Radical cyclisations to arenes for the synthesis of phenanthrenes
β Scribed by David C. Harrowven; Michael I.T. Nunn; David R. Fenwick
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- French
- Weight
- 57 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0040-4039
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π SIMILAR VOLUMES
The use of radical cyclisations allows direct access to a family of azaspiroeyclic ketones, including compounds having the azaspiro[4,4]nonane, and azaspiro[5S]undecane structures which are found in the alkaloids cephalotaxine and histrionicotoxin.
The Michael type addition of vinyl radicals on to the enone double bond was realised in Wieland-Miescher ketone derivatives leading to the formation of functionalised propellanes.
Radical cascade cyclisation of methylenecyclopropyl cyclohexanone adducts, using samarium diiodide to generate an initial ketyl radical, provide a short route to tricyclic ethers, and the stereochemical outcome can be influenced by the solvent used for the reaction.
An important reference has been unfortunately omitted : G. Stork & R. Mook Jr. (Tetrahedron Lett., 27, 4529 (1986)), recently reported such tin radical-mediated ethynyl cyclisations.