Abstract
Sensitised photolyses of ethoxycarbonyl oximes of aromatic and heteroaromatic ketones yielded iminyl radicals, which were characterised by EPR spectroscopy. Iminyls with suitably placed arene or heteroarene acceptors underwent cyclisations yielding phenanthridine-type products from ortho-additions. For benzofuran and benzothiophene acceptors, spiro-cyclisation predominated at low temperatures, but thermodynamic control ensured ortho-products, benzofuro-or benzothieno-isoquinolines, formed at higher temperatures. Estimates by steady-state kinetic EPR established that iminyl radical cyclisations onto aromatics took place about an order of magnitude more slowly than prototypical C-centred radicals. The cyclisation energetics were investigated by DFT computations, which gave insights into factors influencing the two cyclisation modes.
Original language | English |
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Pages (from-to) | 1083-1092 |
Number of pages | 10 |
Journal | Beilstein Journal of Organic Chemistry |
Volume | 9 |
DOIs | |
Publication status | Published - 4 Jun 2013 |
Externally published | Yes |
Bibliographical note
Copyright the Author(s) 2013. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.Keywords
- Cyclisation
- EPR spectroscopy
- Free radicals
- Heterocycles
- Oxime carbonates