Thiosemicarbazones hydrazones

A large number of glycosulose l-(2-substituted) hydrazones have been prepared by Henseke and coworkers from the osazones by action of nitrous acid. These products, such as (89), were then treated with other substituted hydrazines, to give mixed osazones," or with hydrazine and other carbonyl reagents, to obtain ketazines and azines" hydrazone thiosemicarbazones, and hydrazone oximes. ... 

Recent studies have been directed towards the synthesis of heterocyclic hydrazones which have lower toxicities than thiosemicarbazones [44], It has been proposed that the hydrazinic N-H group is essential for activity since it might be involved in a crucial radical formation step important in the mechanism of RDR. This is supported by the loss of antileprotic activity for this series of compounds when the hydrazinic hydrogen is replaced by a methyl group [44]. The heterocyclic hydrazones, like thiosemicarbazones, behave as tridentate ligands. 

High chemoselectivities (up to 96%) were reached in the hydrogenation of phe-nylacetylene to styrene (DMF, 30 °C, 1 atm H2 pressure, 1% catalyst loading, TOFs up to 4.2 h-1) catalyzed by chloride Pd(II) complexes [Pd(NN S)Cl] containing thiosemicarbazone or thiobenzoylhydrazone ligands (5 in Scheme 4.5) [45]. Instead, minor reactivities and selectivities were obtained with NN N" pyridyl-hydrazone-containing Pd(II) complexes in the hydrogenation of phenylacetylene [46]. 

Isatin-3-hydrazones react with aldehydes to give 91.157,314 Compound 91 (R = H, Ar = 2-(5-nitrofuryl)) has also been prepared by reaction of isatin with 5-nitrofurfuraldehyde hydrazone.314 Ammonium isothiocyanate, and 86 gave isatin-3-thiosemicarbazones.318... 

The semicarbazone (96a), thiosemicarbazone (96b) and 2,4-dinitrophenyl hydrazone (96c) were all reacted with SOCl2 to yield 9//-l,2,3-thiadiazolo[4,5-a]-4,5,6,7-tetrahydropyrrolizine (97) <83IJC(B)822>. The reaction of varying amounts of benzylamine with 4-bromomethyl-5-benzoyl-1,2,3-thiadiazole (98) gave 5-benzyl-6-phenylpyrrolo[3,4-d]-1,2,3-thiadiazole (83) in low yields <78JHC473>. 

Disubstituted 4-phenyl-5-phenylimino-l,3,4-thiadiazolines (203 X = NPh) are prepared by the reaction of phenyl isothiocyanate with ketonic phenylhydrazones in DMF in the presence of sodium hydride. Replacing the isothiocyanate with carbon disulfide leads to (203 X = S). Aliphatic aldehydes react similarly however, benzaldehyde phenyl-hydrazone furnishes the thiosemicarbazone which on thermolysis yields the thiadiazoline (204). The structures of these compounds are supported by detailed spectroscopic measurements (80JCS(P1)574>. 

Isatin hydrazones and thiosemicarbazones can also be used as substrates for the Mannich reaction, leading to functionalization at N- . Isatin-3-hydrazone reacts with 1,1-... 

As a result of the powerful oxidizing potential of benzeneseleninic anhydride, it is incompatible with the presence of a number of functional groups, although many common moieties are well tolerated. Thus, it has been shown to convert thiocarbonyl compounds such as xanthates, thiocarbonates, thioamides and thiones, and hydrazones, oximes, thiosemicarbazones and hydroxyhttnines, into the corresponding carbonyl compounds under relatively mild conditions. Furthermore, hydrazo derivatives are converted to the azo compounds. ... 

Homogeneous uncatalysed reactions (e.g. the formation of the Co-salicylaldehyde thiosemicarbazone complex, which requires the prior oxidation of Co(ll) to Co(lll)) are less markedly affected by US than are homogeneous catalysed reactions (e.g. the oopper-catalysed oxidation of 2,2 -dipyridylketone hydrazone by hydrogen peroxide). The yield of these reactions increases by 28 and 300%, respectively, relative to unsonicated blanks. 

Addition to the Carbonyl Group — The internal, cyclic hemiacetal formation is one of the illustrations of such addition. The H2N-X nucleophiles, with X being NH2 (hydrazine), NHAr (arylhydrazines), OH (hydroxylamine), NHCONH2 (semi-carbazide), NHCSNH2 (thiosemicarbazide), or alkyl (primary amine), produce hydrazones, arylhydrazones, oximes, semicarbazones, thiosemicarbazones, and alkyl imines (Schiff bases), respectively, following the following path 5.4 + 5.15 — 5.16 ->. .. -> 5.21. 

Starch dialdehyde condenses readily with amino amides2624 and diamines,2625 and forms oximes with hydroxylamine.2626 The reaction of starch dialdehyde with isoniazid, 4 -formacelanilide thiosemicarbazone, 4 - amin o b e n z a I de h y de thiosemicarbazone or thiosemicarbazone, produced the corresponding condensation products.613-615 617 2627-2629 Hydrazones were readily formed when hydrazine and its derivatives were blended with starch dialdehyde and acidified with acetic acid2543,2630 or simply on heating the reaction mixture.2631 Condensation of starch... 

The reaction of (1S,4S)- and racemic camphor thiosemicarbazone [(1S,4S)- and rac-CTSC] leads to the formation of trans- and c/.v-isomers of (1S,4S)- or racemic camphor 5,-fluoro-4 -hydroxy-4, 5 -di(perfluoroalkyl)-l,3,-thiazolinyl-2/-hydrazones 211a-c and 213b,c (Scheme 189). The molecular structure of the two diastereomers (1S,4S,4 R,5 R)- and (1S,4S,4 S,5 S)- of 211a has been established by X-ray crystallography (03JFC(120)41). This result can be explained by a considerable contribution of the SN2 type of nucleophilic substitution both to the epoxide ring... 

The treatment of the 2-(4-chloromethylthiazol-2-yl)hydrazone of a heteroaromatic aldehyde (196) (formed as an intermediate in the reaction of some thiosemicarbazones with 1,3-dichloroacetone) with acetic anhydride gives rise to 3-hetaryl-substituted 2-acetyl-5-chloromethyl-2,3-dihydro-thiazolo[2,3-c][ 1,2,4]triazoles (197) (Scheme 17) <92JIC596>. 

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