1,2,5-Thiadiazoles

Efficient Synthesis of 4,8-Dibromo Derivative of Strong Electron-Deficient Benzo[1,2-d:4,5-d’]bis([1,2,3]thiadiazole) and Its SNAr and Cross-Coupling Reactions

“…The choice of acceptor is crucial to achieving high performance in materials such as bulk heterojunction solar cells (BHJ) [ 4 , 5 ], dye-sensitized solar cells (DSSCs) [ 4 , 6 , 7 ], n-type organic field-effect transistors [ 8 , 9 ], near-infrared absorption and emissions materials [ 10 , 11 ], and electrochromic materials [ 12 , 13 ]. Although many heterocyclic acceptor building blocks are known [ 14 ], 2,1,3-benzothiadiazole (BTD) occupies an exceptional place among them [ 15 , 16 ]. Nevertheless, there is a strong demand to create ultra-high electron-deficient building blocks based on it to improve the special characteristics of photovoltaic materials [ 17 , 18 ].…”

Tuning Molecular Electron Affinities against Atomic Electronegativities by Spatial Expansion of a π‐System

“…It should be noted that compounds E/H, E/R and E/R', which are 10π-electron hetarenes, are widely used in contemporary chemistry and materials science due to a unique set of properties including high EAA, dualistic Lewis ambiphilicity; enhanced chromophoric/fluorophoric performances; redox ac-tivity; and a propensity to secondary bonding interactions with special emphasis on chalcogen bonding. [12][13][14][15][16][17][18][19][20] In some fundamental and applied aspects their EAA, highlighted by the formation of CT complexes and radical anions (RAs), plays the key role. [13,[18][19][20][21][22][23][24][25][26] The new effect described in this work clarifies some earlier unexplained findings, e. g. regarded to the EAA of C 6 R 6 benzene derivatives (R are the same as above).…”

The Photochemical Mediated Ring Contraction of 4H-1,2,6-Thiadiazines To Afford 1,2,5-Thiadiazol-3(2H)-one 1-Oxides

“…The chemistry and applications of 1,2,5-thiadiazoles have been extensively reviewed. 2,3,5,6 1,2,5-Thiadiazol-3(2H)-one 1-oxides are a rare subclass with ∼15 structures reported in the literature. 6 Interestingly, in 1982, a Merck patent described 1,2,5thiadiazol-3(2H)-one 1-oxides, cf., compound 1, as elastase inhibitors for the treatment of diseases like pancreatitis, emphysema, and rheumatoid arthritis (Figure 1).…”

“…Recently, we reported the unexpected ring contraction of spiro(benzo[d] [1,3]dioxole-2,4′- [1,2,6]thiadiazines) 2 to thiadiazoles 3 in high yields, under thermal and Brønsted or Lewis acid-catalyzed conditions (Scheme 1), 9,10 In the current work, while investigating 3,5-diphenyl-4H-1,2,6-thiadiazin-4-one (4a) as a potential photosensitizer for singlet oxygen ( 1 O 2 ) production, rapid photobleaching of the chromophore led to a new colorless product 5a. The loss of color indicated reduced conjugation [5a: λ max (DCM) 296 nm (log ε = 4.26) vs 4a: λ max (DCM) 431 nm (log ε = 3.44) 11 ], while 13 The remarkable ring contraction presented herein leads to oxidation of an imine motif to an imide and the selective mono-oxidation of the ring sulfur to a stereogenic sulfoxide with only the substrate, solvent, visible light, and air present under ambient conditions.…”

“…1,2,5-Thiadiazole is a privileged motif in medicinal chemistry, − and appears in the beta blocker Timolol that was patented as early as 1968 (Figure ). The chemistry and applications of 1,2,5-thiadiazoles have been extensively reviewed. ,,, 1,2,5‑Thiadiazol-3­(2 H )-one 1-oxides are a rare subclass with ∼15 structures reported in the literature . Interestingly, in 1982, a Merck patent described 1,2,5-thiadiazol-3­(2 H )-one 1-oxides, cf.…”