Palladium-catalyzed direct heck arylation of dual pi-deficient/pi-excessive heteroaromatics. Synthesis of C-5 arylated imidazo[1,5-a]pyrazines.
A general and efficient synthesis of 5-aryl imidazo[1,5- a]pyrazines by palladium-catalyzed coupling of the corresponding 8-substituted derivatives with aryl halides is described. The scope of this new reaction for the imidazo[1,5- a]pyrazine ring system was explored using three readily available 8-substituted precursors, X = NH2, NMe2, and OMe, as well as 8-aryl derivatives, X = Ar'. On the basis of these results as well as studies using a deuterated derivative, a Heck-like mechanism is proposed for this transformation.
Wang
Jian-Xin
JX
Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
McCubbin
J Adam
JA
Jin
Meizhong
M
Laufer
Radoslaw S
RS
Mao
Yunyu
Y
Crew
Andrew P
AP
Mulvihill
Mark J
MJ
Snieckus
Victor
V
D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D006842:Hydrocarbons, Brominated / Q000737:chemistry*; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D011719:Pyrazines / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D006842:Hydrocarbons, Brominated; D007093:Imidazoles; D011719:Pyrazines; D010165:Palladium