Iridium-Catalyzed C(sp3)?H Addition of Methyl Ethers across Intramolecular Carbon–Carbon Double Bonds Giving 2,3-Dihydrobenzofurans
Intramolecular addition of an O-methyl C(sp3)?H bond across a carbon-carbon double bond occurs in the iridium-catalyzed reaction of methyl 2-(propen-2-yl)phenyl ethers. The Ir/(S)-DTBM-SEGPHOS catalyst promotes the reaction efficiently in toluene at 110–135 °C to afford 3,3-dimethyl-2,3-dihydrobenzofurans. Enantioselective C(sp3)?H addition is achieved in the reaction of methyl 2-(1-siloxyethenyl)phenyl ethers, affording enantioenriched 3-hydroxy-2,3-dihydrobenzofuran derivatives with up to 96% ee. (Figure presented.).
The first and efficient total synthesis of (±)-dasyscyphin D was achieved in 9 steps with 22.6% overall yield. The key steps involved a PtCl 2-catalyzed pentannulation reaction and acid-catalyzed double Robinson annulations.
The present invention relates to the different roles inorganic ion receptors have in cellular and body processes. The present invention features: (1) molecules which can modulate one or more inorganic ion receptor activities, preferably the molecule can m
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(2008/06/13)
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