To optimize the reaction conditions, our endeavors started by reacting MBH ketone 1a and 2aminobenzothiazole (2a) as the model substrates for the reaction; the results obtained are illustrated in Table . Following the preliminary experiments that led to the discovery of this transformation (Table , entries1 and 2), a reaction was carried out at room temperature using Lewis acid catalyst In(OTf)3, which resulted in the formation of a trace amount of product 3a over a longer time period (entry 3). Reverting to the elevated reaction temperature and using the Lewis acid, we were pleased to find a good yield of the desired product (entry 4). Next, the screening of different solvents was carried out, which revealed that the reaction efficiency was reduced by employing lower boiling solvents in most cases (entries 5-9) and toluene proved to be the most effective solvent. Subsequently, various Lewis acid catalysts were tested (entries 10- ), and Ca(OTf)2 was found to be the most effective to produce an optimal yield of 3a. Finally, by examining the effect of catalyst loading on reaction efficiency, compatible results were obtained by lowering the catalyst loading to 5 mol% (entries 15 and 16). Hence, based on the above attempted efforts, the reaction of MBH ketone 1a with 1 equiv of 2a using 5 mol% Ca(OTf)2 in toluene at 110 C was found to be the optimal reaction conditions to further investigate the generality of the reaction (entry 16).