to Silicon‐Stereogenic Silanes: A Density Functional Theory Study
Author(s) -
Zhang Jin,
Xu JinZhou,
Zheng ZhanJiang,
Xu Zheng,
Cui YuMing,
Cao Jian,
Xu LiWen
Publication year - 2016
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201600709
Subject(s) - catalytic cycle , stereocenter , palladium , desymmetrization , silanes , chemistry , oxidative addition , alkyne , ligand (biochemistry) , catalysis , density functional theory , stereochemistry , computational chemistry , organic chemistry , enantioselective synthesis , silane , biochemistry , receptor
Abstract The palladium‐catalyzed desymmetrization of silacyclobutanes using electron‐deficient alkynes proceeds with high enantioselectivity in the presence of a chiral P ligand; this provides a facile approach for the synthesis of novel silicon‐stereogenic silanes. In this work, we used hybrid density functional theory (DFT) to elucidate the mechanism of the palladium‐catalyzed desymmetrization of silacyclobutanes with dimethyl acetylenedicarboxylate. Full catalytic cycle including two different initiation modes that were proposed to be a possible initial step to the formation of the 1‐pallada‐2‐silacyclopentane/alkyne intermediate—the oxidative addition of the palladium complex to the silacyclobutane Si−C bond (cycle MA) or coordination of the Pd 0 complex with the alkyne C≡C bond (cycle MB)—have been studied. It was found that the ring‐expansion reaction began with cycle MB is energetically more favorable. The formation of a seven‐membered metallocyclic Pd II intermediate was found to be the rate‐determining step, whereas the enantioselectivity‐determining step, oxidative addition of silacyclobutane to the three‐membered metallocyclic Pd II intermediate, was found to be quite sensitive to the steric repulsion between the chiral ligand and silacyclobutane.