We thought this substitution reaction could offer a method for the construction of a diverse array of molecules containing the BCB motif. Optimization of the reaction between morpholine and the iodo-BCP 2b is described in Table . While the reaction tolerated different morpholine loadings (Entries 1-5), we found that the reaction was highly sensitive to solvent and reaction temperature. Deviating from 80 °C in DMSO led to decreased yields (Entries 6-9). Many solvents were inferior to DMSO (Entries 10-17). Hexafluoroisopropanol (HFIP) and 2,2,2trifluoroethanol (TFE), which are low-nucleophilic, carbocation-stabilizing solvents, decomposed the starting material and only provided trace yields of the product (Entries 10-11). In contrast, the reaction performed in NMP at 80 °C was sluggish, and the remainder of the mass balance was mostly leftover starting material (Entry 13). Table . Optimization of the iodo-BCP substitution reaction. a a Stock solutions of 2b and morpholine were combined in a 4 mL vial equipped with a magnetic stir bar. The vials were sealed and heated for 24 h and then a stock solution of 5,6-dibromobenzo[d][1,3]dioxole (0.1 M, CDCl3) was added as an internal standard. An aliquot was removed and then analyzed by 1 H NMR spectroscopy. b NMR yields. Isolated yields in parentheses. c 10 equiv. Ag2O added. d 10 equiv. ZnO added.