Syntheses from Dithiocarbazates

Syntheses from Dithiocarbazates. A novel variant of the general synthesis of 2-aryl-5-mercapto-l,3,4-thiadiazoles from dithiocarbazates (107) derived from carbon disulphide and (thio)benzhydrazides (106 X = S or or benzhydrazoximes (106 X = NOH) involves the use of benzimidrazones 

The interaction of dithiocarbazic esters and bromocyanogen in aqueous potassium bicarbonate produces good yields of 2-amino-5-alkylthio-1,3,4-thiadiazoles. The reaction is an extension of the known synthesis of the 5-alkoxy-analogues from alkoxythiocarbonylhydrazines and bromocyanogen.  

Kubota, Y. Koida, T. Kosaka, and O. Kirino, Chem. and Pharm. Bull. Japan), 1970, 18, 1696. 

The reaction between hydrazinium ditliiocarbazates and aliphatic aldehydes or ketones yields 5,5-disubstitutcd l,3,4-thiadiazolidine-2-thiones (111). Treatment of (111) with potassium hydroxide or methyl iodide leads, in some cases, to ring fission, with formation of the salts or methyl esters of alkylidenedithiocarbazic acids (112). I.r., n.m.r., and mass spectra 

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The synthesis of l,3>4-thiadiazolinones from dithiocarbazic esters and phosgene [(110)->(111 Ac = H)] is applicable to 3-acylated thio- and... 

The synthesis of a series of thiazolo[2,3-c][l,2,4]triazole derivative 33 has been approached by base-mediated intramolecular cyclization of bromide 349 or acid-promoted ring closure of alcohol 350, obtained from pyrazinoyl-dithiocarbazate 348 (Scheme 33) <2004PS(179)2519>. 

A general method has been reported for the parallel solid-phase synthesis of 1,2,4-triazole derivatives based on the cyclization of polymer-bound dithiocarbazate 42 (by a two-step sequence from Fmoc-hydrazine) with electrophiles using a similar route to the formation of pyrazole 7." The linker 42 served as a nucleophile for the cyclization reactions with electrophiles such as cyanocarboimidates 46 (R diversity elements) (Scheme 10.11). 

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