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Photodeconjugation, chiral induction

Buffer catalysis has been applied to induce chiral induction by enantio-selective protonation remarkable enantiomeric excess was achieved in the photodeconjugation of a,/3-unsaturated ketones and esters by using chiral catalysts for the ketonization of photoenols in aprotic solvents.29... [Pg.340]

While the concept of enantioselective photodeconjugation is of great interest, the process is efficient in relatively few cases and cannot be appHed to the total synthesis of natural products. The diastereoselective reaction has been also examined in parallel to the enantioselective one. High levels of induction (up to 88%) were first achieved using Hehnchen s derivatives as chiral alkoxy moieties (Scheme 20, entry a) " unfortunately, these chiral alcohols are expensive or require numerous steps to be prepared. [Pg.1443]

Because the synthesis of chiral fluoro compounds is of great interest, due to their biological properties, the asymmetric photodeconjugation of a-fluoro-a,P-unsaturated esters 46 has been explored. Despite the high acidity of the hydrogen on the C2 atom, the diastereoselective isomerization to the P.y-unsat-urated isomers is effective with levels of induction for 47 similar to those for non-fluorinated substrates (Scheme 25). [Pg.1446]


See other pages where Photodeconjugation, chiral induction is mentioned: [Pg.1442]    [Pg.219]    [Pg.322]    [Pg.219]    [Pg.322]    [Pg.99]    [Pg.93]    [Pg.94]   
See also in sourсe #XX -- [ Pg.120 ]




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