Ruthenium-catalyzed cycloaddition of 1,6-diynes and nitriles under mild conditions: role of the coordinating group of nitriles.
In the presence of a catalytic amount of [Cp*RuCl(cod)] (Cp*=pentamethylcyclopentadienyl, cod=1,5-cyclooctadiene), 1,6-diynes were allowed to react chemo- and regioselectively with nitriles bearing a coordinating group, such as dicyanides or alpha-halonitriles, at ambient temperature to afford bicyclic pyridines. Careful screening of nitrile components revealed that a C[triple chemical bond]C triple bond or heteroatom substituents, such as methoxy and methylthio groups, proved to act as the coordinating groups, whereas C==C or C==O double bonds and amino groups failed to promote cycloaddition. This suggests that coordinating groups with multiple pi-bonds or lone pairs are essential for the nitrile components.
Yamamoto
Yoshihiko
Y
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan. yamamoto@apchem.nagoya-u.ac.jp
Kinpara
Keisuke
K
Ogawa
Ryuji
R
Nishiyama
Hisao
H
Itoh
Kenji
K
D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D009570:Nitriles / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D011725:Pyridines / Q000138:chemical synthesis*; D012428:Ruthenium / Q000737:chemistry
D000480:Alkynes; D009570:Nitriles; D009942:Organometallic Compounds; D011725:Pyridines; D012428:Ruthenium