Selenation/Thionation of α-Amino Acids: Formation and X-ray Structures of Diselenopiperazine and Dithiopiperazine and Related Compounds
作者:Guoxiong Hua、Amy L. Fuller、Michael Bühl、Alexandra M. Z. Slawin、J. Derek Woollins
DOI:10.1002/ejoc.201100226
日期:2011.6
5-dithione and N-phenyl-2-(phenylamino)ethanethioamide. 2-Phenylglycine treated with an equivalent of Woollins' reagent under identical reaction conditions leads to only the formation of 2,5-diphenylpyrazine. Six X-ray structures are reported. DFT-B3LYP calculations suggest that the planar conformation is around 2 kcal/mol less stable than the puckered conformation for the bis-seleno derivative.
N-苯基甘氨酸与等量的 2,4-双-(苯基)-1,3-二硒二膦烷 2,4-二硒化物(伍林斯试剂,WR)反应生成主要产物 1,4-二苯基哌嗪-2,5 -diselenone 和作为次要产物 1,4-diphenyl-5-selenoxopiperazin-2-one。然而,使 N-苯基甘氨酸与等量的 2,4-双(4-甲氧基苯基)-1,3-二硫杂-2,4-二膦烷 2,4-二硫化物(劳森试剂,LR)反应得到 1,4-二苯基哌嗪- 2,5-二硫酮和 N-苯基-2-(苯基氨基)乙硫酰胺。在相同的反应条件下用等量的伍林斯试剂处理的 2-苯基甘氨酸仅导致形成 2,5-二苯基吡嗪。报告了六个 X 射线结构。DFT-B3LYP 计算表明,平面构象比双硒衍生物的褶皱构象稳定性低约 2 kcal/mol。