Unfortunately, in marked contrast to 26 (Scheme 6), stirring 34 with or without triethylamine in THF under anhydrous conditions, did not furnish the desired NInC 35. In view of the above, the action of 1 on 34 was then subjected to further LC-MS analysis: during the course of several days' reaction time with multiple attempts under a variety of conditions and extensive LC-MS monitoring, it was revealed that both triethylamine and even 1 itself -even though was only added in slight excess i.e. 1.2 equiv. with respect to 34 -were detrimental to formation of 35. To this end, the aforementioned reaction was repeated; however, this time in the presence of catalytic amount of a Lewis acid i.e. zinc chloride (Scheme 9). Gratifyingly, zinc chloride was able to catalyse the coupling of 1 to 34 to give ethyl ester protected NInC 35, though in moderate yields (Scheme 9) after flash column chromatography purification, but in relatively good purity i.e. >90%, as verified by H NMR (ESI S54 †). It did not come as a surprise, as always, to find out that the ester hydrolysis of 35 was not fruitful; however, hydrolysis of its parent ethyl ester 34 was smoothly accomplished in excellent yields i.e. ≥99% (ESI S42 †), and more importantly purity i.e. >98%, as evidenced by H NMR (ESI S55 †).