ChemInform Abstract: Synthesis and Tautomeric Structure of 2‐Arylazo‐4H‐imidazo[2,1‐b][1,3,4]thiadiazines.

Abstract

Synthesis and Tautomeric Structure of 2-Arylazo-4H-imidazo[2,1-b][1,3,4]thiadiazines. -20 Title compounds of type (III) are prepared. The study of their tautomeric structures by spectral analysis and by the Hammett correlation of their acid dissociation constants shows that they exist in the hydrazono form. -(SHAWALI*, A. S.; MOSSELHI, M. A. N.; FARGHALY, T. A.; J. Chem. Res. 2007, 8, 479-483; Dep. Chem., Fac. Sci., Cairo Univ., Giza 12613, Egypt; Eng.) -M. Bohle

Synthesis of bulky-tailed sulfonamides incorporating pyrido[2,3- d ][1,2,4]triazolo[4,3- a ]pyrimidin-1(5H)-yl) moieties and evaluation of their carbonic anhydrases I, II, IV and IX inhibitory effects

“…12 The hydrazonoyl chlorides 11a and 11b synthesis were started with the chlorination of the active methylene group of acetylacetone 7a and ethyl acetoacetate 7b using sulphuryl chloride to afford the α-chloroacetyl derivatives 8a and 8b, as described by Alihn in 1878. 15 Then by applying Japp-Klingemann coupling of the aforementioned α-chloroacetyl derivatives (8a and 8b) with the diazonium salts of sulfanilamide 10, we have got the acetyl derivative 11a and the ester derivative 11b in reasonable yields (65 and 72%, respectively) (Scheme 2 [16][17][18][19] This reaction proceeds via 1,3-dipolar cycloaddition of hydrazonoyl chlorides with dipolarophile thiones. 17 A literature review of this reaction almost exclusively prefers isomer 16 over 15 (Scheme 3).…”

“…15 Then by applying Japp-Klingemann coupling of the aforementioned α-chloroacetyl derivatives (8a and 8b) with the diazonium salts of sulfanilamide 10, we have got the acetyl derivative 11a and the ester derivative 11b in reasonable yields (65 and 72%, respectively) (Scheme 2 [16][17][18][19] This reaction proceeds via 1,3-dipolar cycloaddition of hydrazonoyl chlorides with dipolarophile thiones. 17 A literature review of this reaction almost exclusively prefers isomer 16 over 15 (Scheme 3). This suggest that the reaction process through the cyclo-addition of carbon 2 and nitrogen 3 of the pyrido[2,3-d]pyrimidine thiones with the hydrazonoyl chloride derivative in presence of base (Scheme 3).…”

“…This suggest that the reaction process through the cyclo-addition of carbon 2 and nitrogen 3 of the pyrido[2,3-d]pyrimidine thiones with the hydrazonoyl chloride derivative in presence of base (Scheme 3). 17 The reaction mechanism was postulated to start with S-alkylation of the…”

“…This result is in line with previous reports of the reactions of hydrazonoyl halides with similar condensed 2thioxopyridopyrimidines. [16][17][18][19][20][21]…”

A new one-pot synthesis of novel hetarylazo-heterocyclic colorants and study of their solvatochromic properties

“…A literature survey reveals that most of the reported hetarylazo heterocycles were usually prepared by coupling of diazotized heterocyclic amines with the appropriate heterocyclic nucleophilic reagents [1] or by reactions of hydrazonoyl halides with the appropriate reagents [2] . In continuation of our studies on exploring the utility of hydrazonoyl halides in synthesis of arylazo derivatives of heterocyclic compounds [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , it was thought interesting to study the synthesis of new 3-chloro-1,5- bis (hetaryl)formazans and explore their utility in synthesis of novel hetarylazo derivatives of various heterocycles. This is because, although 3-chloro-1,5-di-arylformazans, Ar—N N—C(Cl) NNHAr, have been known since 1946 [11] , [12] , [13] , little attention, if there is any, has been given hitherto to the related 3-chloro-1,5- bis (hetaryl)formazans of the general formula, Het—N N—C(Cl) NNH—Het.…”