- Rhamnosylation: Diastereoselectivity of conformationally armed donors
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The α/β-selectivity of super-armed rhamnosyl donors have been investigated in glycosylation reactions. The solvent was found to have a minor influence, whereas temperature was crucial for the diastereoselectivity. At very low temperature, a modest β-selectivity could be obtained, and increasing temperature gave excellent α-selectivity. The donors were highly reactive, and activation was observed at temperatures as low as -107 °C. Different promoter systems and leaving groups were investigated, and only activation with a heterogeneous catalyst increased the amount of the β-anomer significantly. By introducing an electron-withdrawing nonparticipating group, benzyl sulfonyl, on 2-O, an increase in β-product was observed.
- Heuckendorff, Mads,Pedersen, Christian Marcus,Bols, Mikael
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scheme or table
p. 5559 - 5568
(2012/08/28)
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- Facile oxidative cleavage of 4-O-benzyl ethers with dichlorodicyanoquinone in rhamno- and mannopyranosides
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On exposure to dichlorodicyanoquinone in wet dichloromethane at room temperature, equatorial 4-O-benzyl ethers are removed with moderate selectivity in the presence of other benzyl ethers in glycopyranosides and glycothiopyranosides.
- Crich, David,Vinogradova, Olga
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p. 3581 - 3584
(2008/02/04)
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- Synthesis of a potent and selective inhibitor of p90 Rsk
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(Chemical Equation Presented) The synthesis of the naturally occurring kaempferol glycoside SL0101 has been accomplished, as has its biochemical evaluation. SL0101 exhibits selective and potent p90 Rsk inhibitory activity at nanomolar concentrations without inhibiting the function of upstream kinases such as MEK, Raf, or PKC. The synthesis verified the structural assignment of the natural product and has provided access to material sufficient for detailed biological evaluation.
- Maloney, David J.,Hecht, Sidney M.
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p. 1097 - 1099
(2007/10/03)
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