Ruthenium-catalyzed [2 + 2 + 2] cycloaddition of iododiynes

ORGN 436

Kozo Hattori, h051127m@mbox.nagoya-u.ac.jp and Yoshihiko Yamamoto, yamamoto@apchem.nagoya-u.ac.jp. Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya, 464-8603, Japan
Syntheses of polysubstituted iodobenzenes have often encountered difficulties associated with electrophilic aromatic substitution, for example, regioselectivity specific to pre-existent substituents and incompatibility to labile functionalities toward acidic and/or oxidative conditions. Here, highly substituted iodobenzenes were efficiently synthesized with defined substitution patterns from readily available diynes possessing iodinated alkyne terminals. The diiododiynes were capable of undergoing [2 + 2 + 2] cycloaddition with monoalkynes at room temperature in the presence of a catalytic amount of a ruthenium complex, Cp*RuCl(cod), resulting in the high yield formation of fused p-diiodobenzenes.