Palladium(0)-catalyzed cis-selective alkylative and arylative cyclization of alkynyl enones with organoboron reagents

✍ Scribed by Hirokazu Tsukamoto; Takamichi Suzuki; Tomomi Uchiyama; Yoshinori Kondo

• Publisher: Elsevier Science
• Year: 2008
• Tongue: French
• Weight: 185 KB
• Volume: 49
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/j.tetlet.2008.04.111

✦ Synopsis

A palladium(0)-tricyclohexylphosphine catalyzes cis-selective alkylative and arylative cyclization of alkyne-containing electron-deficient alkenes with organoboron reagents to provide five-or six-membered rings with exo tri-or tetra-substituted alkenes. The opposite stereoselectivity to that for the alkyne-aldehyde cyclization using the same reagents would result from palladacycle-forming oxidative addition of the substrates to the Pd 0 catalyst followed by transmetalation with the boron reagents, protonation, and reductive elimination. The functional group compatibility, availability, stability, and nontoxicity of the reagents, and the fact that no additives are needed make the process more practical than the Ni 0 -catalyzed cyclization with organozinc reagents.