Gannon Michael K, Detty Michael R
Department of Chemistry, University at Buffalo, The State University of New York, 627 Natural Sciences Complex, North Campus, Buffalo, New York 14260, USA.
J Org Chem. 2007 Mar 30;72(7):2647-50. doi: 10.1021/jo062370x. Epub 2007 Mar 3.
Deprotonation and lithium-bromine exchange in 5- or 3-bromothiophene-2-carboxylic acids with t-BuLi form the corresponding dianion, which reacts highly regioselectively in the presence of 0.25 equiv of tetramethyl-1,2-ethylenediamine with 3,6-bis(dimethylamino) chalcogenoxanthones to give S- and Se-containing rhodamines. Quenching studies with D2O indicate that an extra equivalent of t-BuLi is not necessary in these reactions. Deprotonation is faster than metal-halogen exchange with the bromothiophene-2-carboxylic acids using t-BuLi.
5-或3-溴噻吩-2-羧酸与叔丁基锂发生去质子化和锂-溴交换反应，形成相应的双负离子，该双负离子在0.25当量的四甲基-1,2-乙二胺存在下与3,6-双（二甲氨基）硫属黄原酮发生高度区域选择性反应，生成含硫和含硒的若丹明。用D2O进行的猝灭研究表明，在这些反应中不需要额外当量的叔丁基锂。使用叔丁基锂时，去质子化比与溴噻吩-2-羧酸进行的金属-卤素交换更快。
