An Efficient and Scalable Synthesis of the Endothelin Antagonists UK-350,926 and UK-349,862 Using a Dynamic Resolution Process

Enantioselective Synthesis of Tertiary α,α-Diaryl Carbonyl Compounds Using Chiral N,N'-Dioxides under Umpolung Conditions

Brønsted acid-catalyzed addition of the chiral N,N'-dioxide into ynamides generated enolonium ions in situ which underwent enantioselective alkylation by indoles, pyrroles, and phenols, without racemization of the formed tertiary center. This external oxidant approach allows for the use of unmodified nucleophiles and does not leave trace groups from the oxidant, which significantly increases the synthetic efficiency and the product diversity. Furthermore, the byproduct of the N,N'-dioxide could be efficiently recycled into an optically pure form.

Friedel-Crafts alkylation with α-bromoarylacetates for the preparation of enantioenriched 2,2-diarylethanols

Highly enantioenriched 2,2-diarylethanols can be efficiently synthesized through the Friedel-Crafts alkylation of (hetero)arenes with configurationally labile α-bromoarylacetates. The substitution of highly diastereoenriched α-bromoarylacetates occurs in the presence of AgOTf, and the subsequent reduction affords diverse 2,2-diarylethanols with high yields and enantioselectivities up to 99 : 1 er. In addition, the application of this asymmetric synthetic methodology to the preparation of highly enantioenriched dihydrobenzofuran and indoline derivatives is demonstrated.

Brønsted Acid Catalyzed Oxygenative Bimolecular Friedel-Crafts-type Coupling of Ynamides

A non-metal approach for accessing α-oxo carbene surrogates for a C-C bond-forming bimolecular coupling between ynamides and nucleophilic arenes was developed. This acid-catalyzed coupling features mild temperature, which is critical for the required temporal chemoselectivity among nucleophiles. The scope of nucleophiles includes indoles, pyrroles, anilines, phenols and silyl enolethers. Furthermore, a direct test of S_N 2' mechanism has been provided by employing chiral N,N'-dioxides which also enlightens the nature of the intermediates in related metal-catalyzed processes.

Generation of gold carbenes in water: efficient intermolecular trapping of the α-oxo gold carbenoids by indoles and anilines

The efficient intermolecular reaction of gold carbene intermediates, generated via gold-catalyzed alkyne oxidation, with indoles and anilines has been realized in aqueous media.

(R)-1-Phenylethylamine as chiral auxiliary in the diastereoselective synthesis of tetrahydro-β-carboline derivatives

Modified sodium borohydrides were used in the reduction of the imine moiety in compounds containing the (R)-1-arylethylamine motif as a chiral auxiliary. Diastereomeric products were formed with moderate to good stereoselectivity and were effectively separated by column chromatography.Key words: asymmetric synthesis, indole alkaloids, hydrogen bond.