Synthesen mit 2,4‐Dimethylen‐1,3‐dithietanen. Mercaptopyridine; Thiazole; Dithiole; mesoionische und nichtmesoionische 1,2,3‐Thiadiazole

Abstract

Die aus den 2,4-Dimethylen-l,3-dithietanen 1 in situ erzeugten Thioketencarbonsaureester 6 cyclokondensieren mit Aminocrotonsaure-Derivaten 5 zu den 4-Mercaptopyridinen 4, mit Glycinbzw. Thioglycolsaureester 7 zum Alkylidenthiazolidin bzw. Alkyliden-l,3-dithiolan 8. Dagegen findet rnit Diazoalkanen 1,3-dipolare Cycloaddition statt, wobei in einem Arbeitsgang die noch nicht beschriebenen mesoionischen und nichtmesoionischen 5-Methylen-l,2,3-thiadiazole 10 bzw. 9 gebildet werden.Syntheses with 2,4-Dimethylene-1,3-dithietanes. Mercaptopyridines; Thiazoles; Dithioles; Mesoionic and Non-mesoionic 1,2,3-ThiadiazolesThe thioketene carboxylates 6, generated in situ from 2,4-dimethylene-l,3-dithietanes 1, undergo cyclocondensation with aminocrotonic acid derivatives 5 to give the 4-mercaptopyridines 4, whereas with the esters 7 of glycine and thioglycolic acid the alkylidenethiazolidine and alkylidene-l,3-dithiolane 8, resp., are formed. In contrast, with diazoalkanes 1,3-dipolar cycloaddition take5 place to yield the not yet described mesoionic and non-mesoionic 5-methylene-1,2,3-thiadiazoles 10 and 9, resp., in one operation.

(E)-2-[(1,2,3-Thiadiazol-5-yl)iminomethyl]phenol

“…The bonding about S1 is slightly asymmetrical ( Table 1). The remaining bond lengths and angles of ring A are in agreement with values reported for similar structures (Capuano et al, 1983).…”

HI/DMSO‐Catalyzed Cyclization of Aryl(sulfo)acylhydrazones with Sulfur

“…Some mechanistic studies on the reaction of N ‐tosylhydrazones with S 8 have been reported . Herein, we propose a possible catalytic cycle of arylketoacylhydrazones with S 8 .…”

“…As an important heterocyclic compound, 1,2,3‐thiadiazole has been widely used in medicine, pesticides and organic synthesis due to its unique biological activity and inherent reactivity (Figure ). Traditional methods for constructing 1,2,3‐thiadiazole skeletons include the followinng four types: (a) Hurd‐Mori synthesis; (b) heterocyclization of α ‐diazo thiocarbonyl compounds (Wolff Synthesis); (c) cyclization of diazoalkanes onto a C=S (Pechmann Synthesis); and (d) other cyclization methods . However, there are some disadvantages in the above methods, such as the use of substrates that are not easily available, a narrow substrate range, and harsh reaction conditions.…”

Synthesis of 4‐Aryl‐1,2,3‐Thiadiazoles via NH4I‐Catalyzed Cyclization of N‐Tosylhydrazones with Sulfur

“…At the same time, it is widely used as a useful organic intermediate in synthetic chemical reactions . In general, the synthesis of 1,2,3‐thiadiazole mainly includes the following aspects: (a) diazotized α‐aminoketones react with Lawesson reagents; (b) the Hurd−Mori reaction; (c) the reaction of diazomethane with phenyl isothiocyanate; (d) 1,3‐dipolar cycloaddition of diazoalkanes to thiocarbonyl compounds; [3+2] cycloaddition of α‐enolic dithioesters with tosyl azide; and (f) the reaction of lithium (trimethylsilyl)diazomethane with thiocarbonyl compounds . However, these methods developed often suffer from limitations including potentially explosive materials(the diazo compounds and azide), require air‐sensitive reagents(SOCl 2 , and SCl 2 ), harsh reaction conditions, and narrow substrate scope.…”