Many of the C2-and-C3 deuterated intermediates 2 have not previously been reported in the literature. If these compounds are desired, they can easily be isolated after the palladium-catalyzed deuteration step (Scheme 4). C3-Deuteration under these conditions was very high (75-95%) for all substrates, however purification by silica flash column chromatography was required which reduced the deuterium content at C3 to the values shown in Scheme 4 (e.g. from 70% to 46% for 2a). This effect was less pronounced for electron-poor indoles 3e, 3f and 3i. Deuteration of pindolol was achieved in 57% and 34% at C2 and C3, respectively. The use of anhydrous dioxane was of the utmost importance to avoid isotopic dilution at C3 (see ESI, Table ). As discussed above, when submitted to K2CO3 in MeOH/H2O, the isolated compounds 2 were cleanly transformed to the C2-deuterated compounds 6 shown in Scheme 3.