Novel total syntheses of (±)-oxerine by intramolecular Heck reaction
Both a three-step and a five-step syntheses of monoterpene alkaloid (±)-oxerine from alcohol 6 have been accomplished. In the second approach, the synthetic efficiency was enhanced by implementing a one-pot protocol (deprotonation/silylation/ alkylation/desilylation). The construction of the cyclopenta[c]pyridine framework was realized by an intramolecular Heck reaction, which should be adaptable for the synthesis of other related monoterpene pyridine alkaloids.
Pyridine radicals in synthesis. Part 3: Cyclopentannulation of pyridine via the 3-pyridyl radical and a formal synthesis of (±)-oxerine
The allylation and propargylation of 3-bromo-4-formylpyridine under zinc-mediated Barbier conditions is described. The homoallylic alcohols produced are cyclised via the derived 3-pyridyl radical to give cyclopentannulated pyridines. One of these bicyclic compounds is converted into an advanced intermediate in a previous synthesis of the monoterpene alkaloid (±)-oxerine. (C) 2000 Elsevier Science Ltd.
Jones, Keith,Fiumana, Andrea,Escudero-Hernandez, Maria L.
p. 397 - 406
(2007/10/03)
Pyridine radicals in synthesis: A formal total synthesis of (±)-oxerine
The cyclisation of pyridine radicals derived from 3-bromo-4-substituted pyridines carrying both alkene and alkyne groups in the 4-substituent to give is described. The cyclopentano[c]pyridine skeleton formed by cyclisation is found in many monoterpene alkaloids and a short synthesis of a late intermediate in the previous synthesis of (±)-oxerine is presented.
Jones, Keith,Fiumana, Andrea
p. 8049 - 8052
(2007/10/03)
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