Palladium-catalyzed formation of 3,5-diaryl-1,2,4-selenadiazoles from arylselenocarboxamide

• Published in: Journal of organometallic chemistry 2002-08, Vol.656 (1), p.274-280
• Main Authors: Al-Rubaie, Ali Z., Yousif, Lina Z., Al-Hamad, Ali J.H.
• Format: Article
• Language: English
• Subjects: 3,5-Diaryl-1,2,4-selenadiazoles; Arylnitriles; Arylselenocarboxamides; Palladium(II) complexes
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/S0022-328X(02)01631-5

A number of new and known arylselenocarboxamides (i.e. Ar–C(Se)NH 2; Ar=C 6H 5 ( 1), 4-BrC 6H 4 ( 2), 2-MeOC 6H 4 ( 3), 4-MeOC 6H 4 ( 4), 4-MeSC 6H 4 ( 5), 4-EtOC 6H 4 ( 6), 2,3-(MeO) 2C 6H 3 ( 7), 3,4-(MeO) 2C 6H 3 ( 8), 3,5-(MeO) 2C 6H 3 ( 9), 4-PhC 6H 4 ( 10), 6-MeOC 10H 6 ( 11), 4-MeOC 10H 6 ( 12)) have been prepared in high yields by the reaction of arylnitrile with NaHSe. Treatment of arylselenocarboxamides (4 mmol) with aqueous Na 2PdCl 4 (1 mmol) in acetone at room temperature resulted in the formation of 3,5-diaryl-1,2,4-selenadiazoles as unexpected products together with palladium(II) complexes containing 3,5-diaryl-1,2,4-selenadiazoles. Treatment of arylselenocarboxamides (4 mmol) with catalytic amounts of Na 2PdCl 4 (10 −3 mmol) gave only 3,5-diaryl-1,2,4-selenadiazoles in good yields. 3,5-Diaryl-1,2,4-selenodiazoles were also prepared by oxidation of arylselenocarboxamides with iodine for comparison. Arylselenocarboxamides, Ar–C(Se)NH 2, were prepared in high yields by the reaction of arylnitrile with NaHSe. Treatment of arylselenocarboxamides (4 mmol) with aqueous Na 2PdCl 4 (1 mmol) in acetone resulted in the formation of 3,5-diaryl-1,2,4-selenodiazoles as unexpected products together with Pd-complexes containing 3,5-diaryl-1,2,4-selenodiazoles. Treatment of arylselenocarboxamides with catalytic amounts of Na 2PdCl 4 gave only 3,5-diaryl-1,2,4-selenadiazoles. 3,5-Diaryl-1,2,4-selenadiazoles were also prepared by the oxidation of arylselenocarboxamides with iodine for comparison.