Synthesis of Benzothiadiazole Derivatives by Applying C–C Cross-Couplings

Abstract

The benzothiadiazole moiety has been extensively exploited as a building block in the syntheses of efficient organic semiconducting materials during the past decade. In this paper, parallel synthetic routes to benzothiadiazole derivatives, inspired by previous computational findings, are reported. The results presented here show that various C-C cross-couplings of benzothiadiazole, thiophene, and thiazole derivatives can be efficiently performed by applying Xantphos as a ligand of the catalyst system. Moreover, improved and convenient methods to synthesize important chemical building blocks, e.g., 4,7-dibromo-2,1,3-benzothiadiazole, in good to quantitative yields are presented. Additionally, the feasibility of Suzuki-Miyaura and direct coupling methods are compared in the synthesis of target benzothiadiazole derivatives. The computational characterization of the prepared benzothiadiazole derivatives shows that these compounds have planar molecular backbones and the possibility of intramolecular charge transfer upon excitation. The experimental electrochemical and spectroscopic studies reveal that although the compounds have similar electronic and optical properties in solution, they behave differently in solid state due to the different alkyl side-group substitutions in the molecular backbone. These benzothiadiazole derivatives can be potentially used as building blocks in the construction of more advanced small molecule organic semiconductors with acceptor-donor-acceptor motifs.

Carbazole-based small molecule electron donors: Syntheses, characterization, and material properties

“…Recently, we reported a synthetic pathway to BT-based building blocks [27]. Since then, we have further developed the synthetic strategy and, here, we present the syntheses of two unsymmetrical D-A and two symmetrical A-D-A type small molecules.…”

“…Furthermore, the attachment of fluoro substituents in the A units has a positive effect on all solar cell device parameters. Moreover, the computational studies revealed that the molecular structures are twisted between the central carbazole D unit and -bridge which may result in inefficient intramolecular charge transfer and, also, relatively limited short-circuit currents in OSC devices.Recently, we reported a synthetic pathway to BT-based building blocks [27]. Since then, we have further developed the synthetic strategy and, here, we present the syntheses of two unsymmetrical D-A and two symmetrical A-D-A type small molecules.…”

“…">Experimental sectionCommercial reagents were used as received. 2-(3-Hexylthiophen-2-yl)-5-(4,4,5,5tetramethyl-1,3,2-dioxaborolan-2-yl)thiazole and compound 3b were synthesized using the previously published methods [27]. The chemical structures of new compounds were characterized by using NMR and HRMS techniques.…”

A Nickel‐Salphen Type Complex with a Heteropicene Backbone

“…The synthesis starts with the twofold Suzuki‐Miyaura cross‐coupling of dibromo benzothiadiazole 1 and thienylboronic ester 2 , giving benzothiadiazole 3 in 77 % yield (Scheme ). Treatment with LiAlH 4 transforms 3 into the diamine 4 nearly quantitatively.…”

“…General Remarks: Commercially available reagents were obtained from Chempur, Fisher Scientific, abcr, Alfa Aesar, Sigma‐Aldrich or VWR and have been used without further purification unless otherwise mentioned. Compound 1 was synthesized similar to known procedure . The synthesis of compound 2 can be found in the Supporting Information.…”