In the light of what has been said above, there are no particular hard and fast rules for choosing the best Lewis acid/base catalyst for a given synthetic transformation, and what sometimes works best for one reaction, turns out to be completely futile for another, even for seemingly similar reactions as we saw above. As a result, ferric chloride in lieu of zinc chloride was able to catalyse the condensation of 36 with 1 so as to furnish the monumental NInC 37 in yields (Scheme 10) after flash column chromatography purification, acceptable purity, as evidenced by H NMR (ESI which otherwise, would have virtually impossible via any established PG strategy.