Ureas seleno

Sheppard s early patent on sulfur sensitization (155) included sensitization by selenium compounds, such as seleno-ureas. He assumed that the two types of sensitization were... 

One of the more important uses of thioureas has been in the preparation of 2-imino-4-thiazolidinones, first reported by Meyer and Andreasch, " via reaction with a-halo acids or esters. This reaction has been covered by Brown in a review on 4-thiazolidinones which appeared in 19()1, and, therefore, will not be discussed in detail here. The corresponding reaction between a-halo acids or esters and seleno-ureas to produce 2-iminoselenazolidin-4-ones is also known and has been reviewed.Akerblom ° has attempted to clear up some of the confusion in the literature on whether 3-alkyl-2-iminothiazolidin-4-ones (63) or 2-alkylamino-2-thiazolin-4-ones (64) are formed from 1-alkyl-thioureas and chloroacetic acid. She found that the reaction in water... 

Freund and Wolf reported that 2,4-diphenyl-l,2,4-thiadiazolidine-3,5-dithione was formed by heating l,3-diphenyl-2-thiourea with thiophosgene in benzene whereas, a 1,3-thiazetidine was produced at lower temperatures in ether (see Section II). Chande has reported that 3,5-diamino-l,2,4-thiadiazoles are formed by the reaction of thiopseudoureas with carbon disulfide in the presence of bromine. Use has also been made of thioureas in the synthesis of 1,3,4-thiadiazolines (79) via reaction with the halohydrazones 78.The analogous reaction with seleno ureas was recently reported by Bulka and Ehlers to yield 1,3,4-selenadiazolines. 

Principal components of the 13C, 31P and 77Se shielding tensors were determined from solid-state NMR data for the complex [ (Me3P)Au(seleno-urea) 22+. 20 ].254... 

Review. Clive has reviewed new uses for this metal for synthesis of seleno-ketones, ureas, carbonates, formanilides, and carbamates (16 references). 

Seleno urea and an organic base has also been used as catalyst in the N-carbonyl at i on o-f aromatic nitro compunds to carbamates f303,30< Even MNCS are catalysts -for this reaction. ... 

Without additional reagents Thio- or seleno-ureas and thio- or seleno-semicarbazides from isonitriles... 

The reactivity of thioureas towards oxidants, however, has been more extensively studied. 1,3-Disubstituted thio- and seleno-ureas have been converted into the corresponding ureas by means of DMSO in the presence of an acidic catalyst. l,l-Dimethyl-3-phenylthiourea was oxidized by benzenesulphenyl chloride, thionyl chloride, sulphuryl chloride, and sulphur monochloride to the same product, (339). The oxidation of thioureas... 

Several recent papers deal with the restricted C—rotations in unsubstituted/" monosubstituted, NlsT-disubstituted, NN-disubsti-tuted, N,N,N -trisubstituted, " and tetrasubstituted " thioureas, together with the conformational aspects involved. The barriers to C—N rotation of thio- and seleno-urea were equal (AF = 12.8 kcal mol" ) and above that of urea (AF = 11,0 kcal mol" ). Restricted-rotation phenomena have been observed for substituted N-(tosylmethyl)thioureas, thiourea S-trioxides, " and 3-aryl-2-thiohydantoins. ... 

An ethanolic soln. of aniline added to a soln. of phenylisoselenocyanate in chloroform, and refluxed ca. 5 min. after the exothermic reaction has subsided N,N -diphenylselenourea. Y 96%. F. e., also unsym. and monosubst. selenoureas with NHg, s. E. Bulka, K.-D. Ahlers, and E. TuCek, B. 100, 1459 (1967) seleno- from thio-ureas cf. D. L. Klayman and R. J. Shine, Ghem. Gommun. 1968, 372. 

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