Reaction of diphenylselenium dimethylate, obtained in situ from diphenylselenium dichloride (I), with the amides (II) produces the selenilimines (III).
A 3:1 molar mixture of the tellurium imines (I) and diphenyl ditelluride (II) reacts to give a separable mixture of the diaryl tellurides (III), the sulfonamides (IV) and the N,N‐bis(phenyltellurenyl)sulfonamides (V).
SHORT COMMUNICATIONSAromatic compounds having an amino group and a tellurium-containing moiety in the ortho positions with respect to each other are promising synthons for the preparation of tellurium heterocycles with two heteroatoms; they can also be used as soft ligands for the synthesis of coordination compounds. Up to now, only two methods for the synthesis of such amino tellurium compounds have been reported. Bis(2-aminophenyl) ditelluride [1] was synthesized in three steps including mercuration of azobenzene at the ortho position; reaction of the chloromercurio derivative thus formed with tellurium tetrachloride to obtain 2-(phenylazo)phenyltellurium trichloride; and treatment of the latter with NaBH 4 , which resulted in simultaneous reduction of the trichlorotellurium moiety to ditelluride and of the azo group to amino. The other method for the synthesis of bis(2-amino-5-R-phenyl) ditellurides is based on mercuration of para-substituted anilines, followed by reaction of 2-chloromercurio-4-R-anilines with TeBr 4 and reduction of the resulting tellurium tribromides with hydrazine hydrate [2]. However, these procedures are not free from some disadvantages. In particular, intermediate products in each step should be thoroughly purified, and the overall yields of the target products do not exceed 45-57%.We have developed a more convenient (from the preparative viewpoint) procedure for the synthesis of bis(2-aminophenyl) ditelluride (Ia) and bis(2-amino-5-methylphenyl) ditelluride (Ib). As starting compounds we used readily accessible and hydrolytically stable N-trimethylsilyl-2-bromoanilines IIa and IIb. The reaction sequence shown in Scheme 1 is implemented as a one-pot process. The reaction of IIa and IIb with an equimolar amount of butylmagnesium bromide in THF gives N-bromomagnesio-N-trimethylsilyl-2-bromoanilines IIIa and IIIb which are converted into dimagnesium derivatives IVa and IVb by treatment with magnesium. Compounds IVa and IVb react with tellurium powder to afford bromomagnesium tellurolates Va and Vb, and hydrolysis of the latter involves removal of the trimethylsilyl protection and oxidation with atmospheric oxygen of intermediate tellurophenols to target ditellurides Ia and Ib. The yield of ditellurides Ia and Ib ranges from 65 to 67%.). Scheme 1. H 2 O, NH 4 Cl/[O] NH 2 Te R Ia, Ib Te NH 2 R NSiMe 3 Br R IIa, IIb BuMgBr -C 4 H 10 N Br R IIIa, IIIb BrMg SiMe 3 Mg N MgBr R IVa, IVb BrMg SiMe 3 Te N TeMgBr R Va, Vb BrMg SiMe 3
Organo-tellurium compounds S 0140 Synthesis of Bis(2amino-5-R-phenyl) Ditellurides. -[by a novel one-pot procedure using readily accessible and hydrolytically stable N-silylated 2-bromoanilines (I) as starting compounds]. -(ZAKHAROV, A. V.; AVANESYAN, K. V.; SADEKOV, I. D.; MINKIN, V. I.; Russ. J. Org. Chem. 41 (2005) 3, 467-468; Inst. Phys. Org. Chem., Rostov State Univ., Rostov-on-Don 344090, Russia; Eng.) -R. Staver 46-170
143ChemInform Abstract The reaction between the N-sulfonylseleniumimides (I) and the aromatic aldehydes (II) yields the N-sulfonylazomethines (III). The diphenylselenium oxide (IV), which is formed as a by-product, is known to react with sulfonamides, e.g. (V), the reaction resulting in the generation of (I). In the presence of catalytic amounts of (IV) the reaction between (II) and the sulfonamides (V) affords, as expected, (III) in fair yields.
ChemInform Abstract The oxidative power of chalcogen imides toward thiols and thioamides increases in the order S < Se < Te. This is due to the increasing polarity and, hence, decreasing stability of the chalcogen-nitrogen bond within this series. The aim of this investigation is to evaluate the influence exerted by electron-accepting or electron-donating substituents attached to the Se atom of selenium imides on the polarity of the Se-N bond. Diphenyl-and dibenzylselenium imides on reaction with the thiols (I) afford disulfides of type (II). The diphenylselenium imide and the dibenzylselenium imide differ in their behavior toward thiourea (Va), thiobenzamide (Vb) and N,N'-diphenylthiourea. The diphenyl derivative affords the 1,2,4-thiadiazoles (III) or (IV), whereas the dibenzyl derivative is found to be a stronger oxidant to give cyanamide (VIa), benzonitrile (VIb) or diphenylcarbodiimide (VII), thus demonstrating the enhanced Se-N polarity in the dibenzyl derivative.
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