Several Lewis bases were screened for their nucleophilic capacity to catalyze the Staudinger cycloaddition of imine 1a with a para-nosyl group and phenylethyl ketene 2a (Scheme 1). Along with strong amine bases, alkali metal amides were also tested under different reaction conditions as shown in Table 1. Due to their nucleophilic nature, the best results were observed in the cases when amide catalysts were applied. Furthermore, the character of the alkali metal had an ...