Zirconium-Mediated Synthesis of Multi-substituted Dibenzosilole and Benzonaphthosilole Derivatives

In this study, a new zirconium-mediated cycloaddition for preparing dibenzosilole derivatives was developed using siliconbridged diynes and electron-withdrawing alkynes as starting materials. The preparation of silicon-bridged diynes from 1-bromide-2-iodobenzene, terminal alkynes, and dimethyldichlorosilane was also studied. Unlike in the previous synthesis methods, much higher yields of electron-withdrawing group-substituted dibenzosilole derivatives were obtained. In addition, a new synthesis strategy for preparing benzonaphthosilole derivatives using internal alkynes, 1,4-dibromobenzene, and electron-withdrawing alkynes as starting materials is proposed. Compared with previous methods, alkyl, phenyl, and electron-withdrawing groups can be successfully introduced onto aromatic rings, and the positions of these substituents can be easily controlled. The cycloaddition reactions for dibenzosilole and benzonaphthosilole derivatives are highly efficient one-pot processes, and the raw materials are available and easily prepared. Using these new methods, a series of novel multisubstituted dibenzonsilole and benzonaphthosilole derivatives were obtained effectively.

Synthesis Mediated by Zirconium, Crystal Structure and Theoretical Studies on Six-substituted Benzene with Silalactone Structure and Butadiene Derivative

A novel method for the synthesis of novel silalactone was proposed by iodation and zirconium-mediated cycloaddition of alkynes. 1,1-Dimethyl-4-carboxylatethyl-6,7-diphenyl-5-（trimethylsilyl）-1,3-dihydrobenzo[c][1,2]oxasilol-3（1 H）-one（compound 1） was obtained and characterized by X-ray single-crystal diffraction. It belongs to the monoclinic system, space group P2_1/n with a = 12.706（3）, b = 10.826（2）, c = 19.407（4） A, β = 91.50（3）°, V = 2668.4（9） A^3, Z = 4, F（000） = 1004, D_c = 1.182 mg/m^3, μ = 0.162 mm^-1, T = 293（2） K, S = 1.129, R = 0.0868 and wR = 0.1607 for 3542 observed reflections with I 〉 2σ（I）. The butadiene derivative, 3,6-di（2-methylphenyl）-4,5-diethylocta-3,5-diene（compound 2）, was synthesized by zirconacyclopentadiene and aryl iodides in the presence of Cu Cl and Pd（PPh3）4. It was characterized by X-ray single-crystal diffraction for the first time, belonging to the monoclinic system, space group C2/c with a = 19.015（4）, b = 7.7697（16）, c = 15.298（3） A, β = 98.24（3）°, V = 2236.8（8） A^3, Z = 8, F（000） = 760, D_c = 1.029 mg/m^3, μ = 0.057 mm^-1, T = 293（2） K, S = 1.100, R = 0.0673 and wR = 0.1391 for 1302 observed reflections with I 〉 2σ（I）.

Synthesis and Characterization of Three Pentacene Derivatives

The addition of substituents at the 6,13-position improved the solubility and stability of pentacene, making it possible to use the derivatives in spin coating of organic field-effect transistors(OFETs). Three pentacene derivatives, 6,13-bis(m-tolyl)pentacene(MP), 6,13-bis(4-butylphenyl)pentacene(BP), and 6,13-bis((4-butylphenyl)ethynyl)pentacene(BPEP) were synthesized, and their properties were investigated. 6,13-Pentacenequinone and organolithium were used in the preparation of 6,13-dihydropentacene at 0 ℃, and pentacene derivatives were synthesized with SnCl_2/HCl as reducing agent, to reduce 6,13-dihydropentacene at room temperature. The structure of the derivatives was characterized using NMR. The thermal stability, photochemical properties, and electronic structure of the three compounds were investigated using TGA, cyclic voltammetry, and UV–Vis. BPEP was also characterized using X-ray diffraction and atom force microscopy. BPEP was used to fabricate an OFET device using spin coating. The device showed a mobility of 0.07 cm^2 V s^(-1) at V_(th) =-10 V and I_(ON)/I _(OFF) = 10~2.