- Ring-closing metathesis of allylic O,O- and N,O-acetals
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A variety of allylic O,O- and N,O-acetals were synthesized using a mild palladium-catalyzed coupling of an alcohol or sulfonamide with an alkyl or aryl 1,2-propadienyl ether. The resulting linear acetals were used for the synthesis of unsaturated rings via ring-closing metathesis, in which the acetal carbon-a precursor for oxycarbenium or N-sulfonyliminium ions, respectively-served as a reactive center for further introduction of functional groups. The products-unsaturated oxygen and nitrogen heterocyclic scaffolds - offer multiple opportunities for derivatization as illustrated with the synthesis of substituted dihydropyrans, chromenes, enantiopure tetrahydropyridines and an enantiomerically pure quinolizidine amino acid.
- Kinderman, Sape S.,Doodeman, Robin,Van Beijma, Jetze W.,Russcher, Jaap C.,Tjen, Kim C. M. F.,Kooistra, T. Martijn,Mohaselzadeh, Homayun,Van Maarseveen, Jan H.,Hiemstra, Henk,Schoemaker, Hans E.,Rutjes, Floris P. J. T.
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p. 736 - 748
(2007/10/03)
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- A ring-closing metathesis-mediated route to novel enantiopure conformationally restricted cyclic amino acids
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A combination of palladium-catalysed N,O-acetal formation, ruthenium- catalysed ring-closing metathesis and N-sulfonyliminium ion-mediated C-C bond formation constitutes an efficient and versatile route to a set of enantiomerically pure 2,6-disubstituted unsaturated pipecolic acid derivatives.
- Tjen, Kim C. M. F.,Kinderman, Sape S.,Schoemaker, Hans E.,Hiemstra, Henk,Rutjes, Floris P. J. T.
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p. 699 - 700
(2007/10/03)
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