Thiadiazoline 1,1-dioxides

Purer product can be obtained by reducing 1,2,3-benzothiadiazole 1,1-dioxide with zinc and acetic acid to 1,2,3-benzo-thiadiazoline 1,1-dioxide, which is oxidized back with lead tetraacetate.5... 

Methyl-4-phenyl-l,2,5-thiadiazole 1,1-dioxide 21 suffers proton abstraction in basic nonaqueous media to give a resonance stabilized anion 43, neutralization of which using anhydrous TFA gives the orange tautomer 4-methylene-3-phenyl-l,2,5-thiadiazoline 1,1-dioxide 44 (Scheme 3) <2001JP0217>. The tautomeric equilibrium is practically displaced toward 21 in acetonitrile and toward 44 in DMF. 

A difference in reactivity was observed between the phenanthro[9,10-r]- and acenaphtho[l,2-c]-l,2,5-thiadiazole 1,1-dioxides 51 and 53 when treated with thiourea. The acenaphtho derivative 53 gave the expected addition product however, the phenanthro thiadiazole 51 was reduced to the thiadiazoline 1,1-dioxide 52 (Equation 2) <2004JP01091>. The difference in reactivity was attributed to the enhanced resonance stability offered by the phenanthrene group. 

Electrochemical reduction of various 3,4-disubstituted-l,2,5-thiadiazole 1,1-dioxides (3,4-diphenyl- 10, phenanthro[9,10]- 51, and acenaphtho[l,2]- 53) gave the corresponding thiadiazoline 1,1-dioxides <1999CJC511>. Voltammetric and bulk electrolysis electroreduction of 3,4-diphenyl-l,2,5-thiadiazole 1-oxide 9 at ca. —1.5 V, in acetonitrile, gave 3,4-diphenyl-l,2,5-thiadiazole 8 (50%) and 2,4,6-triphenyl-l,3,5-triazine 54 (30%) (Equation 3) <2000TL3531>. 

Stereoselective hydride reduction of 1,2,5-thiadiazoline 1,1-dioxides 60 generates unsymmetrical 1,2,5-thiadiazol-idine 1,1-dioxides 61 <1998SL623> that can be readily converted to unsymmetrical vicinal diamines 62 with HBr in the presence of phenol (Scheme 5) <1996TL2859, 1998SL623>. The unsymmetrical thiadiazolidine 1,1-dioxides 63 can also be converted into 1,2-diketones 64 on treatment with selenium dioxide followed by alkaline hydrolysis (Equation 7) <1997SL671>. 

Strong acid hydrolysis of 1,2,6-thiadiazine 1,1-dioxides 239 or 240 results in ring contraction to afford the 1,2,5-thiadiazolinone 1,1-dioxides 241 in low yield <1996J(P2)293>. 3-Dialkylamino-2/7-azirines 242 suffer ring expansion with in situ-prepared iV-sulfonylamides 243 and carbamates to give both the 1,2,3-oxathiazoline 244 and the thiadiazoline 1,1-dioxide 245 (Equation 56). The oxathiazole 244 isomerizes quantitatively to the thermodynamically favored thiadiazoline 245 <1996J(P1)1629>. 

A -1,3,4-Thiadiazoline-1 -oxides (146) (Equation (18)) are formed by addition of diazo compounds (R2C=N2) to sulfines (R R C =S=0). The adducts from diazomethane and aryl substituted sulfines are unstable and give the thiadiazole (147) via a Pummerer-type aromatization <84CHEC-I(4)545>. The A -thiadiazoline-1,1-dioxide (149) has been produced by oxidation of the hydrazone (148) (Equation (19)) and treatment with sulfur dioxide <84CHEC-i(4)545>. 2-Alkylidenethiadiazolines can be obtained from the dipolar addition of diazo compounds to thioketenes <83CB66, 90TL3571, 92HCA1825>. 

Alcohols, thiols, amines, and amides add reversibly in aprotic solvent to one of the two C=N bonds of 3,4-disubstituted-l,2,5-thiadiazole 1,1-dioxides to give the corresponding thiadiazoline 1,1-dioxides <1996CJC1564,... 

The direct formation of disubstituted l,2,5-thiadiazole-l,l-dioxides (57) by condensation of a-diketones with sulfamide was reported by Wright and by Vorreither and Ziegler. The 1,2,5-thiadiazoline-1,1-dioxides (58) were prepared by a similar method employing a-hydroxy ketones. Hydrogenation of both 57 and 58 over Adams catalyst provided the corresponding disubstituted 1,2,5-thiadiazolidine-1,1 -dioxides (60). 2-Alkyl-l, 2,5-thiadiazoline-l, 1-... 

Following a rather similar procedure, the reaction of benzoins with sulfamides afforded the thiadiazoline 1,1-dioxides 103 (64JOC1905). 

Furthermore, according to the publication, pesticide activity can be inferred for some thiadiazoline 1,1-dioxides prepared by authors in the Soviet Union (75M11). 

Thiadiazoline 1,1-dioxides (e.g., 328, 331) are obtainable by the cyclization by alkali of the readily accessible N-(iodomethylsulfonyl)benz-... 

Stirred at 0° with iodomethane-sulfonamide in dimethylform-amide and ethanolic Na-ethoxide added, the product isolated after 2 hrs. at 0° -> 4-o-tolyl-3-o-tolyl-amino-d2.i 2,4-thiadiazoline 1,1-dioxide. 

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