Format

Send to

Choose Destination
Chem Asian J. 2016 Oct 20;11(20):2867-2875. doi: 10.1002/asia.201600709. Epub 2016 Aug 5.

Palladium-Catalyzed Desymmetrization of Silacyclobutanes with Alkynes to Silicon-Stereogenic Silanes: A Density Functional Theory Study.

Author information

1
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, No. 1378, Wenyi West Road, Science Park of HZNU, Hangzhou, 311121, China.
2
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, No. 1378, Wenyi West Road, Science Park of HZNU, Hangzhou, 311121, China. zhengxu@hznu.edu.cn.
3
Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, No. 1378, Wenyi West Road, Science Park of HZNU, Hangzhou, 311121, China. liwenxu@hznu.edu.cn.
4
State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, P.R. China. liwenxu@hznu.edu.cn.

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 Pd0 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 PdII intermediate was found to be the rate-determining step, whereas the enantioselectivity-determining step, oxidative addition of silacyclobutane to the three-membered metallocyclic PdII intermediate, was found to be quite sensitive to the steric repulsion between the chiral ligand and silacyclobutane.

KEYWORDS:

density functional calculations; desymmetrization; reaction mechanisms; ring expansion; silylation

PMID:
27325305
DOI:
10.1002/asia.201600709

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center