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Page 22
Journal of Organic & Inorganic Chemistry
ISSN 2472-1123
2 n d E d i t i o n o f E u r o S c i C o n C o n f e r e n c e o n
Chemistry
F e b r u a r y 1 9 - 2 0 , 2 0 1 9
P r a g u e , C z e c h R e p u b l i c
Chemistry 2019
Asilyl cation is well known to be one of the highly reactive Lewis acids, and
is available for activation of unsaturated compounds. We developed a sila-
Friedel–Crafts reaction, in which the addition of silyl cation to the aromatic
moiety followed by deprotonation induces Si-C bond formation and applied it
to synthesize various dibenzosiloles such as trisilasumanene and so on. We
thoughtanintermediarysilylcationoritsarenecomplexcanaddtomultiplebonds
to form -silyl cations, which undergo Friedel-Crafts reaction with an aromatic
ring existed in a molecule to give the corresponding silacyclic compounds.
We have investigated the reactions using dialkylbenzylhydrosilanes and
dialkylhydro-1-naphthylsilanes as precursors of silyl cations, alkynes, alkenes,
allenes, carbon dioxide, and aldehydes as multiply bonded compounds, trityl
tetrakis(pentafluorophenyl)borate (TPFPB) as a hydride-abstracting reagent,
and 2,6-di-tert-butyl-4-methylpyridine as a base. Interestingly, we have found
that cyclization occurred only at the 8-position of the naphthalene ring in the
reactions using dialkyl-1-naphthylsilanes and alkenes. We also studied on
intramolecular version of the reactions using alkynes. Namely, we prepared
aromaticcompoundsbearing trimethylsilyl- ethynyl anddialkylhydrosilyl groups
at the neighboring position and treated them with a small amount of TPFPB
to give the corresponding aromatic ring-fused siloles and disiloles via single
and double intramolecular chain hydrosilylation reactions with silyl cations as
chain carriers, respectively. In these reactions, -silyl cations are considered to
have undergone hydride abstraction from the starting hydrosilanes instead of
Friedel-Crafts reactions in the former reactions. In this presentation, we wish
to report on the details of these reactions.
Biography
Takayuki Kawashima has received his DSci degree in 1974
from the University of Tokyo under the supervision of Professor
Naoki Inamoto. He became a Professor of Department of
Chemistry, Graduate School of Science, The University of Tokyo
in 1998 via a Research Associate, a Lecturer, and an Associate
Professor. From 1976 to 1978, he did Postdoctoral research
with Professor J G Verkade at Iowa State University and with
Professor WG Bentrude at University of Utah. In 2010, he retired
and became Professor Emeritus at the University of Tokyo.
He is now a Visiting Professor of Graduate School of Science
and Technology, Gunma University after that of Gakushuin
University. He received 2013 The Society of Silicon Chemistry,
Japan Award. He has 263 original papers. He is a Member
of Editorial Board of Heteroatom Chemistry from 2003 and
International Board on International Conference on Phosphorus
Chemistry from 2006.
Synthesis of silacyclic compounds induced by addition of in-situ
generated silyl cations to multiple bonds
Takayuki Kawashima and H Arii
1Gunma University, Japan
2University of Miyazaki, Japan
Takayuki Kawashima et al., J Org Inorg Chem 2019, Volume: 5
DOI: 10.21767/2472-1123-C1-020