Reactions of the activated, rigid, α‐diazomethine group of 1,2,5‐thiadiazole 1,1‐dioxides with nitrogenated nucleophiles. Part III: aliphatic monoamines and phenylhydrazine

Abstract

The reactions of n-butylamine (BuNH 2 ), 2-aminoethanol (H 2 N(CH 2 ) 2 OH), diethylamine (Et 2 NH), and phenylhydrazine (PhN 2 H 3 ) with 3,4-diphenyl-(1a) and phenanthro[9,10-c]-1,2,5-thiadiazole 1,1-dioxide (1b) were studied by cyclic voltammetry (CV) and 1 H-and 13 C-NMR in aprotic solvent solution. The course of the reactions depended on the substrate-nucleophile combination: Et 2 NH added to 1a or 1b, forming the corresponding thiadiazolines in an equilibrium monoaddition reaction. The equilibrium constants were evaluated and compared. With primary amines and PhN 2 H 3 , the nucleophile added to both C --N double bonds of 1a and displaced the sulfamide moiety. In the case of the reaction of 1a with PhN 2 H 3 , the intermediate monoaddition thiadiazoline, 3-(2phenylhydrazino)-3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide, was also isolated. BuNH 2 and H 2 N(CH 2 ) 2 OH reacted with 1a to give a-bis-imines, while 1a with PhN 2 H 3 gave the a-bis-hydrazone. The configurations of benzil bis(ethanolimine) and benzilosazone were determined by single crystal x-ray diffraction analysis as Z,Z. BuNH 2 and PhN 2 H 3 reduced 1b to the corresponding thiadiazoline compound 1bH 2 . EXPERIMENTALCompounds 1a, b were synthesized according to Wright. 7 Standard methods 8-10 were used for purification of commercial solvents and nucleophiles. The solvents were JOURNAL OF PHYSICAL ORGANIC CHEMISTRY

On experimental versus theoretically calculated properties of thiadiazole derivatives

“…Adding to the evidence already available [4], we have recently reported that the initial reactions of o-phenylenediamine with 2, and ethylenediamine with 1 or 2 [7], diethylamine with 2 [8], or thiourea with 1 [10], are all additions to the heterocyclic C-atoms, thus supporting the theoretical results for 2, but only the new CHIH-DFT prediction for 1 (Table II).…”

1,2,5-Thiadiazole 1,1-dioxides and Their Radical Anions: Structure, Properties, Reactivity, and Potential Use in the Construction of Functional Molecular Materials

“…This has proven to be a general reactivity of 3,4-substituted-1,2,5-thiadiazole 1,1-dioxides toward alcohols; many examples of addition of primary and secondary alcohols were presented and described in details, providing equilibrium constants for these reactions [ 68 ]. The same equilibrium and addition to double C=N bond can be observed for primary/secondary amines and amides; see Figure 5 [ 85 , 86 ].…”

“…Products of such additions are not stable and exist only in solution. However, for some nucleophiles, this reversible addition to both C=N double bonds may lead even to an irreversible ring cleavage with the release of sulfamide molecules when the reaction is carried out in anhydrous MeCN or DMF at room temperature; see Figure 6 [ 85 , 87 ]. Double additions can also be achieved using urea (or thiourea) and its substituted analogues to furnish the bicyclic products presented in Figure 7 [ 73 , 86 ].…”

Radical anions containing the dioxidated 1,2,5‐thiadiazole heterocycle

“…Ethylenediamine (not included in the table) does not give radicals but adds to the double bonds of thiadiazoles,22 and, following the elimination of sulfamide, yields the corresponding dihydropyrazines. We have reported5–8, 11, 13, 23, 24 the addition reaction to one or both CN double bonds of 1 ‐compounds of a number of nucleophiles. It was considered reasonable that nucleophilic addition reactions, followed or not by decomposition of the addition product, were the cause of the lower %S.…”

“…We have studied the structure and some physicochemical properties of several known members of this family of compounds, as well as those of many new ones synthesized in our laboratory 5–13…”