A challenging synthesis of new 1,3,4‐thiadiazole derivatives starting from 2‐acylamino‐3,3‐dichloroacrylonitriles

Abstract

Available 2‐acylamino‐3,3‐dichloroacrylonitriles, when treated with hydrazine hydrate, provide 2‐alkyl‐ or 2‐aryl‐5‐hydrazino‐1,3‐oxazole‐4‐carbonitriles that readily add alkyl or aryl isothiocyanates and the adducts formed recyclize on heating. Finally, the synthesis results in 5‐alkyl(aryl)amino‐1,3,4‐thiadiazol‐2‐yl(acylamino)acetonitriles or the products of their further cyclization, 2‐(5‐amino‐1,3‐ oxazol‐2‐yl)‐1,3,4‐thiadiazole derivatives. The structures of the novel substituted 1,3,4‐thiadiazoles are corroborated spectroscopically as well as by X‐ray diffraction method. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:454–458, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20041

Preparative conversion of chloralamides to 2,5‐diaryl‐3a,6a‐dihydro‐[1,3]thiazolo[4,5‐d][1,3]thiazoles with the Lawesson reagent

“…To conclude, the successive conversions 1 →→ 4 →→ 7 yield a novel bicyclic system, 3a,6a-dihydro [1,3]thiazolo [4,5-d] [1,3]thiazole, and the applicational aspect of this finding calls for further study. The synthetic approach proposed here is of particular significance in view of the fact that nonaromatic compounds 7a,c,g are readily oxidized with manganese dioxide to furnish the corresponding bicyclic heteroaromatics 10a,c,g, containing two [d]-annelated thiazole rings (Scheme 1).…”

“…The product was purified by recrystallization from dioxane; yield: General Procedure for the Synthesis of 2,5-Diaryl-3a,6a-dihydro [1,3]thiazolo [4,5-d] [1,3]thiazoles (7a-e) and 2-Aryl-5-thien-2-yl-3a,6a-dihydro [1,3]thiazolo [4,5-d] [1,3]…”

“…Chloral adducts of carboxamides, so-called chloralamides, have already found wide application in the azole and azine synthesis, as reported, for example, in the relevant monograph [1] and the most recent publications [2][3][4][5]. Here we propose an original method to convert readily available chloralamides 1a-c to 2,5-disubstituted derivatives of 3a,6a-dihydro [1,3]thiazolo [4,5-d] [1,3]thiazole, a novel heterocyclic system (Scheme 1).…”

“…Here we propose an original method to convert readily available chloralamides 1a-c to 2,5-disubstituted derivatives of 3a,6a-dihydro [1,3]thiazolo [4,5-d] [1,3]thiazole, a novel heterocyclic system (Scheme 1).…”

A facile synthesis of new 1,2‐dihydro‐2λ5‐[1,3]oxazolo[5,4‐d][1,3,2]diazaphosphinine derivatives starting from 2‐benzoylamino‐3, 3‐dichloroacrylonitrile

“…Starting from 2-acylamino-3,3-dichloroacrylonitriles used as polycentric electrophiles, synthetic routes were previously developed to access various derivatives of 1,3-oxazole [1][2][3][4][5][6][7][8], 1,3-thiazole [7], imidazole [9], pyrazole [10,11], 1,3,4-oxadiazole [12], 1,3,4-thiadiazole [13], pyrazolo [1,5-…”