3-(2-, 3- and 4-Pyridyl)-2-methoxythiophenes have been prepared in good yields through the Pd(0)-cat-alyzed coupling of the three isomeric bromopyridines with 3-trimethylstannyl-2-methoxythiophene. This compound was prepared through halogen-metal exchange of 3-bromo-2-methoxythiophene followed by stannylation. 3-Bromo-2-methoxythiophene was prepared by dibromination and α-debromination of 2-methoxythiophen. Most attempts to demethylate 2-methoxy-3-pyridylthiophenes using a large variety of reagents failed, probably due to the instability and high reactivity of the desired 3-pyridyl-2-hydroxythiophene systems. Only 2-methoxy-3-(3-pyridyl)thiophene reacted with boron tribromide to give 3-(3-pyridyl)-3-thiolene-2-one, which only was stable in ether solution at −20°. The attempted demethylation of 2-methoxy-3-(2-pyridyl)thiophene with trimethylsilane chloride/sodium iodide in refluxing acetonitrile led to a dimer. Demethylation of the 2-methoxy-3-pyridylthiophenes with dibenzyl diselenide and sodium borohydride gave 3-pyridylthiophan-2-ones.

中文翻译：

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吡啶取代的羟基噻吩。IV。3-和4-（2-，3-和4-吡啶基）-2-羟基噻吩的制备

通过三个异构体溴吡啶与3-三甲基锡烷基-2-甲氧基噻吩的Pd（0）-催化偶合，已经以高收率制备了3-（2-，3-和4-吡啶基）-2-甲氧基噻吩。该化合物是通过3-溴-2-甲氧基噻吩的卤素-金属交换，然后进行甲锡烷基化反应制得的。通过2-甲氧基噻吩的二溴化和α-脱溴制备3-溴-2-甲氧基噻吩。使用各种试剂对2-甲氧基-3-吡啶基噻吩进行脱甲基的大多数尝试均失败了，这可能是由于所需的3-吡啶基-2-羟基噻吩系统的不稳定性和高反应活性。只有2-甲氧基-3-（3-吡啶基）噻吩与三溴化硼反应生成3-（3-吡啶基）-3-噻吩-2-酮，其仅在-20℃的醚溶液中稳定。在回流的乙腈中尝试用三甲基硅烷氯化物/碘化钠使2-甲氧基-3-（2-吡啶基）噻吩脱甲基化导致了二聚体。用二苄基二硒化物和硼氢化钠对2-甲氧基-3-吡啶基噻吩进行脱甲基，得到3-吡啶基噻吩-2-酮。