Facile synthesis of novel polysubstituted thiopene and 1,3,4-thiadiazole derivatives

The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis

“…Phenacyl cyanides 311 [ 579 , 580 , 581 , 582 , 583 , 584 , 585 , 586 , 587 , 588 , 589 , 590 ] and phenacyl thiocyanates 312 [ 591 , 592 , 593 , 594 , 595 ] have been proven to be valuable tools for the synthesis of a wide variety of heterocyclic compounds. They are simply prepared via the reaction of α-haloketones with alkali metal cyanides and thiocyanates, respectively (Eq 7).…”

Simple and convenient routes to new polyheterocycles incorporating pyrazole, thiazole, thiophene, and 1,3,4‐thiadiazole moieties

“…The IR spectra of the products 14a-i exhibited, in all cases, the presence of nitrile, amide-NH, and carbonyl stretching SCHEME 3 bands near 3390, 2200, and 1680 cm −1 , respectively. Formation of the 2,3-dihydrothiadiazole structures 14a-i is assumed to proceed via a mechanism analogous to that reported previously [3] (Scheme 3). Although loss of an ethanol molecule from the intermediates 13g-i leading to the formation of compounds 15 would seem to be easier than the loss of aniline leading to the formation of compounds 14; however the obtained results showed that reaction of the thioacetanilide derivative 3 with ␣-ketohydrazonoyl halides 12a-i proceeds in the same manner, regardless of the type of hydrazonoyl halide used.…”

“…Recently, our research program has utilized some reactive-sulfur containing intermediates as versatile building blocks for the synthesis of several thiophene, thiazole, and 1,3,4-thiadiazole derivatives [1][2][3]. In this context, we report herein a convenient route to a variety of polyheterocyclic ring systems incorporating an antipyrin moiety via the reaction of the cyanothioacetanilide derivative 3 with some ␣-halocarbonyl compounds and halohydrazone derivatives.…”

Hydrazonoyl halides: Useful building blocks for the synthesis of arylazoheterocycles

“…Reactions of hydrazonoyl halides of type 2, 5A with potassium salts of active methine thioanilides were first reported to give the respective 5-arylazothiazoline derivatives 47 (Scheme 17) [38,39]. Although the latter products were said to be identified by alternate synthesis by coupling of diazotized anilines with the respective thiazoline derivatives 48, other literature reports indicated that reactions of active methine thioanilides with the same hydrazonoyl halides 2 and 5A as well as other hydrazonoyl halides 5B, 6B,G, 10B, B, 6B,G, 10B and 14A,B proceed via elimination of an arylamine from the initially formed thiohydrazonate esters 46 to give the respective thiadiazoline derivatives 49 (Scheme 17) [40][41][42][43]. Similar reactions of cyclic active methine thioanilides with hydrazonoyl halides 2, 5A,C, 6B, 10B and 12 were reported to yield the respective thiadiazoline derivatives 50 (Scheme 18) [44].…”