A flexible, stereoselective approach to the decorated cis-hydrindane skeleton: Synthesis of the proposed structure of faurinone
A flexible, stereoselective approach to the cis-hydrindane motif found in a number of biologically active natural products that utilizes highly diastereoselective SmI2-mediated cyclizations of aldehyde and halide substrates was demonstrated. Aldehydes were prepared to investigate the stereoselectivity of the proposed SmI2-mediated construction of the cis-hydrindane system. Treatment of aldehydes with SmI2 in THF and tBuOH resulted in successful cyclization and construction of three contiguous stereocenters. This cyclization proceeds through reduction of the aldehyde and addition of the resulting ketyl-radical anion to the alkene through anti-transition structure to give samarium (III) enolates. It was observed that SmI2-mediated halide-alkene cyclizations provide an easy alternative for the synthesis of less oxygenated targets.
Findley, Thomas J. K.,Sucunza, David,Miller, Laura C.,Davies, David T.,Procter, David J.
supporting information; experimental part
p. 6862 - 6865
(2009/07/18)
Sensitized Photooxygenation of Silyl Enol Ethers of Cyclic Ketones
α,β-Unsaturated and α-hydroxy ketones are accessible in prototropic ene-reactions with singlet oxygen by sensitized photooxygenation of cyclic silyl enol ethers and subsequent reduction and solvolysis.In a competing silatropic ene-reaction α-silyloxyketones are formed.Formation of different products depends on ring size, configuration and substitution.At C-6 chirally substituted 2-cyclohexenones are synthesized for the first time by sensitized photooxygenation of chiral silyl enol ethers of optically active starting ketones.
Friedrich, Edgar,Lutz, Werner
p. 1245 - 1263
(2007/10/02)
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