[reaction--see text] The antibiotic (-)-choramphenicol has been synthesized in only four steps from p-nitro-benzaldehyde in optically pure form from an asymmetric catalytic aziridination reaction with a chiral catalyst prepared from triphenylborate and the (R)-VAPOL ligand. Catalysts generated from the VAPOL and VANOL ligands give much higher asymmetric induction than do catalysts prepared from...

A catalytic asymmetric nitro-Mannich (aza-Henry) reaction with rare earth metal/alkali metal heterobimetallic catalysts is described. A Yb/K heterobimetallic catalyst assembled by an amide-based ligand promoted the asymmetric nitro-Mannich reaction to afford enantioenriched anti-b-nitroamines in up to 86% ee. Facile reduction of the nitro functionality allowed for efficient access to optically ...

A novel way to accommodate heterogeneous catalysis, CO2 fixation and asymmetric synthesis on one catalyst is reported. The [Co]@Ag composite was prepared for the first time and used for asymmetric carboxylation of benzyl bromides with CO2. All the procedures were performed under mild conditions. Moreover, the [Co]@Ag composite has terrific stability and reusability.

An asymmetric alkylation-ring-closing metathesis strategy was developed for the construction of a,a’-disubstituted medium ring ethers. The approach features an asymmetric alkylation of highly functionalized a-alkoxy acyl oxazolidinones followed by ring closure effected by Grubbs’ ruthenium catalyst. The relationship between diene conformation and the rate of ring-closure was examined.

Addition of a single functional handle to the tricyclic moiety of fluorescein results in asymmetric xanthene dyes. Our synthesis of a new class of asymmetric xanthenes proceeds via an unusual SNAr with sulfur nucleophiles on electron rich aromatic xanthenes scaffolds in the absence of a metal catalyst. The resulting 3'-thioethers exhibit high photostability and are conveniently converted into r...

Efficient catalytic asymmetric synthesis of 1,1-disubstituted tetrahydro-β-carbolines has been achieved via asymmetric alkylation of 1-cyanotetrahydro-β-carbolines using a binaphthyl-modified N-spiro-type chiral phase-transfer catalyst. This is a valuable example of hitherto difficult highly enantioselective alkylations at α-carbon of the cyano group under phase-transfer conditions.

Flava Flavanone: Asymmetric conjugate additions to chromones and 4-quinolones are reported utilizing a single catalyst system formed in situ from Pd(OCOCF(3))(2) and (S)-tBuPyOX. Notably, these reactions are performed in wet solvent under ambient atmosphere, and employ readily available arylboronic acids as the nucleophile, thus providing ready access to these asymmetric heterocycles (see scheme).

Abstract An asymmetric hydrogenation of enamines is efficiently catalysed by rhodium complexed with a fluorinated version the planar chiral paracyclophane-diphosphine ligand, Phanephos. This catalyst was shown to be very active, examples operating at just 0.1 mol% catalyst. then successfully adapted Direct Asymmetric Reductive Amination, leading formation several tertiary amines moderate ee, if...

Despite significant progress in the area of asymmetric hydrogenation, the enantioselective hydrogenation of aromatic and heteroaromatic compounds still remains a major challenge. Only a few examples with moderate enantioselectivity, which rely on unique catalyst systems and suffer from a limited scope of suitable substrates, have been described so far. There are several reasons that might expla...

The chelate ligands 1 -3 with lateral asymmetric centers at the nitrogen atoms were prepared and characterized. In the Rh complexes 4 and 5 the asymmetric centers directly interact with those coordination positions where during enantioselective catalysis prochiral substrates are converted into optically active products. The compounds 4 and 5, as well as the in situ catalysts [Rh(COD)Cl]2/2 were...