With optimised conditions in hand, we evaluated them in the synthesis of a selection of challenging amides 1-24. We were particularly interested in examining the reactivity of medicinally relevant substrates such as polar heterocycles and poorly nucleophilic amines. Pleasingly, amides could be prepared effectively from heterocyclic carboxylic acids, containing a pyridine (1-2, 7), a quinoline (3), a tetrahydrofuran (4-5), and a thiophene (6). A range of anilines and related derivatives could also be employed including indoline (7), electron-rich anilines (8-10), electron-deficient anilines (11-13) and aminoheterocycles (14-15). Aliphatic amines including simple alkylamines (1-4), electron-deficient benzylamines ( ), secondary amines (5-6, 17), and branched systems (18, 22-24) were also good substrates. The amide 19 derived from 2-chloromandelic acid was obtained in only 38% yield, demonstrating the challenging nature of this particular substrate. Amides derived from hexanoic acid and dimethyldopamine (20) or 1-phenylethanolamine (21) were synthesised effectively, with the latter reaction demonstrating that the amidation reaction is chemoselective for acylation of the amine over the alcohol. Dipeptide synthesis from Boc-protected D-or L-alanine and Lphenylalanine tert-butyl ester proceeded efficiently, giving diastereomeric amides 22/23 with no observable epimerisation. Finally, the serotonin 5-HT3 receptor antagonist Granisetron 24 (used commonly as an antiemetic) could be prepared in 45% yield using only 20 mol% catalyst. Notably, in several cases amides were prepared from reactants where both the carboxylic acid and the amine can be considered as challenging substrates for catalytic amidation (5, 7, 13, 22-24). ‡ As can be seen in Scheme 2, with the exception of amide 20, tert-butyl acetate offers comparable or improved amide yields over amide syntheses previously performed in TAME or toluene. In most cases, the amides could be purified using a solid-phase work-up procedure employing scavenger resins to remove unreacted amine (Amberlyst 15), carboxylic acid (Amberlyst A-26) and boron compounds (Amberlite IRA743), with no requirement for aqueous work-up or chromatography. 3d