Answers to problems

This chapter presents the answers to the problems included in the previous chapters. Reaction of diketone with aminoketone produces enamine, which is not isolated, but cyclinizes directly to give pyrrole. Meanwhile, the application of generalised oxazole retrosynthesis leads to a simple glycine derivative. The mechanism of the oxazole formation is identical to that of the Hantzch thiazole synthesis. However, because of the reduced nucleophilicity of a carbonyl group as compared to a thiocarbonyl, this synthesis only proceeds under vigorous conditions. The alternative sequence would give a positional isomer oxazole. Finally, the overall electronic distribution of 2-pyrimidone has a considerable contribution from mesomer. The chapter also shows the mechanism of nitration.