- Microwave-assisted tandem cross metathesis intramolecular Aza-Michael reaction: An easy entry to cyclic β-amino carbonyl derivatives
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Hoveyda-Grubbs catalyst in combination with BF3·OEt2 efficiently promotes tandem cross metathesis intramolecular aza-Michael reaction between enones and unsaturated carbamates resulting in the creation of β-amino carbonyl units. The use of microwave irradiation dramatically accelerates the process, enhancing the synthetic utility of this methodology for the preparation of these types of derivatives. When enantiomerically enriched ∞-branched amines were used as starting materials, the process was also very efficient, although with modest selectivity in the newly created stereocenter. The use of microwave irradiation led to an interesting effect, inverting the selectivity in the addition process. Copyright
- Fustero, Santos,Jimenez, Diego,Sanchez-Rosello, Maria,Del Pozo, Carlos
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p. 6700 - 6701
(2008/02/04)
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- Room temperature palladium-catalyzed intramolecular hydroamination of unactivated alkenes
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A mild and facile Pd-catalyzed intramolecular hydroamination of unactivated alkenes is described. This reaction takes place at room temperature and is tolerant of synthetically useful acid-sensitive functional groups. The formation of hydroamination products rather than oxidative amination products is due to the use of a tridentate ligand on Pd which effectively inhibits β-hydride elimination. Copyright
- Michael, Forrest E.,Cochran, Brian M.
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p. 4246 - 4247
(2007/10/03)
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- The Cyclization of Hex-5-enylcarbamates and Related Compounds with Benzeneselenyl chloride and Some Reactions of the 2-Substituted Piperidine Products
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The reaction of hex-5-enylcarbamates with benzeneselenyl chloride gives adducts which cyclize in the presence of silica or stannic chloride, to 2-phenylselenomethylpiperidine derivatives which are unstable, both thermally and on silica.The selenoxides also undergo a Pummerer-type reaction to form 2-acetoxy(phenylseleno)methylpiperidine systems which can be oxidatively converted into a piperidine 2-aldehyde.The selenoxides react with carbon tetrachloride in base to form a 2,2,2-trichloroethyl substituent.Both the selenoxides and the phenylseleno groups of the cyclized products can be displaced by nucleophiles.Ethy hept-6-enylcarbamate did not give a cyclic product with benzeneselenyl chloride and silica, and gave a poor yield of a hexahydroazepine with stannic chloride.Hex-5-enamide cyclized to give a lactone, rather than a lactam, product.Hex-5-enenitrile gave Ritter reaction products with benzeneselenyl chloride in acetonitrile, and a dimer in non-nucleophilic solvents.
- Morella, Angelo M.,Ward, A. David
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p. 445 - 468
(2007/10/02)
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