نتایج جستجو برای: asymmetric transformation
تعداد نتایج: 285010 فیلتر نتایج به سال:
this thesis deals essentially (but not from all aspects) with the extension of the notion of semigroup compactification and the construction of a general theory of semitopological nonaffine (affine) transformation semigroup compactifications. it determines those compactification which are universal with respect to some algebric or topological properties. as an application of the theory, it is i...
The first asymmetric ring-expansion carbonylation of meso-epoxides to β-lactones is reported. Two structurally diverse chiral Cr(III) chloro complexes in conjunction with Co(2)(CO)(8) were shown to be competent catalytic systems for this transformation, displaying significant levels of asymmetric induction of up to 56% ee.
A new asymmetric total synthesis of a phenanthroindolizidine alkaloid (S)-tylophorine is reported, which features a catalytic asymmetric allylation of aldehydes and an unexpected one-pot DMAP promoted isocyanate formation and Lewis acid catalyzed intramolecular cyclization reaction. In addition, White's direct C-H oxidation catalyst system converting monosubstituted olefins to linear allylic ac...
The asymmetric anti-aldol addition of ketone-derived donors and aldehyde acceptors is described. Asymmetric induction is achieved through the use of chiral N-amino cyclic carbamate (ACC) auxiliaries. The transformation exhibits essentially perfect anti-diastereoselectivity and enantioselectivity, and has the unusual feature of proceeding via thermodynamic, rather than kinetic control.
Asymmetric catalysis in flow has been attracting much attention very recently because of the potential advantages over its batchwise counterpart, such as highthroughput screening and synthesis, easy automation with the integration of on-demand reaction analysis, little or no reaction workup, and potential long-term use of the catalysts in the case of heterogeneous catalysis. Homogeneous asymmet...
The search for new ligands in asymmetric catalysis is a field of continuing interest. To facilitate practical applications, new ligands should be easy to prepare from simple and easily available starting materials. In this context, the use of chiral nitrogen compounds bearing an organochalcogen moiety and their metal complexes have gained increased importance in the field of asymmetric catalysi...
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