Csp3-Csp3 and Csp3-H Bond Activation of 1,1-Disubstituted Cyclopentane

The unprecedented C-sp(3)-C-sp(3) bond cleavage of unactivated cyclopentane has been achieved. Rh-1-catalyzed cycloaddition of allenylcyclopentane-alkynes produced in situ the 9-cyclopentyl-8-rhodabicyclo[4.3.0]-nona-1,6-diene intermediates, which subsequently underwent [7+2] cycloaddition via beta-C elimination, affording bicyclo[7.4.0]tridecatriene derivatives in good yields. Changing the Rh-1 catalyst effected the C gamma-H bond activation of the common 9-cyclopenty1-8-rhodabicyclo[4.3.0]nona-1,6-diene intermediate to produce the novel spiro[2.4]heptane skeleton in a site-selective manner.