865367-01-7Relevant academic research and scientific papers
One catalyst for both enantiomers: Uncovering the inversion of enantioselectivity in cinchona-mediated desymmetrization of glutaric meso-anhydrides
Iv?i?, Trpimir,Novak, Jurica,Do?li?, Nada,Hamer?ak, Zdenko
, p. 8311 - 8317 (2012)
A puzzling inversion of enantioselectivity dependent on catalyst loading was observed during the quinine-mediated desymmetrization of glutaric meso-anhydrides. This study presents the improvement of the catalytic path by the inclusion of carboxylic acid additives up to synthetically useful levels. The novel protocol utilizing 0.1 equiv of alkaloid and xanthene-9-carboxylic acid at room temperature (rt) was found comparable to the protocol requiring 1.1 equiv of alkaloid at -30 °C. Thus, by altering the protocol the same catalyst produces the opposite enantiomer. This occurrence was rationalized by an extensive computational study of the interactions governing the molecular complexes formed by quinine, methanol, 3-methylglutaric anhydride, and the acetic acid. It was found that in a quinine catalyzed reaction the alcohol and the anhydride were directly hydrogen bonded to the catalyst. On the other hand, in the reaction with additive the acid intercalates between the alcohol and quinine. Due to this insertion the alcohol approaches the anhydride from the opposite face, in agreement with the observed inversion of enantioselectivity
Enzymatic desymmetrization of 3-arylglutaric acid anhydrides
Fryszkowska, Anna,Komar, Marta,Koszelewski, Dominik,Ostaszewski, Ryszard
, p. 2475 - 2485 (2007/10/03)
Optically active (R)- and (S)-3-arylglutaric acid monoesters 3 were synthesized in quantitative yields and good stereoselectivities by lipase-catalyzed desymmetrization of the corresponding 3-arylglutaric anhydrides 2 with alcohols. It was observed that the stereochemical outcome of the reaction was influenced by the substituents present on the aromatic ring. The influence of the enzyme, alcohol, and solvent was systematically examined. Absolute configurations of the monoesters 3 were assigned by chemical correlation to corresponding lactones 4.
