Q9(e). Aromaticity and methyl shifts of a dimethyldihydropyrene system
For the given reactant and product [structures given in the paper]: (i) identify the reactant and the product as aromatic, anti-aromatic or non-aromatic; (ii) assign the reason for the appearance of the methyl protons of the reactant and the product at −4.25 ppm and 2.1 ppm, respectively.
Model answer
The free solution for 2018 answers questions 1, 4, 5, 6, 7 and 10, the ones picked in its time plan. This part is not answered on the site yet. New answers are announced on Telegram.
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Coversring currentdimethyldihydropyreneannuleneproton NMR shielding
All parts of Question 9
- 9(a) Chlorotriphenylmethane with silver: the trityl radical5 marks
- 9(b) Product and stereochemistry of an acid-catalysed silyl reaction5 marks
- 9(c) Electrocyclic product by Woodward–Hoffmann rules5 marks
- 9(d) Synthetic sequence for a given transformation5 marks
- 9(e) Aromaticity and methyl shifts of a dimethyldihydropyrene system10 marks