Abstract:We describe here an efficient and regioselective synthesis of arylselanyl anilines by coppercatalyzed direct arylselenation of arylamines. Using a catalytic amount of copper iodide in dimethyl sulfoxide at 110 8C under an air atmosphere, a range of arylselanyl anilines was obtained directly from substituted diaryl diselenides in moderate to good yields via C À H bond cleavage of aryl amines.

We described herein our results on the silver-catalyzed synthesis of diaryl selenides via a cross-coupling reaction of diaryl diselenides with aryl boronic acids. The methodology is tolerant to electron-donor and electron-withdrawing groups at the substrates and the desired products were obtained in good to excellent yields.

We described herein the use of imidazolium ionic liquids [bmim]PF 6 and [bmim]BF 4 in the selective, metal and catalyst-free synthesis of unsymmetrical diaryl selenides by electrophilic substitution in arylboron reagents with arylselenium halides (Cl and Br) at room temperature. This is a general substitution reaction and it was performed with arylboronic acids or potassium aryltrifluoroborates bearing electron-withdrawing or electron-donating groups, affording the corresponding diaryl selenides in good to excellent yields. The ionic liquid [bmim] [PF 6 ] was easily recovered and utilized for further substitution reactions.

Bis-arylsulfenyl- and bis-arylselanyl-benzo-2,1,3-thiadiazoles were synthesized in good yields by copper-catalysed cross-coupling reaction of arylthiols or diaryl diselenides with the commercially available 4,7-dibromobenzo[c][1,2,5]thiadiazole.

Palavras-chave: adubo nitrogenado, ureia, eficiência do fertilizante, volatilização de amônia, N-(nbutil) triamida tiofosfórica. ABSTRACT Urea is the main nitrogen source used in flooded rice fields, but it is prone to ammonia volatilization losses. The use of N-(n-butyl) thiophosphoric triamide (NBPT) urease inhibitor, as urea additive, can reduce this inconvenient, inhibiting temporarily urea enzymatic degradation. An experiment was carried out on a Planossolo Háplico (Albaqualf), from October 2004 to April 2005, in Capão do Leão, RS, Brazil, to