Synthesis of 3,5-disubstituted pyridazines by regioselective [4+2] cycloadditions with ethynyltributyltin and subsequent replacement of the organotin substituent
作者:Jürgen Sauer、Dieter K. Heldmann
DOI:10.1016/s0040-4020(98)00127-6
日期:1998.4
Cycloadditions of 3-aryl-1,2,4,5-tetrazines 1a-o with ethynyltributyltin 5 occur with high regioselectivity to yield 3-aryl-5-tributylstannyl-pyridazines 9–23 in 71–95% yield. Moreover, the stannanes obtained could be utilized as starting materials for the preparation of various 3,5-di-substituted pyridazines as shown for 3-phenyl-5-tributylstannyl-pyridazine 9b. Stille cross-couplings with aryl halides
的3-芳基-1,2,4,5-四嗪环加成1A-O与ethynyltributyltin 5具有高的区域选择性发生,得到3-芳基-5-三丁基甲锡哒嗪9-23在71-95%的产率。此外,所获得的锡烷可以用作制备各种3,5-二取代的哒嗪的原料,如3-苯基-5-三丁基锡烷基-哒嗪9b所示。Stille与芳基卤化物的交叉偶联生成3,5-二芳基-哒嗪26-29,而暴露于元素卤素则提供了3-苯基-5-卤代哒嗪24和25,它们可以用作进一步官能化的起始化合物,例如Heck反应。