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Selenium‐Containing Heterocycles from Isoselenocyanates: Synthesis of 1H‐5‐Selena‐1,3,6‐triazaaceanthrylene Derivatives

“…Within our own research project, we have used aroyl isoselenocyanates 1a and Nphenylbenzimidoyl isoselenocyanates 1b as conveniently accessible, cheap and safe Se reagents for the preparation of 1,2,3-selenadiazole 2 [16] and 1,3-selenazole derivatives 3 [17], respectively (Scheme 1). In the case of 1c, treatment with amines led to 6H-5,1,3-benzoselenadiazocines 4 [18], whereas the base-catalyzed cyclization of 1d yielded bis(2,4-diarylimidazol-5-yl) diselenides 5 [5].…”

Selenium-Containing Heterocycles from Isoselenocyanates: Use of Hydrazine for the Synthesis of 1,3,4-Selenadiazine Derivatives

“…As a part of our program aimed at the development of simple new procedures for the synthesis of selenium-containing heterocycles [17][18][19][20][21][22][23][24], we have recently reported on the utility of isoselenocyanates as building blocks for the synthesis of 1,3-selenazetidines [25], 1,3-selenazolidines and perhydro-1,3-selenazines [26], 2-methylidene-1,3-selenazolidine derivatives [27], and 1,3-selenazepanes [28]. As an extension of this work, we report here on a novel and efficient synthesis of 1,3,4-selenadiazines.…”

New 1,2,3-Selenadiazole and 1,2,3-Thiadiazole Derivatives

“…Our synthetic procedure for new 1,2,3-selenadiazole and 1,2,3-thiadiazole derivatives started from a variety of ketones 1-5 containing α-methylene groups (Scheme 1) that were first converted into their corresponding tosyl or acyl hydrazones or semicarbazones and then further converted into 1,2,3-selenadiazole ring derivatives by the selenium dioxide oxidative ring closure of these semicarbazone or hydrazone derivatives [8][9][10][11] and into 1,2,3-thiadiazoles by reaction of the hydrazones or semicarbazones with thionyl chloride [12][13][14][15][16]. Scheme 1.…”