- Electrophilic C12 building blocks for alkaloids: 1,1 iterative organoiron-mediated routes to (±)-lycoramine and (±)-maritidine
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Aryllithium reagents generated from protected 6-bromoguaiacol and 2-bromo-4,5-dimethoxybenzyl alcohol derivatives were used to prepare ortho-substituted (1-arylcyclohexadienyl)iron(1+) electrophiles. These were treated with Na+[Me3SiCH2CH2O 2CCHCN]- to build aryl-substituted quaternary centres in new examples of 1,1 iterative {[I·4] → [I·5]+ → [I·4] → [I·5]+ → [I· 4]} reaction sequences, which make use of the electrophilicity of the metal complex in two key carbon-carbon bond-formation steps. MOM protection of the guaiacol was better than SEM for access to the lycoramine skeleton, and TBDPS was best for maritidine. Decomplexation, hydrolysis, and cyclisation completed formal total syntheses of the Amaryllidaceae alkaloids (±)-lycoramine and (±)-marididine, establishing the compatibility of the organoiron method with the presence of ortho substituents on the aryl group, and nucleophile addition ipso to the substituted arene. Copyright
- Stephenson, G. Richard,Roe, Caroline,Sandoe, Elizabeth J.
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experimental part
p. 1664 - 1681
(2011/05/15)
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- Stereomanipulation of (η5-1-arylcyclohexadienyl)iron complexes
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A crystallographic investigation comparing five 1-aryl-substituted tricarbonyl[(1-5-η)-cyclohexadienyl]iron(1+) salts demonstrates that introducing additional electron density on the aromatic ring increases π overlap between the arene and the cyclohexadienyl ligand, thus flattening the structures sufficiently to make available a conformation in which nucleophiles can approach the site of substitution, despite the steric blockade of o-benzyl substituents. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Anson, Christopher E.,Malkov, Andrei V.,Roe, Caroline,Sandoe, Elizabeth J.,Stephenson, G. Richard
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p. 196 - 213
(2008/09/18)
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- Preparation of Novel 4-Substituted 6-Methoxy, 6,7-Dimethoxy-, and 6,7-(Methylenedioxy)isochroman-3-ones. 2
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The title compounds 20, 21, and 22 have been prepared in modest yields by a two-step reaction involving first the reaction of bromoarenes 3, 7, and 8 with lithioalkyl- and lithioarylacetonitriles under aryne-forming conditions.The cyano products 10, 14, and 16 so formed were then converted to the corresponding isochroman-3-ones by acidic hydrolysis.
- Khanapure, Subhash P.,Biehl, Edward R.
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p. 1471 - 1475
(2007/10/02)
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