A New Five-Membered Ring Forming Process Based on Palladium(0)-Catalyzed Arylative Cyclization of Allenyl Enones
作者:Hirokazu Tsukamoto、Yoshinori Kondo
DOI:10.1021/ol800509z
日期:2008.7.3
A palladium(0)/monophosphine catalyst promotes a novel arylative cyclization reaction of C1-, C2-, and C3-tethered allenyl enones with arylboronic acids to produce five-membered ring containing products. The regioselectivity of the process, associated with aryl group introduction into the allene moiety, depends on the length of the tether. This finding suggests that the cyclization reaction does not proceed through a carbopalladation pathway but rather via a route involving palladacycle-forming or "anti-Wacker"-type oxidative addition to the Pd-0 catalyst.
Microwave-Assisted Palladium(0)-Catalyzed Alkylative Cyclization of Allenyl Aldehydes Leading to 3-Substituted 3-Cycloalken-1-ols
3-cyclohexenols and -cyclopentenol based on Pd0-catalyzed alkylative, arylative, alkenylative, alkynylative, and borative cyclization reaction of allene−carbonyl compounds. Microwave irradiation increases not only the reaction rate but also the product yield by suppressing formation of hydroarylation byproducts observed in the same catalytic system. Cyclization of optically active 1,3-disubstituted allene aldehyde