Gold/Chiral Amine Relay Catalysis Enables Asymmetric Synthesis of C2-Quaternary Indolin-3-ones.

A mild and effective strategy for the asymmetric synthesis of C2-quaternary indolin-3-ones from 2-alkynyl arylazides and ketones by gold/chiral amine relay catalysis is described. In this reaction, 2-alkynyl arylazides undergo gold-catalyzed cyclization, nucleophilic attack, and oxidation to form intermediate 2-phenyl-3H-indol-3-ones, followed by an l-proline-catalyzed asymmetric Mannich reaction with ketones, to afford corresponding products in satisfactory yields with excellent enantio- and diastereoselectivities.

Asymmetric Double Oxidative [3 + 2] Cycloaddition for the Synthesis of CF3-Containing Spiro[pyrrolidin-3,2'-oxindole].

An asymmetric double oxidative [3 + 2] cycloaddition is reported. Oxidation of 3-((2,2,2-trifluoroethyl)amino)indolin-2-ones and ß-aryl-substituted aldehydes simultaneously and subsequent asymmetric cycloaddition in the presence of the chiral amino catalyst generated highly functionalized chiral CF3-containing spiro[pyrrolidin-3,2'-oxindole] with four contiguous stereocenters stereoselectively, which is characterized by directly constructing two C-C bonds from four C(sp3)-H bonds. This new method features mild conditions, broad substrate scope, and excellent functional group compatibility.

Gold-Catalyzed Cascade Reaction of 2-Alkynyl Aryl Azides with Enecarbamates for Direct Synthesis of α-(3-Indolyl)ketones.

α-(3-Indolyl)ketones are essential building blocks for the generation of biologically active molecules. We described a new method for the direct assembly of α-(3-indolyl)ketones through the cascade reaction of 2-alkynyl aryl azides with enecarbamates, in which the in situ generated α-imino gold carbene intermediate was trapped by enecarbamate to achieve umpolung reactivity of indole at the 3-position.

Access to 3-Sulfonamidoquinolines by Gold-Catalyzed Cyclization of 1-(2'-Azidoaryl)propargylsulfonamides through 1,2-N Migration.

We describe a gold-catalyzed cyclization of 1-(2'-azidoaryl)propargylsulfonamides for the synthesis of 3-sulfonamidoquinolines, featuring a rare and highly selective 1,2-N migration. The key α-imino gold carbene intermediate is generated through an intramolecular nucleophilic attack of the azide group to the Au-activated triple bonds in a 6-endo-dig manner.

Construction of 1,3-Oxazolidines through a Three-Component [3+2] Cycloaddition of Tetrahydroisoquinolines, Aldehydes, and Ethyl Ketomalonate.

A chemoselective and diastereoselective synthesis of fused oxazolidines was achieved by a three-component cascade reaction of tetrahydroisoquinolines (THIQs), α,ß-unsaturated aldehydes, and diethyl 2-oxomalonate. Probably due to the reactivity difference between the aldehyde and the ketone, the reaction proceeded through the condensation of THIQs with α,ß-unsaturated aldehydes and 1,3-dipolar cycloaddition of the generated azomethine ylide intermediate with 2-oxomalonate. The key features are easily available starting materials, mild reaction conditions, broad substrate scope, and high chemo- and diastereoselectivity.

Gold-catalyzed cyclization of 1-(2'-azidoaryl) propynols: synthesis of polysubstituted 4-quinolones.

An unprecedented gold-catalyzed procedure for the synthesis of polysubstituted 4-quinolones from 1-(2'-azidoaryl) propynols is described. The reaction undergoes an intramolecular nucleophilic attack of the azide group to the Au-activated triple bonds in a 6-endo-dig manner and subsequent gold-assisted expulsion of N2 to furnish an α-imino gold carbene intermediate, which triggers a 1,2-carbon migration and finally is converted to 2,3-disubstituted 4-quinolone.

Poly[aqua-(µ(5)-2-oxido-4-sulfonato-benzoato)lanthanum(III)].

The title compound, [La(C(7)H(3)O(6)S)(H(2)O)](n), forms a three-dimensional framework in which the asymmetric unit contains one La(III) atom, one 5-sulfosalicylate (2-oxido-4-sulfonatobenzoate) ligand and one coordinated water mol-ecule. The La(III) atom is coordinated by nine O atoms from three carboxyl-ate, three sulfonate and two hydroxyl groups, and one water mol-ecule, forming a distorted trigonal-prismatic square-face tricapped geometry.