1. Suggest a mechanistic pathway for formation of each of the products formed on irradiation of the Diels-Alder adduct of 2,3-dimethylbutadiene and quinone. 2. The direct irradiation of 20-A gives...

1. Suggest a mechanistic pathway for formation of each of the products formed on irradiation of the Diels-Alder adduct of 2,3-dimethylbutadiene and quinone.

2. The direct irradiation of 20-A gives predominantly 20-B, but the photosensitized reaction gives more 20-C. Explain these observations.

3. 9,10-Ethanoanthracenes undergo the di--methane rearrangement. Analyze the substituent effects that are observed in this reaction.