C sp 3-H bond activation triggered by formation of metallacycles: rhodium(I)-catalyzed cyclopropanation/cyclization of allenynes.

Giving direction: An C sp 3-H bond activation directed by a rhodacycle intermediate has been found to occur in a Rh(I)-catalyzed reaction between an allene moiety having a tert-butyl substituent, and tethered alkynes. Cyclic compounds containing a cyclopropane ring were obtained in good to high yields (up to 92%).