Castellote Isabel, Vaquero Juan J, Fernández-Gadea Javier, Alvarez-Builla Julio
Departamento de Química Orgánica, Universidad de Alcalá, 28871-Alcalá de Henares, Madrid, Spain.
J Org Chem. 2004 Dec 10;69(25):8668-75. doi: 10.1021/jo048898o.
The palladium-catalyzed Suzuki cross-coupling reaction of arylboronic acids and 6-bromo- and 6,8-dibromo-3,4-dihydropyrrolo[1,2-a]pyrazines afforded 6-substituted and 6,8-disubstituted 3,4-dihydropyrrolo[1,2-a]pyrazines in good yields. Stille and Negishi coupling reactions have been used to prepare 6-heteroaryl-substituted derivatives in moderate yields by employing heteroaryl halides and 6-metalated 3,4-dihydropyrrolo[1,2-a]pyrazines as reaction partners. A variety of cyclic secondary amines have also been incorporated at position C-6 of 6-bromo-1-phenyl-3,4-dihydropyrrolo[1,2-a]pyrazine in the presence of the palladium catalyst Pd(2)(dba)(3) in conjunction with BINAP as ligand. This amination reaction is one of the few reported examples of such a palladium-catalyzed transformation on a pyrrole ring, although the reaction could not be extended to less nucleophilic amines.
芳基硼酸与6-溴-3,4-二氢吡咯并[1,2-a]吡嗪以及6,8-二溴-3,4-二氢吡咯并[1,2-a]吡嗪的钯催化铃木交叉偶联反应，以良好的产率得到了6-取代和6,8-二取代的3,4-二氢吡咯并[1,2-a]吡嗪。通过使用杂芳基卤化物和6-金属化的3,4-二氢吡咯并[1,2-a]吡嗪作为反应伙伴，施蒂勒和根岸偶联反应已被用于以中等产率制备6-杂芳基取代的衍生物。在钯催化剂Pd₂(dba)₃与联萘二苯膦（BINAP）作为配体的存在下，各种环状仲胺也已被引入到6-溴-1-苯基-3,4-二氢吡咯并[1,2-a]吡嗪的C-6位。这种胺化反应是在吡咯环上这种钯催化转化的少数报道实例之一，尽管该反应不能扩展到亲核性较弱的胺。
