Pyrrolodiazines. 6. Palladium-catalyzed arylation, heteroarylation, and amination of 3,4-dihydropyrrolo[1,2-a]pyrazines.
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.
Castellote
Isabel
I
Departamento de Química Orgánica, Universidad de Alcalá, 28871-Alcalá de Henares, Madrid, Spain.
Vaquero
Juan J
JJ
Fernández-Gadea
Javier
J
Alvarez-Builla
Julio
J
D000478:Alkylation; D000586:Amination; D002384:Catalysis; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D011719:Pyrazines / Q000138:chemical synthesis* / Q000737:chemistry; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry
D011719:Pyrazines; D011758:Pyrroles; D010165:Palladium