Base-mediated [3 + 2]-cycloannulation strategy for the synthesis of pyrazolo[1,5-<i>a</i>]pyridine derivatives using (<i>E</i>)-β-iodovinyl sulfones
作者:Raju Jannapu Reddy、Nunavath Sharadha、Arram Haritha Kumari
DOI:10.1039/d2ob00499b
日期:——
with 1-aminopyridinium iodide is realized to access 2-substituted pyrazolo[1,5-a]pyridines in good to high yields. An essential modification of the dipolar N-tosylpyridinium imide allows the first preparative synthesis of 3-sulfonyl-pyrazolo[1,5-a]pyridines in moderate to high yields. Of note, the metal-free protocol features a broad substrate scope with good functional group tolerance and compatibility
吡唑并[1,5- a ]吡啶继续在药物化学中占据特殊地位,但3-磺酰基类似物的直接构建仍未探索。在碱性条件下,吡啶鎓-N-胺和相应的偶极胺在使用( E )-β-碘乙烯基砜的[3 + 2]-环加成反应中发挥了重要作用。K 2 CO 3介导的 ( E )-β-碘乙烯基砜与 1-氨基吡啶碘化物的串联环环脱磺酰基化反应以良好至高产率获得 2-取代的吡唑并[1,5- a ]吡啶。偶极N的基本修改-tosylpyridinium imide 首次以中等至高产率制备合成 3-磺酰基-吡唑并[1,5- a ] 吡啶。值得注意的是,无金属协议具有广泛的底物范围,具有良好的官能团耐受性和兼容性。通过克级反应证明了该过程的有效性,并根据具体结果提出了合理的机制。