The 1 H NMR spectrum features a singlet integrating to two protons for the a methylene group at 4.78 ppm. The tricoordinate resonance for HB Me oCb2 in the 11 B NMR spectrum at 70.9 ppm is gone with only peaks in the tetracoordinate/cluster region, notably a diagnostic doublet for the borate at -17.8 ppm ( 1 JB-H = 90 Hz). The 13 C NMR spectrum revealed a singlet at 79.4 ppm assigned to C3 that is consistent to the methylene of the iminium species. Reactions in chloroform and toluene led to comparable yields but in both cases the reaction took longer time to complete (entries 9 and 10) while THF completely shut down reactivity (entry 11). Using the optimized conditions for 1, the reactivity of other indole substrates with HB Me oCb2 was investigated (Scheme 1). First, we examined substitution on nitrogen. Indoles bearing n-butyl and benzyl groups on the nitrogen worked efficiently to give borylated products 2 and 3 in 80% and 86% yields, respectively (Scheme 1a). A stronger electron-withdrawing tosyl (Ts) or a bulky triisopropylsilyl (TIPS) group failed to provide any reaction. Interestingly, the parent indole did not undergo C2borylation, instead dearomative N-borylation occurred to achieve 4 in 90% yield (Scheme 1b). The structure was confirmed by a single crystal X-ray diffraction study (Fig. ).