Solution photochemistry. XII. Novel tricyclic ring systems from the photolysis of diels-alder adducts
✍ Scribed by John R. Scheffer; James Trotter; Rudolf E. Gayler; Cedric A. Bear
- Publisher
- Elsevier Science
- Year
- 1973
- Tongue
- French
- Weight
- 211 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0040-4039
No coin nor oath required. For personal study only.
✦ Synopsis
The photolysis of Diels-Alder adducts of E-benzoquinone has proven to be a fruitful method for the synthesis of cage compounds (3) as well as sesquiterpene-like ring systems (4,5,6). In this paper we report additional novel ring systems accessible in this way.
Irradiation (a > 340 nm) of dilute benzene solutions of the duroquinone-2,3-dimethylbutadiene Diels-Alder adduct 1 cleanly gave rise to products 2_ and 3 (Scheme I) which could be isolated in 23% and 46% yield respectively by silica gel column chromatography (7). Scheme I 4 Ho / \ 0 4 4 0 5 3 7 6 2 0 \s , 6 10 2 2 Photoproduct 2, mp 101-102: showed the following spectral characteristics: uv max (?leOH) 251 (E 7400), 325 nm (E 58); ir (CC14) 2.69 (OH), 5.98 (C=O) u; nmr (CC14) T 4.62 (m, 1, vinyl), 7.79 (broad s, 1, OH, disappears with D20), 8.12-8.25 (m, 9, vinyl methyls), 8.43 (d, 1, J = 12.5 Hz, one of Cl0 methylenes), 8.92 (s, 3, methyl), 9.03 (d, 1, J = 12.5
HZ, one of Cl0 methylenes), 9.14 (s, 3, methyl), and 9.20 (s, 3, methyl). These data, while completely in accord with structure 2_, did not rule out structure 4 whose formation is also mechanistically reasonable. This point was settled by means of a direct method single crystal X-ray structure determination which showed formula 2 to be correct.