Allene-(E)-ene-yne N-tosyl-tethered substrates 3 a–3 h were efficiently prepared and their rhodium-catalyzed [2+2+2] cycloaddition reactions were evaluated. The cycloadditions are chemoselective as only the proximal double bond of the allene reacted to afford exocyclic double bonds in the fused-tricyclic scaffolds. The stereoselectivity depended on the catalytic system used. Reactivity between allene, alkene, and alkyne was studied for the first time by density functional theory calculations. This mechanistic study determines the order in which the unsaturated groups take part in the catalytic cycle

Financial support fro m the Spanish Ministry of Educatio n and Science (MINECO) (Project No. CTQ2014-54306-P and CTQ2015-64436-P), the DIUE of the Generalitat de Catalunya (Project No.: 2014SGR931, pre-doctoral grant to D.C. and ICREA Academia 2014 prize to MS), and the FEDER fund (European Fund for Regional Development) for grant UNGI08-4E-801 is gratefully acknowledged