I2/DMSO-Catalyzed Transformation of N-tosylhydrazones to 1,2,3-thiadiazoles

Abstract

An iodine/DMSO catalyzed selective cyclization of N-tosylhydrazones with sulfur without adding external oxidant was developed for the synthesis of 4-aryl-1,2,3-thiadiazoles. In this reaction, oxidation of HI by using DMSO as dual oxidant and solvent is the key, which allowed the regeneration of I 2 , ensuring thus the success of the synthesis. This protocol features by simple operation, high step-economy (one-pot fashion), broad substrate scope as well as scale-up ability.

Investigation on the Synthesis, Application and Structural Features of Heteroaryl 1,2-Diketones

“… 30 , 31 Practically, iodine I 2 is often used in combination with other oxidants and I 2 functions as a promoter. 32 , 33 Thus, various chemicals were tested in combination with I 2 in our study to further promote the oxidation step shown in Scheme 2 . The addition of I 2 , DMSO and CuO directly into the heteroarylation reaction mixture produced the desired products, though the yields were very low ( Table 1 , Entry 1).…”

“…Aerobic oxidations have been reported to convert vinyl or alkyl groups, especially benzylic alkyl groups to alcohols, aldehydes, ketones, carboxylic acids, etc. , The oxidation of ketones to diketones using catalytic 1,4-diazabicyclo[2.2.2]­octane (DABCO) in the presence of air in a recent report showed similarities with our reaction system . The formation of diketone could also be facilitated by oxidizing agents such as I 2 . , Some mild oxidizing agents have been reported to successfully facilitate selective oxidation for palladium-catalyzed reactions. , Practically, iodine I 2 is often used in combination with other oxidants and I 2 functions as a promoter. , Thus, various chemicals were tested in combination with I 2 in our study to further promote the oxidation step shown in Scheme . The addition of I 2 , DMSO and CuO directly into the heteroarylation reaction mixture produced the desired products, though the yields were very low (Table , Entry 1). , In order to obtain better yields, the heteroarylation product was briefly worked up with a simple extraction and then the crude product was carried forward to the oxidation step.…”

Update on the Synthesis of N‐Heterocycles via Cyclization of Hydrazones (2017–2021)

“…The use of DMSO as a dual oxidant and solvent is a key point (Scheme 59a). [110] In addition, this strategy has the distinct advantage of avoiding the use of external oxidants. Later, the Peddinti's group developed an iodine-catalyzed denitrative imino-diaza-Nazarov cyclization method of constructing pyrazoles using α-nitroacetophenone derivatives 380 and hydrazones as starting materials (Scheme 59b).…”

I2/DMSO-catalyzed one-pot approach for the synthesis of 1,3,4-selenadiazoles

“…In recent times, the iodine/DMSO combination has received considerable attention, in synthetic organic chemistry, as an effective and eco-friendly oxidative system as it has affected numerous organic transformations. [18][19][20][21][22] As our continuous work on the development of a new method for the synthesis of various heterocyclic biologically active molecules, we herein report iodine/DMSO catalysed a three-component reaction for the preparation of 1,3,4-selenathiazoles from the easily available, aryl aldehyde, hydrazine and selenium powder.…”