Synthesis of Anionic Hypervalent Cyclic Selenenate Esters: Relevance to the Hypervalent Intermediates in Nucleophilic Substitution Reactions at the Selenium(II) Center
作者:Karuthapandi Selvakumar、Harkesh B. Singh、Nidhi Goel、Udai P. Singh、Ray J. Butcher
DOI:10.1002/chem.201003725
日期:2012.1.27
the two carboxylate groups via a hypercoordinate intermediate. The corresponding hypercoordinate intermediate (14 b, pyridinium selenuranide) for compound 14 was detected at low temperatures using 77Se NMR spectroscopy. The presumed hypercoordinate intermediates in the carboxylate‐exchange reactions at the selenium(II) center for a set of model reactions were optimized using DFT‐B3LYP/6–311+g(d) calculations
描述了包含2,6-二羧酸基团,2,2'-二硒烷基二基双(5-叔丁基间苯二甲酸)(10)的二芳基二硒烯的合成。Diselenide 10在甲醇中经历分子内环化反应,形成环状硒酸酯,即5-叔丁基-3-氧代-3 H -3苯并[ c ] [1,2]恶唑啉-7-羧酸(11)。在有机碱(例如吡啶,腺嘌呤和4,4'-联吡啶)存在下,环化反应进行得更快,形成吡啶鎓5-叔丁基-3-氧代-3 H-苯并[ c ] [1, 2]恶唑啉-7-羧酸盐(14),腺嘌呤5-叔丁基-3-氧代-3- ħ -苯并[ c ^ ] [1,2] oxaselenole -7-羧酸乙酯(15),和4,4'-二bipyridiniumbis(5-叔丁基-3-氧代-3 ħ -苯并[ c ] [1,2]-氧杂亚砜-7-羧酸盐)(16)。但是,2,2'-二硬脂基二基二苯甲酸(22)在相似条件下不会发生环化反应。上环selenenate酯结构研究14