Effective modulation of the photoluminescence properties of 2,1,3-benzothiadiazoles and 2,1,3-benzoselenadiazoles by Pd-catalyzed C–H bond arylations

Abstract

A one step procedure towards the synthesis of 4-aryl-2,1,3-benzothiadiazoles and 4-aryl-2,1,3-benzoselenadiazoles using Pd-catalyzed C–H bond arylations was developed.

Photophysical Characteristics of Polarity‐Sensitive and Lipid Droplet‐Specific Phenylbenzothiadiazoles

“…The compound was synthesized according to the general procedure using 4‐chlorophenylboronic acid (153 mg, 0.98 mmol, 2.1 equiv.). Purification by column chromatography (hexane/CH 2 Cl 2 1 : 1, R f =0.48) gave 7 as a colourless solid (55 mg, 48 %) whose characterization data was in accordance with reported literature [36] . 1 H NMR (400 MHz, CDCl 3 ): δ (ppm)=8.04−8.00 (m, 1H), 7.90−7.87 (m, 2H), 7.71−7.67 (m, 2H), 7.53−7.49 (m, 2H).…”

“…Purification by column chromatography (hexane/CH 2 Cl 2 85 : 15, R f = 0.30) gave 11 as a white solid (57 mg, 48 %) whose characterization data was in accordance with reported literature. [36] 1 H NMR (400 MHz, CDCl 3 ): δ (ppm) = 8.41À 8.38 (m, 2H), 8.16À 8.12 (m, 2H), 8.11 (dd, J = 8.5, 1.3 Hz, 1H), 7.79 (dd, J = 7.0, 1.3 Hz, 1H), 7.74 (dd, J = 8.5, 7.0 Hz, 1H). 13 C NMR (101 MHz, CDCl 3 ): δ (ppm) = 155.…”

Recent Developments in C–H Activation for Materials Science in the Center for Selective C–H Activation

“…The method proved efficient for a variety of electron-donating and electron-accepting aryl halide substrates and good-to-excellent yields are generally obtained. It should be noted that, under the conditions shown in Scheme 1 , C–H activation on the BT alone resulted in multiple arylation at the 5 and 6 positions in addition to the targeted 4 and 7 positions; however, Doucet and co-workers recently reported a phosphine-ligand free mono- and dual C–H activation of 2,1,3-benzothiadiazole in DMA solvent with high-to-moderate yields [ 22 ]. Unwanted over-arylation of the products was also seen when coupling the acceptors with 2-bromothiophenes having hydrogen in the 5-positions, which was addressed by the use of 2-bromo-5-(trimethylsilyl)thiophenes.…”

Electrophilicities of 4‐Nitrobenzochalcogenadiazoles

“…2,1,3-benzothia/selenadiazoles are neutral 10 π-electron heteroaromatics which have been actively investigated for the development of organic photovoltaics and organic lightemitting diodes. [1][2][3] Similar to many other chalcogen-nitrogen π-heterocycles, they possess high electron affinity making them effective electron acceptors. [4] For this reason, they represent a pivotal framework for the construction of organic dyes.…”

“…[15] In earlier work we have shown that 4-nitrobenzofurazan 1 c [16] is a representative of an another class of neutral electro-philes whose C-electrophilicity can be quantitatively described by the linear free enthalpy relationship (1), [17] where E parameter measures the strength of the electrophile, k is a second-order rate constant, while N and s N characterize the nucleophiles reactivity. log k ð20 � CÞ ¼ s N ðE þ NÞ (1) In an effort to obtain a quantitative measure of the reactivity of nitro derivatives of 2,1,3-benzothiadiazole and 2,1,3-benzoselenadiazole towards nucleophilic addition processes, [18][19][20][21][22][23][24] we now report on the kinetic and structural analysis of the coupling reaction of 4-nitrobenzothiadiazole 1 a and 4-nitrobenzoselenadiazole 1 b with the reference nitroalkyl anions 2 a-c (Scheme 1, Table 1) in order to evaluate the electrophilic parameter E at the C-7 position of the two electrophiles 1 a and 1 b according to Eq. (1) and to include them into the comprehensive electrophilicity scale of Mayr.…”