Thiosemicarbazones thiourea

Type D synthesis, where the 3,4-CN bond is being formed, involves the reaction of thiosemicarbazones of aldehydes, ketones, and esters 97 with 3,3-pentamethyleneoxaziridine 98 to afford 5-imino-3,3-pentamethylene-l,2,4-thiadi-azolidines 99 (Equation 27). yV-Acylthioureas also undergo this transformation but, whereas this reaction is fairly general for thiosemicarbazones, only acetyl and benzoyl thioureas give 1,2,4-thiadiazolidines <1996CHEC-II(4)307>. There have been no new reports of type D syntheses since the publication of CHEC-II(1996). 

Thiosemicarbazones, such as 331, and thiourea (333) give rise to sulfinic acids when subjected to photosensitized oxygenation reaction conditions.62,233 It was suggested that by analogy to olefin oxygenation the primary products may be of hydroperoxidic nature... 

Azine approach. Vicinal dihalides with the halogens in activated azine positions will react with thiourea or thiosemicarbazone to form thiazoles as in the reactions of 2,3-dichloroquinoxaline (77ZC15). 

Many organic spectrophotometric reagents for Pd incorporate sulphur as a ligand atom. Apart from dithizone and thio-Michler s ketone, which have been discussed above, examples include the thiourea derivatives [33-36] p-dimethylaminobenzylidene-rhodanine (rhodanine) (e = 4.9 10 ) [37] and its derivatives [38], thiodibenzoylmethane [39,40], and thiosemicarbazone derivatives [41—47]. 

X-ray crystal structures, 397 tetrakis(perfluoroalkanesulfonates), 418 tetraphenylporphyrin, 440 thioacetylacetonato, 439 thiocyanates, 380 thioethers, 418 thiolates, 418 thiosemicarbazones, 434 thiourea, 421 tin-containing ligands, 370 trialkyIsilyloxides, 389,391 triazenes, 378 triethylamine, 371 trihydroxyglutaric acid, 412 tris(diketonates), 399 tropolonates, 402 urea, 382 water, 384... 

This reaction was first reported by Hantzsch and Weber in 1887. It is the formation of thiazole derivatives by means of condensation of a-haloketones (or aldehydes) and thioamides. Therefore, it is generally known as the Hantzsch thiazole synthesis. In addition, other names, including the Hantzsch synthesis, Hantzsch reaction, and Hantzsch thiazole reaction are also used from time to time. Besides thioamides, other thio-ketone derivatives such as thiourea, dithiocarbamates, and ketone thiosemicarbazone can also condense with a-halo ketones (or aldehydes) to form thiazoles. This reaction occurs because of the strong nucleophilicity of the sulfur atom in thioamides or thioureas, and normally gives excellent yields for simple thiazoles but low yields for some substituted thiazoles, as of dehalogenation. This reaction has been proven to be a multistep reaction, and the intermediates have been isolated at low temperatures, in which the dehydration of cyclic intermediates seems to be the slow step. It is found that a variety of reaction conditions might result in the racemized thiazoles that contain an enolizable proton at their chiral center, and it is the intermediate not the final product that is involved in the racemization. Therefore, some modifications have been made to reduce or even eliminate the epimeriza-tion upon thiazole formation. In addition, this reaction has been modified using a-tosyloxy ketones to replace a-haloketones. ... 

Monosubstituted thioureas give, in this reaction, a mixture of the isomeric 2-imino-4-thiazolidinones (196) and (197), the former predominating. Similarly, dithiocarbamates, thiocarbamates, thiosemicarbazides, and thiosemicarbazones give analogous 4-thiazolidinones of type (198) and (199), which were further studied. ... 

Irradiation of 2-methyl-4-phenyl-substituted benzaldehyde thiosemicarbazones (171) leads to the corresponding A -l,2,4-triazohne-5-thione derivatives (173) through the formation of stable 1,2,4-tria-zoHdine-5-thione derivatives (172) (Scheme 27). Irradiation of N-acylthiourea (174) in the presence of triethylamine gives thiourea (175) and benzothiazoles (176) via an electron-transfer mechanism. A photochemicaUy induced Dimroth rearrangement has been reported in the l,2-thiazolino[5.4-d]-l,2-thiazoline-3,6-dithione (177) and yields the 3ff,6ff-l,2-dithiolo[4.3-c]-l,2-dithiole (178). ... 

Derivatisation reagent for carboxylic acids for hplc anal. Anal, reagent for thioureas and thiosemicarbazones. Prisms (EtOH aq.). Mp 51°. Bp,8 135°. 

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