A Highly Divergent Synthesis of 3‑Aminotetrahydropyridines

Dihapto-coordinate
1,2-dihydropyridine complexes of the metal fragment
{WTp­(NO)­(PMe3)} (Tp = tris­(pyrazolyl)­borate), derived from
pyridine, are demonstrated to undergo protonation at C6 followed by
regioselective amination at C5 with a variety of primary and secondary
amines. The addition takes place stereoselectively anti to the metal center, producing exclusively cis-disubstituted
products. The resulting 1,2,5,6-tetrahydropyridines can be successfully
liberated by oxidation, providing a route to novel molecules of potential
medicinal interest.

双齿配位（dihapto-coordinate）的金属片段{WTp(NO)(PMe3)}（Tp即三吡唑基硼酸根，tris(pyrazolyl)borate）的1,2-二氢吡啶配合物由吡啶衍生得到。研究表明，该配合物可先在C6位发生质子化，随后在C5位与多种伯、仲胺发生区域选择性胺化反应。该加成反应具有立体选择性，加成取向相对于金属中心为反式（anti），仅生成顺式二取代产物。所得1,2,5,6-四氢吡啶可通过氧化反应顺利释放，为制备具有潜在药用价值的新型分子提供了一条合成路径。