Synthesis of Anthryl-Substituted Bithienylpyridines and their N-Methylpyridinium Salts
作者:Franz Effenberger、Jochen M. Endtner、Burkhard Miehlich、Jürgen S. R. Münter、Martin S. Vollmer
DOI:10.1055/s-2000-6410
日期:——
The synthesis of bithiophenes with anthracene and pyridine as terminal groups is described. 3- and 4-thienylpyridines 3, derived from thiopheneboronic acid 1 and the respective bromopyridines 2a, b, were coupled with 2-(9-anthryl)-5-iodothiophene 4 to give the isomeric (9-anthryl)bithienylpyridines 5a, b. In order to introduce a methylene spacer between the donor anthracene and bithiophene, 5-(2,2′-bithienyl)magnesium bromide 7 was reacted with 2 to yield the bithienylpyridines 9a, b. The reaction of 9 with 9-hydroxymethylanthracene 10 gave 3- and 4-(9-anthrylmethyl)bithienylpyridines 11a, b. The linkage of pyridine to bithiophene via a methylene spacer was reached by reacting lithiobithiophene with the isomeric pyridinecarbaldehydes 14a, b. Dehydroxylation of the resulting carbinols 15a, b with NaBH3CN/ZnI2, however, afforded the N-cyanoborane adducts 16a, b, which were transformed to the desired 3- and 4-(bithienylmethyl)pyridines 18a, b by heating either in EtOH or in 6 N HCl. Pyridines 5, 9, 11, and 18 were methylated with CF3SO3Me in CH2Cl2 or Et2O as solvent to yield the corresponding pyridinium triflates 6, 12, 13, and 19 in high purity.
描述了以蒽和吡啶为末端基团的联噻吩的合成。源自噻吩硼酸1和相应的溴吡啶2a、2b的3-和4-噻吩基吡啶3与2-(9-蒽基)-5-碘噻吩4偶联,得到异构的(9-蒽基)联噻吩吡啶5a、5b。为了在供电子蒽和联噻吩之间引入亚甲基间隔基,5-(2,2'-联噻吩)溴化镁7与2反应生成联噻吩吡啶9a、9b。9与9-羟甲基蒽反应得到3-和4-(9-蒽甲基)联噻吩吡啶11a、11b。通过与异构的吡啶甲醛14a、14b反应,通过亚甲基间隔基将吡啶连接到联噻吩上。然而,用NaBH3CN/ZnI2使生成的醇15a、15b去羟基化,得到了N-氰硼烷加合物16a、16b,通过在EtOH或6 N HCl中加热,将其转化为所需的3-和4-(联噻吩甲基)吡啶18a、18b。用CF3SO3Me在CH2Cl2或Et2O为溶剂中对吡啶5、9、11和18进行甲基化,得到高纯度的相应吡啶季盐6、12、13和19。