Synthesis of Trienes by Rhodium-Catalyzed Assembly and Disassembly of Non-Acceptor Cyclopropanes

The rhodium­(II)-catalyzed assembly of densely substituted cis-configured cyclopropyl ethers by decarbenation of cycloheptatrienes is reported. At higher temperature, these nonacceptor cyclopropanes open to give all-E trienes under the same catalytic system, in a one-pot procedure. Experimental and computational studies show that, for the formation of all-E trienes, the cyclopropanes undergo first a Rh­(II)-catalyzed cis- to trans-isomerization, followed by C–C bond cleavage.