2- phenyl selenourea

There are amines such as A-methylnitroamine, that are too weakly nucleophilic to be able to form covalent adducts with arenediazonium ions. The products of the latter appear to be those of salts ArNJ N(N02)CH3, as found by Baranchik et al. (1957). Amides also appear not to be sufficiently nucleophilic, but thioamides are, as is shown by the reaction of A-phenylthiourea in the presence of NaOH (Scheme 13-12 Nesynov et al., 1970). First a (probably homolytic) phenylation-de-diazoniation takes place, followed by A-coupling. Selenourea also reacts a mixture of products is formed, which indicates a reaction of the same type as with thiourea (Nesynov and Aldokhina, 1976). 

General methods for preparation of imidazolidin-4-one-2-thiones include the reaction of thioureas with a-dicarbonyl compounds,37,38 with ethyl phenylpropiolate,39 and with phenyl chlorothiolacetate,40 and cyclization in acid of l-(carbethoxymethyl)-2-thioureas.41 The analogous reaction of a-diearbonyl compounds with selenoureas produce imidazolidin-4-one-2-selones.42 Berlin and Levi43 utilized the acid-catalyzed cyclization of l-aryl-3-carbalkoxymethyl-2-thioureas to produce 3-arylimidazolidin-4-one-2-thiones (23). 

The reaction of l-alkyl-3-arylthioureas (or selenoureas) with a-halo esters in the presence of base has been claimed to produce 3-alkyl-2-aryliminothiazolidin-4-ones141-143 (and the selenium analogs).144 However, Omar145 recently reported that a l-benzyl-3-phenyl-2-thiourea, when treated with ethyl bromoacetate produced a thiazolidi-none which has the alkyl side chain on the exo nitrogen, i.e., the 3-aryl-2-benzyliminothiazolidin-4-one. 

Oxidation of l-phenyl-2-selenourea with bromine affords 2-aminobenzoselenazole (69). 

Treatment of the 1 1 complexes between phenyl tellurium bromide and ethylenethio- or -selenourea with sodium iodide in warm methanol yielded the corresponding phenyl tellurium iodide complexes5. 

A similar exchange reaction produced the 1 1 complexes of phenyl tellurium thiocyanate with ethylenethiourea1, when the phenyl tellurium chloride complex was treated with potassium thiocyanate in aqueous methanol. However, the phenyl tellurium chloride -selenourea adduct and potassium selenocyanate yielded bis[phenyIteUuro] selenium3. Phosphane selenides also coordinate to phenyl tellurium halides3. 

Reports on the crystal structure of selenourea rqrpeared in the early 1960s, which gave preliminary accounts of the unit-cell dimensions of selenourea [5]a,b] and information about the carbon-selenium double bond in the crystal structure of /V-phenyl-AT-benzoylselenourea [57c]. More accurate determination of the lattice parameters and atomic positions of selenourea was carried out at room temperature and at 173 K by Rutherford and Calvo in 1969 [52]. All of these reports assigned the structure to one of the enantiomorphous trigonal space groups P3 and P32 with Z=27, which differs from an earlier electron diffraction study based on space group Pnma with a = 6.48, b = 8.75, and c = 7.04 A and Z=4 [55a] that can be compared with the room-temperature phase of thiourea. The lattice parameters of selenourea firom these studies are listed in Table 6. 

Ligand abbreviations su = selenourea esu = ethyleneselenourea tu = thiourea ph = phenyl. 

Phenylurea added to a soln. of startg. furan-2,3-dione in glacial acetic acid, and heated for 1 h - 3-phenyl-5-phenacylideneimidazolidine-2,4-dione. Y 79%. F.e. and 2-thioxo- and 2-selenoxo-analogs from thioureas and selenoureas, respectively, s. Y.S. Andreichikov et al., Khim. Geterotsikl. Soedin. 1988, 1411-3. 

More exotic thioureas were the products of interesting reactions of isothiocyanates with ketimines, enamines imino-esters/ amidines, amidrazones, and substituted ammonium salts. Some selenoureas have been synthesized by the reaction of isoselenocyanates with amines, and the phosphorus compounds (300) were obtained analogously by treatment of w-mercaptoalkylphenylphosphines with phenyl isothiocyanate. The action of primary amines on (300) resulted in the formation of N-alkyl-lsT-phenylthioureas in high yields with simultaneous regeneration of the w-mercaptoalkylphenylphosphine. ... 

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