S-1 Supporting Information Tandem cycloaddition reactions of allenyl diazo compounds forming triquinanes via trimethylenemethane (TMM) diyls. Taek Kang, Won-Yeob Kim, Yeokwon Yoon, Byung Gyu Kim and Hee-Yoon Lee* Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon, 305-701, Korea Table of Contents Table of Contents S-1 General Information S-2 Synthetic Schemes for the Substrates S-4 Experimental Procedures Tandem reaction of linear substrate to linearly fused triquinane S-6 Tandem reaction of linear substrate to angularly fused triquinane S-10 Stereochemical assignment of the triquinanes by NOE experiment S-12 Appendix Spectral copies of the compounds S-13