Recent Developments in the Synthesis of 1,2,5-Thiadiazoles and 2,1,3-Benzothiadiazoles

Abstract

The fast-growing interest in 1,2,5-thiadiazoles and their fused analogues including 2,1,3-benzothiadiazoles in recent years as important compounds in materials science and biomedicine has led to great progress in the synthesis of these heterocyclic systems. In this short review, the development of known procedures together with novel reactions is covered. New starting materials, unknown and unexpected transformations for the construction of the thiadiazole ring are emphasized.1 Introduction2 Synthesis of Monocyclic 1,2,5-Thiadiazoles2.1 From 1,2-Diamines, vic-Dioximes and Related Compounds2.2 From Alkyl Aryl (Hetaryl) Ketoximes and Tetrasulfur Tetranitride2.3 By Condensation Reactions2.4 From Other Heterocycles3 Synthesis of Fused 1,2,5-Thiadiazoles3.1 From ortho-Phenylenediamines and Related Compounds3.2 From ortho-Aminonitroso and ortho-Aminonitro Derivatives3.3 By Condensation Reactions3.4 By Chalcogen Exchange in 1,2,5-Oxa- and 1,2,5-Selenadiazoles3.5 Miscellaneous Methods4 Conclusions

Benzothiadiazole vs. iso-Benzothiadiazole: Synthesis, Electrochemical and Optical Properties of D–A–D Conjugated Molecules Based on Them

“…Despite the fact that 4,7-dibromobenzo[ c ][1,2,5]thiadiazole has been extensively studied for the past 20 years [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ], its closest isomer, 4,7-dibromobenzo[ d ][1,2,3]thiadiazole 1 , was first synthesized relatively recently in 2016 [ 9 ]. The obtaining of dibromide 1 , as previously described [ 9 ], involves the bromination reaction of benzo[ d ][1,2,3]thiadiazole 2 , which was obtained using the commercially available 2-aminobenzenethiol with a nitrosation reaction followed by intramolecular cyclization ( Scheme 1 ) [ 19 ].…”

“…Benzo[ c ][1,2,5]thiadiazole (BTD) appears to be one of the most widely used acceptor heterocycles in producing donor-acceptor materials for organic electronics [ 1 , 2 , 3 , 4 ]. The symmetric structures, in which the 4 and 7 positions of the benzothiadiazole ring are replaced by identical substituents, are widely used as monomers for the obtaining of donor-acceptor polymers, and for the synthesis of small molecules with various useful photovoltaic properties [ 5 , 6 , 7 , 8 ]. The strong electron-acceptor properties of BTD provide materials based on it with the necessary properties (band gap, charge transport properties, intra- and intermolecular interactions, etc.…”

New 3,1,2,4-benzothiaselenadiazines, related π-heterocycles including Herz cations, radicals and molecular complexes, and Bunte salts

“…Chalcogen–nitrogen π-heterocyclic chemistry is very diverse and rich in aspects of structure and reactivity. 1,25 This work adds original new findings to the field. In particular, it is shown that the electrophilic cyclization of Ar–NSN–SiMe 3 under the action of chalcogen chlorides can be used not only for the synthesis of 1,3,2,4-benzodithiadiazines and 1,2,4,3,5-benzotrithiadiazepines but also of 3,1,2,4-benzothiaselenadiazines.…”

8,8′-(Benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(quinolin-4(1H)-one): a twisted photosensitizer with AIE properties

“…Product 5 precipitated from the reaction mixture and, following a simple ltration and subsequent washes with THF and EtOH, was collected as a yellow semi-crystalline powder without the need for further purication, as determined by LC-MS (ESI, S2.5 and S2.6 †). Compound 5 exhibited very poor solubility in both polar and non-polar solvents (ESI, S2.7 †); hot DMSO only sparingly dissolved the compound and was not suitable for obtaining satisfactory 13 C NMR data. Fortunately, compound 5 dissolved in triuoroacetic acid (TFA), forming the salt 5H 2 2+ 2TFA À (referred to as 5H 2 2+ ).…”

“…BTZ and its derivatives have an appealing set of properties which can make them useful building blocks for developing new photoactive materials. [11][12][13] These include their biocompatibility, and their strong electron-withdrawing character that makes them useful partners in donor (D)-acceptor (A) or D-A-D photoactive systems as well as in organic semiconductor materials such as photovoltaics and OLEDs. 14 As part of our work on new molecular and polymeric BTZ containing photoactive materials, [15][16][17][18] we have developed a high yielding, scalable and rapid synthesis of a new quinolin-4-ol incorporating a central BTZ unit.…”