Cp(*)RuCl-catalyzed formal intermolecular cyclotrimerization of three unsymmetrical alkynes through a boron temporary tether: regioselective four-component coupling synthesis of phthalides.
Highly substituted phthalides were efficiently synthesized by sequential Cp(*)RuCl-catalyzed cyclotrimerization of alkynylboronates, propargyl alcohols, and terminal alkynes and palladium(II)-catalyzed carbonylation of the resultant arylboronates. The intermediate arylboronate was isolated and unambiguously characterized by X-ray crystallography. The perfect regioselectivity of the ruthenium-catalyzed formal intermolecular cyclotrimerization was discussed on the basis of the density functional calculations of a boraruthenacycle intermediate.
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan. yamamoto@apchem.nagoya-u.ac.jp
Yoshihiko
Y
Yamamoto
Jun-Ichi
J
Ishii
Hisao
H
Nishiyama
Kenji
K
Itoh