Synthesis of oxa-aza spirobicycles by intramolecular hydrogen atom transfer promoted by N-radicals in carbohydrate systems
The nitrogen-centred radical generated by reaction of an N-phosphoramidate or N-cyanamide, attached to a tri- or tetramethylene tether extended from the C-1 of a carbohydrate, with (diacetoxyiodo)benzene (DIB) and iodine can undergo a regio- and stereoselective intramolecular hydrogen atom transfer (HAT) reaction to furnish four different oxa-azaspirobicyclic systems: 1-oxa-6-azaspiro[4.4]nonane, 1-oxa-6-azaspiro[4.5]decane, 6-oxa-1-azaspiro[4.5]decane and 1-oxa-7-azaspiro[5.5]undecane. A tandem 1,5- or 1,6-HAT-oxidation-nucleophilic cyclisation mechanism is proposed.
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| Main Authors: | , , |
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| Other Authors: | |
| Format: | artículo biblioteca |
| Published: |
Elsevier
2009-08-01
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| Subjects: | Intramolecular hydrogen atom transfer, N-Radical, Diacetoxyiodo, Benzene, N-Phosphoramidate, N-Cyanamide, |
| Online Access: | http://hdl.handle.net/10261/211686 http://dx.doi.org/10.13039/501100008737 http://dx.doi.org/10.13039/501100003339 |
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