The amine, 1, was chosen, as a stereoselective host/SPG (6-O-triisopropylsilylated β-cyclodextrin, "TIPS-β-CD", see Fig. ) for this amine is already established by Kida et al, achieving stereoselective recognition of the (S)-1 and kinetic resolution in more simple model reactions at low temperatures (-20 °C). Amberlyst 15, a polymeric resin with strongly acidic sulfonic acid groups, with was chosen as an available, affordable, achiral, and reusable solid acid catalyst. Exploring reaction conditions in the absence of TIPS-β-CD, in toluene (see SI, Table ; in the absence of protic solvents) we found that the imine (3a) formation reaction proceeds only in the presence of the Amberlyst 15 catalyst (Brønsted acid) at reduced temperatures (Table , Entries 4 & 5). Furthermore, the subsequent reduction of the imine (without isolation) to yield the amine (4a) product requires the catalyst, even at room temperature (Table , Entries 7 & 8): likely as the catalyst acts as a source of H + (4.7 mmol H + per g) for the initiation of the reduction in the presence of NaBH4 in an aprotic solvent. Taken together, in the low temperature conditions required for selective recognition of (S)-1 by TIPS-β-CD, the model reaction only proceeds when catalysed by Amberlyst 15.