Bis-silicon-bridged stilbene homologues synthesized by new intramolecular reductive double cyclization.
A homologous series of bis-silicon-bridged stilbenes has been synthesized on the basis of a new intramolecular reductive cyclization of bis(o-silyl)-diphenylacetylene. Thus, the reaction of bis(o-silyl)-diphenylacetylenes with excess lithium naphthalenide undergoes the two-electron reduction at the acetylene moiety to produce a dianion intermediate, which further undergoes a double cyclization in a 5-exo mode to produce the bis-silicon-bridged stilbenes. This methodology can also be applied to the synthesis of tetrakis-silicon-bridged bis(styryl)benzenes. The silicon-bridged pi-conjugated systems thus prepared show intense fluorescence in the visible region. Comparison of a bis-silicon-bridged stilbene with its carbon analogue demonstrates the substantial effects of the silicon-bridges on the electronic structures and thus on the fluorescence properties.
Department of Chemistry, Graduate School of Science, Nagoya University, and PRESTO, Japan Science and Technology Corporation, Chikusa, Nagoya 464-8602, Japan. yamaguchi@chem.nagoya-u.ac.jp
Shigehiro
S
Yamaguchi
Caihong
C
Xu
Kohei
K
Tamao