Synthesis of Silafluorenes by Iridium-Catalyzed [2 + 2 + 2] Cycloaddition of Silicon-Bridged Diynes with Alkynes

Abstract

[reaction: see text] Silicon-bridged 1,6-diynes underwent [2 + 2 + 2] cycloaddition with alkynes in the presence of an iridium(I)-phosphine catalyst to afford densely substituted silafluorene derivatives. Extended silafluorene skeletons were constructed by the [2 + 2 + 2] cycloaddition of tetraynes.

Synthesis of Novel Ladder Bis-Silicon-Bridged p-Terphenyls

“…6 However, little attention has been paid to the siliconbridged ladder oligo-or poly(p-phenylene)s. Until very recently, the first example of a bis-silicon-bridged p-terphenyl had been synthesized by Murakami and co-workers on the basis of the elegant iridium(I)-catalyzed double [2 + 2 + 2] cycloaddition. 7 (1) For recent reviews, see: In this paper, we disclose a new entry into this class of molecules formed by a sequential tetralithiation and double silacyclization reactions. Crystal structures and fundamental photophysical properties of the new molecules will also be reported.…”

Poly(dibenzosilole)s

“…Cao and coworkers obtained the 3,6-dibenzosilole monomers through diamine intermediates using the diazotiScheme 3 Synthesis of poly(3,6-dibenzosilole) reported by Holmes and coworkers [41]. Reagents and conditions: (a) n-BuLi, THF, -78 to In a recent communication, an asymmetric dibenzosilole moiety was reported [43]. Using an iridium-catalysed [2 + 2 + 2] cycloaddition of siliconbridged diynes and alkynes, various asymmetric dibenzosilole units were obtained in yields of up to 93% (Scheme 5).…”

“…These novel dibenzosilole compounds can potentially lead to AB monomers for polymerisation. LadderScheme 5 Synthesis of dibenzosilole using iridium-catalyzed [2 + 2 + 2] cycloaddition [43]. Reagents and conditions: (a) [IrCl(COD)] 2 2.5 mol %, PPh 3 10 mol %, Bu 2 O, 110 • C, 24 h type dibenzosilole compounds, such as 50, were also synthesised using the same method opening an opportunity for the synthesis of dibenzosilolebased rigid planar polymers (Scheme 5).…”

Silicon-Bridged Biaryls: Molecular Design, New Synthesis, and Luminescence Control

“…1). 27 We, therefore, began to study for invention of new syntheses of silicon-bridged biaryls, including 9-silafluorenes. …”