Problems and exercisesHeterocycle synthesis: Paal-Knorr, Hantzsch and Fischer
Exercise 1
Propose Paal–Knorr syntheses of 1-benzyl-2,5-dimethylpyrrole and 2,5-diphenylfuran. Which 1,4-dicarbonyl compound do you need in each case?
Exercise 2
Which indole is formed in the Fischer synthesis with phenylhydrazine and butan-2-one in strong acid? And with phenylhydrazine and pyruvic acid? Say which bond is formed in the [3,3] rearrangement.