mechano

ya, right pritish. and C, i think would be :

hmmmmmmmm.... i thought bond would cleave out. anyway, good question.[1]

Dealing finishing touch to this thread -:

For those who never realized what happened in the last step here(including me),

The intramolecular acid base reaction is easier to occur than bond cleavage, so it's what happens.

Some might ask why C=N should degrade and C-O^- would reform to C=O. Suppose the acid base reaction took place and it was HO-C=N. Now tautomerization would occur anyway, and another intramolecular acid base reaction would transfer oxygen's proton to nitrogen.

Khaali time mein apani puraani posts hi dekhta rehta hai k...?
Smthing gud though, which i shud've done long back fr a bit of revision, but i nvr do :P