Thiourea derivative

In addition to ureas, several thiourea derivatives are described in the patent literature generally, however, they have weak effects. Of the experimental herbicides, l,l-dimethyl-3-(3-methyiphenyl)thiourea (methiuron, 45) and l-(4-chlorophenyl)-3-methyl-3-phenyl)thiourea (Ortho 11413, 46) seem to be promising. 

Owing to the greater nucleophilic character of sulfur relative to oxygen, reaction of 1,3-disubstituted thioureas with phosgene usually occurs at the sulfur atom, to give high yields of chloroformamidinium chlorides [2083a, 2087]  

In a non-polar solvent, which retards the elimination of COS, it is possible to isolate the initial reaction product [585]  

Significant formation of allophanoyl chlorides, RNHC(0)NR C(0)C1, does not take place. Further, the formation of the gaseous co-product COS gives this reaction a considerable advantage over the corresponding use of phosphorus(V) chloride, the co-product, liquid P(S)Cl3, being very difficult to remove [2083a]. 

Reaction of thioureas with phosgene is usually performed at room temperature in an inert solvent (such as benzene, chlorobenzene or 1,2-dichloroethane) in which the thiourea is soluble. By-products, if formed, are readily separated with ethoxyethane in which the chloroformamidinium chloride salts are insoluble. 

The loss of two molecules of HCl (often at room temperature) from the chloroformamidinium salts results in the formation of carbodiimides, RN=C=NR [2087,2087a]. The use of an excess of COClj should therefore be avoided, since carbodiimides themselves can react with phosgene to give chloroformamidine-iV-carbonyl chlorides, see Section 10.2.8. Indeed, in early work [2189a], diarylthioureas were found to react with an excess of COClj to form cyclic compounds  

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Thiourea dioxide, or formamidine sulfinic acid, is an oxygenated thiourea derivative synthesized by the oxidation of thiourea with hydrogen peroxide. It has the chemical formula (NH2)NHCS02H and is tautomeric. 

Aryl-substituted thiourea derivatives (thiocarbamide derivatives) [4] ... 

Lead(II) acetate yields colored lead salts with flavonoids and thiourea derivatives. 

If the acid hydrolysis of 1,3-oxazine derivatives is followed by acting with phenyl-isothiocyanate, thiourea derivatives can be formed. ... 

N-(2,6-dichiorophenyl)thiourea (MP 149°C) was prepared in customary manner from 2,6-dichloroaniline (Organic Synthesis lil, 262-263) and ammonium thiocyanate. 16.0 g of this thiourea derivative were refiuxed for 2 A hours together with 16 g of methyl iodide in 150 cc of methanol. Thereafter, the methanol was evaporated out of the reaction mixture in vacuo, leaving as a residue 22 g of N-(2,6-dichlorophenyl)-S-methyl-isothiouronium hydroiodide of the formuia... 

Figure 11.4 shows the relationship between efficiency and concentration of some thiourea derivatives and gelatin in the pickling of cold-reduced and annealed strip in 6% w/w sulphuric acid at 85°C. The thiourea derivatives, diluted with sodium chloride, gelatin and a wetting agent, are used commercially. Mono- and di-o-tolyl thioureas are stable in this pickle for at least 50 h, but diphenyl thiourea and gelatin decompose after four or five hours. 

The mass spectra of primary mono- and diaminoquinoxalines (with or without additional C-methyl groups) have been measured and analyzed. The role of N-pyridinyl-A -(quinoxalinylethyl)thiourea derivatives as HIV-1 (human immunodeficiency 1) reverse transcriptase inhibitors has been discussed in detail. 

The amino acids probably react with the fluorescein isothiocyanate to yield fluorescein thiourea derivatives. These are hydrolyzed at elevated temperature in alkaline medium so that the amino groups that are produced can then react with ninhydrin. 

Sulfur-containing compounds [1-3] e.g. thiols [4, 5] and thioethers [5] sulfide ions [4] thiourea derivatives... 

Chiral amines and diamines are readily available substrates for the synthesis of ligands for transition metal-catalysed reactions since they can easily be transformed into chiral ureas and thioureas. Therefore, several groups have prepared chiral symmetrical ureas and thioureas, dissymmetrical ureas and thioureas, amino-urea and thiourea derivatives. Finally polyureas and non-soluble polythioureas were also prepared and tested as ligands for asymmetric catalysis. 

Moreau and co-workers have also prepared (ll ,2K)-l,2-diaminocyclo-hexane amino-urea and thiourea derivatives [43]. Diphenylethylenediamine-substituted monothioureas are more stable than the cyclohexyldiamine counterpart, but they can also rearrange to guanidine derivatives, especially at high temperature or in the presence of metal [43]. Under the same conditions, thioureas also rearrange to guanidines in the presence of amines. Selective formation of substituted guanidines from thiourea derivatives of diaminocy-clohexane or diphenylethylenediamine were also reported in a recent paper from Ishikawa [44]. 

Non-ionic thiourea derivatives have been used as ligands for metal complexes [63,64] as well as anionic thioureas and, in both cases, coordination in metal clusters has also been described [65,66]. Examples of mononuclear complexes of simple alkyl- or aryl-substituted thiourea monoanions, containing N,S-chelating ligands (Scheme 11), have been reported for rhodium(III) [67,68], iridium and many other transition metals, such as chromium(III), technetium(III), rhenium(V), aluminium, ruthenium, osmium, platinum [69] and palladium [70]. Many complexes with N,S-chelating monothioureas were prepared with two triphenylphosphines as substituents. 

The reaction was first tested with these substances as ligands but the organic molecule, in the absence of any added metal ion, proved to be the most enantioselective catalyst (library 1 19% ee vs. less than 13% ee for the best metal catalyst). The effects of selective variations of the amino acid nature and of the salicylidene moiety on the diamine structure were investigated for urea and thiourea derivatives via HTS (library 2 48 urea compounds and... 

Finally, nitrone cyanation were performed with non-chiral urea and thiourea derivatives, the latter being more efficient for this process. No chiral compound has been described yet (Scheme 41) [ 159]. 

New catalysts were prepared after optimisation of the Ugand structure. The most efficient organo catalyst for this reaction was an amido-thiourea derivative (Scheme 43). Interestingly, dissymmetrical ligands were more efficient and selective for this reaction. 

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