- Total synthesis of new indolo[2,3-a]quinolizine alkaloids sempervirine type, potential pharmaceuticals
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Total synthesis of the two series of new pentacycilc cycloalk[g]indolo[2,3-a]quinolizine alkaloids (modified sempervirine possessing the wide range of activity), has been elaborated in five steps from 5-acetyl-3-methylthio-1,2,4-triazine (obtained from the simple acyclic materials). In the two key steps: inverse electron demand Diels-Alder reaction of precursor with cyclic enamines and the following Fischer indolization of 3-acetyl-1-methylthiocycloalka[c]pyridines, the AB-DE synthons, has been obtained. The final stages: desulfuration, and formation of the C-ring via the Gribble method have led to the expected zwitterionic alkaloids. Model syntheses of the indolopyridocoline and its methoxy analogue from 2-acetylpyridine have been performed for investigation of the microwave-induced Fischer synthesis of sensitive indoles and for obtaining compounds for comparative study of spectroscopic data.
- Lipińska, Teodozja M.
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p. 5736 - 5747
(2007/10/03)
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- A DIRECTED METALATION ROUTE TO THE ZWITTERIONIC INDOLE ALKALOIDS. SYNTHESIS OF SEMPERVIRINE
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A synthesis protocol involving beta-lithiation of 2-(2-pyridinyl)indoles(45) and subsequent reaction with bromoacetaldehyde leads to the indoloquinolizine (1) ring system.Application of this methodology to 2-(2-pyridinyl)indole 17, which is prepared via Taylor-Boger triazine Diels-Alder annulation chemistry, affords the zwitterionic indole alkaloid sempervirine (3).
- Gribble, Gordon W.,Barden, Timothy C.,Johnson, David A.
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p. 3195 - 3202
(2007/10/02)
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