1,3,4-Oxadiazolium-thiolat

Substituted tetrazoles reacting in the mass spectrometer with acyl ions afforded 2,5-disubstituted 1,3,4-oxadiazoles with nitrogen loss. Tandem mass spectrometry allowed for the collision-induced dissociation of the products. Chemical ionization was the better method to make the transformation. A scheme for the transformation of 5-substituted tetrazoles into 2,5-disubstituted 1,3,4-oxadiazoles was proposed (Scheme 1) <2001JMP1069>. The fragmentation patterns of monocyclic l,3,4-oxadiazolium-2-thiolates have been proposed by Ollis and Ramsden <1974J(P1)645>. 

Durch Cyclisierung von 1-substituierten Carbonsaure-hydraziden mit Schwefelkohlenstoff in Gegenwart von Dicyclohexyl-carbodiimid oder besser von Diethyl-carbodiimid erhalt man mesoionische 4,5-disubstituierte 1,3,4-Oxadiazolium-2-thiolate. Diethyl-carbodiimid ist trotz seiner schlechteren Lagerfahigkeit fur diese Reaktion zu empfehlen, weil die Aufarbeitung der Reaktionsprodukte erleichtert und die Ausbeute damit gesteigert wird221. 

The novel fused mesoionic l,3,4-oxadiazolium-2-thiolates 24 can be synthesised from A -amino-./V7V" -dihydrodiazinediones by treatment with carbon disulfide in the presence of DCCI <97H(45)2101>. 

Meso-ionic 1,3,4-Thiadiazoles.—The synthesis and properties of isomeric pairs of l,3,4-thiadiazolium-2-olates (128) and of l,3,4-oxadiazolium-2-thiolates (127) have been described, thus establishing the existence of isomeric meso-ionic compounds, the interconversion of which [(127) (128)] involves an exchange... 

OEthyl thionocarbamates have been obtained by ethanolysis of 1,3,4-oxadiazolium-2-thiolates, and S-alkyl N-(o)-mercaptoalkyl)-dithio-carbamates were produced by rearrangement of S-alkyl S -(o)-amino-alkyl)trithiocarbonates." Limitations in space preclude a discussion of the many papers reporting on the syntheses of a variety of heterocyclic compounds containing the thionocarbamate " or the dithiocarbamate (refs. 244, 418, 419, 513, 651, and 659—664) grouping. 

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