Selective Mono- to Perarylations of Tetrabromothiophene by a Cyclobutene-1,2-diylbisimidazolium Preligand
作者:Alireza Rahimi、Jan C. Namyslo、Martin H. H. Drafz、Julian Halm、Eike Hübner、Martin Nieger、Nicola Rautzenberg、Andreas Schmidt
DOI:10.1021/jo201317t
日期:2011.9.16
m)tetrafluoroborate is applied as preligand in palladium-catalyzed cross-coupling reactions starting from tetrabromothiophene for the synthesis of mono-, bi-, tri-, and tetraaryl-substituted thiophenes bearing up to four different aryl rings. A synthetic kit for preparations of nine different substitution patterns of arylated thiophenes is presented by application of only one single catalyst system
(环丁-1-烯-1,2-二基)双(1-甲基咪唑鎓)四氟硼酸酯作为预配体应用于钯催化的从四溴噻吩开始的交叉偶联反应中,以合成单,双,三和四芳基-取代的噻吩带有多达四个不同的芳基环。通过仅使用一个单一的催化剂体系就可以提供一种合成试剂盒,该试剂盒用于制备九种不同的芳基化噻吩取代模式。与DFT计算(预测三芳基-3-溴噻吩和四芳基噻吩在能量上较低的旋转势垒)一致,在相邻的芳基环之间未检测到NOE效应。因此,通过将三芳基-3-溴噻吩还原为2,3,5-三芳基噻吩,随后进行HMBC,HSQC和NOESY NMR测量,阐明了它们合成的区域选择性。此外,