Eight-membered ring construction by [4 + 2 + 2] annulation involving beta-carbon elimination.
Cyclobutanones underwent a formal [4 + 2 + 2] annulation reaction with 1,6- and 1,7-diynes in the presence of nickel(0) catalysts to provide bicyclic eight-membered ring ketones. The annulation reaction proceeds through a ring-expansion of oxanickelacycloheptadiene via beta-carbon elimination to form a nine-membered nickelacycle. This reaction employing cyclobutanones as a C4 unit constructs cyclooctadienone cores in one synthetic step.
Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan. murakami@sbchem.kyoto-u.ac.jp
Masahiro
M
Murakami
Shinji
S
Ashida
Takanori
T
Matsuda