Tetrachlorocatecholborane was only moderately effective in this reaction. Notably, 2chlorophenylboronic acid performed as effectively as B(OAr F )3, giving a 73% yield of amide in 18 hours. a Determined using the Gutmann-Beckett acceptor method. Given the moderate reactivity improvements observed with this amidation reaction of unfunctionalized substrates and our desire to find catalysts for more difficult reactions, we then screened the catalysts against a more challenging amide formation reaction between 3fluorophenylacetic acid and 2-amino pyridine (Table ) both of which we have found to be relatively demanding substrates. Again, the reaction was stopped after 18 hrs to provide effective differentiation between catalysts; increased yields could be obtained if desired by running the reactions for longer. This reaction was much lower yielding, with all of the simple halogenated alkyl borate catalysts performing poorly (15-24% yield). Two results were notable -the boronic acid catalyst A in this case was completely inactive, in distinct contrast to the benzoic acid/benzylamine reaction above (Table ). Other catalysts containing boronic acids such as 2,4bis(trifluoromethyl)phenyl boronic acid E, where deleterious co-ordination of amines is reported to be hindered by the ortho substituent, and the BNO heterocyclic catalyst F (DATB2) were both low yielding. 3,4,5-trifluorophenyl borate B [B(OAr F )3] was demonstrably the most reactive catalyst for this amidation, and a moderate isolated yield of the amide (57%) could be obtained if the reaction time was extended to 66 hrs. With a new borate catalyst identified, we sought to explore its scope for the preparation of a range of challenging amides (Scheme 3). By switching the solvent to tert-butyl acetate Moderately hindered acids/amines could be used (e.g. 25, 27), but 1-adamantylamine showed low reactivity (26). Proline amides (28-29) could be prepared, although the when using a poorly reactive amine the yield was low (29). We then sought to further examine the limits of the new catalyst by screening the reaction of 2-amino pyridine with a range of carboxylic acids (4, 30-35). Primary alkyl carboxylic acids were coupled effectively (4, 30), more hindered N-Boc piperidine 4-carboxylic acid (31) and pivalic acid (32) reacted in good yield with prolonged reaction times. Aromatic carboxylic acids (33-35) proved less reactive, giving low yields even after prolonged reaction times, with the heterocyclic aromatic carboxylic acids (34-35) proving particularly challenging. To explore a more accessible procedure, we devised conditions for in situ formation of the catalyst via reaction of BH3.SMe2 and 3,4,5-trifluorophenol for direct use in an amidation reaction. This approach gave comparable or better yields for amides 4, 6, 10 and 12, and circumvents the need to prepare isolate the catalyst, enabling rapid evaluation of this novel catalytic system for challenging amidation substrates. Notably the in situ catalyst formation could be performed with only 2 eq of phenol with respect to BH3.SMe2.