Page number 1) General considerations, experimental procedures S2-S26 2) References for known compounds S26-S28 General Considerations 2-Mesityltributylstannane, 1 o-tolyltributylstannane, 1 4-(tributylstannyl)nitrobenzene, 2 4-S2 tert-butylphenyltriflate, 3 bis(2-aminoethyl)(2-benzylaminoethyl)amine, 4 bis[2benzylamino)ethyl](2-aminoethyl)amine, 4 and tris[2-(benzylamino)ethyl]amine 5 were prepared following literature procedures. All other reagents were commercially availableand were used as re ceived unless otherwise noted. Cesium fluoride (Aldrich) was ground to fine powder and then dried under vacuum at 100 °C for 12 h prior to use. THF, 1,4dioxane, and pentane were distilled from Na/benzophenone under argon and degassed prior to use. Acetonitrile was distilled from CaH 2 under argon. Anhydrous DMF was purchased from Aldrich. For convenience, stock solutions of 1 and 2 in 1,4-dioxane (2 mM) were prepared and stored under argon. All reactions were performed under an atmosphere of argon in oven-dried glassware. 1 H and 13 C NMR spectra were recorded at 300 and 75 MHz, respectively, unless otherwise noted. The yields reported are isolated yields and are the average of two runs.