نتایج جستجو برای: stereoselectivity
تعداد نتایج: 1551 فیلتر نتایج به سال:
A facile alkenylation of quinazolines with unactivated terminal alkynes has been achieved in the presence of KOtBu without the aid of any transition metal catalysts. The reaction is carried out under very mild conditions and shows a high stereoselectivity. A possible radical-based mechanism is also explored.
Attractive carbocyclic structures are accessed via a highly regio- and enantioselective aminocatalytic γ-addition of cyclic enals to vinyl phosphonates followed by a one-pot intramolecular Horner-Wadsworth-Emmons reaction. It is also demonstrated that nitro olefins can act as electrophiles in a similar reaction concept, providing carbocycles in equally high stereoselectivity.
Methadone is administered as a racemate, although opioid activity resides in the R-enantiomer. Methadone disposition is stereoselective, with considerable unexplained variability in clearance and plasma R/S ratios. N-Demethylation of methadone in vitro is predominantly mediated by cytochrome P450 CYP3A4 and CYP2B6 and somewhat by CYP2C19. This investigation evaluated stereoselectivity, models, ...
This thesis describes the development of peptidic catalysts for stereoselective conjugate addition reactions of aldehydes and ketones to maleimides. In addition, mechanistic aspects of this conjugate addition were investigated and structural aspects of peptidic catalysts of the general H-DPro-Pro-type were studied. From a collection of tripeptides, H-DPro-Pro-Asn-NH2 was found to catalyze the c...
Reported herein is a photochemical cascade process that combines the excited-state and ground-state reactivity of chiral organocatalytic intermediates. This strategy directly converts racemic cyclopropanols and α,β-unsaturated aldehydes into stereochemically dense cyclopentanols with exquisite stereoselectivity. Mechanistic investigations have enabled elucidating the origin of the stereoconverg...
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