The argon laser-jet initiated, multiple-photon (reluctant), electrocyclic ring opening of 10,10-diphenyl-9-(10H)-phenanthrenone : A carbene and biradical modeling study
✍ Scribed by R.Marshall Wilson; Tatiana N. Romanova; Ardeshir Azadnia; Jeanette A. Krause Bauer; Richard P. Johnson
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- French
- Weight
- 306 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0040-4039
No coin nor oath required. For personal study only.
✦ Synopsis
While lO.lO-diphenyl-9-(lOIf]-phenantbrenone (1) is inert under conventional irradiatien conditions. it undergoes dembonyhtion under high-intensity argon laser-jet conditions to fum 9.9diphenylfluurene (3) and the cycluheptatriene 4. Mokcular modeling studies indicate tbat3 arim from collapse of the singlet c&ene IS and the ai-4 from tbe triplet carbcne 35.
Many potential photochemical reactions would seem to be highly favorable processes, and yet, are not observed. One such case involves the ketone 1 (Scheme 1). 1 The photochemical ring opening of 1 to the extended ketene methine 2 might be expected to be particularly facile via either a Norxish type I reaction or an electrocyclic ring opening. Contrary to expectations, low intensity irradiation of 1 (Rayonet Photochemical Reactor, 350 nm, 6 hours) led to virtually complete recovery of starting material. The inuiguing possibility existed that this type of reluctant reaction might be accessible from a higher excited state, and that the argon laser-jet technique2 might provide sufficiently high intensities to access these higher states through multiple-photon absorption. In fact, laser-jet irradiation of 1 (all UV lines 333.6-363.8 nm, 4 watts, 5 hours, benzene) does produce two new products: 9,9-diphenylfluorene