Gold(I)-Catalyzed Hydroxy Group Assisted C(sp2)-H Alkylation of Enaminones with Diazo Compounds To Access 3-Alkyl Chromones.

A strategy for expedient synthesis of 3-substituted chromones from easily available o-hydroxyarylenaminones and diazo compounds has been developed. Carefully conducted experimental and computational studies led us to propose an uncommon mechanistic pathway involving the hydroxyl group assisted alkylation of enaminones with in situ generated gold carbenes.

Catalytic Enantioselective 1,3-Alkyl Shift in Alkyl Aryl Ethers: Efficient Synthesis of Optically Active 3,3'-Diaryloxindoles.

Reported is the first organocatalytic asymmetric 1,3-alkyl shift in alkyl aryl ethers for the synthesis of chiral 3,3'-diaryloxindoles using a chiral Brønsted acid catalyst. Preliminary results showed that each enantiomer of the 3,3'-diaryloxindole, and a racemic mixture, showed different antiproliferative activities against HeLa cell lines by using an MTT assay.

Au(i)/Ag(i) co-operative catalysis: interception of Ag-bound carbocations with α-gold(i) enals in the imino-alkyne cyclizations with N-allenamides.

A co-operative Au(i)/Ag(i) catalyst system has been developed to utilize N-allenamides as nucleophilic enal equivalents for the interceptive capturing of incipient carbocations generated through π-acid-triggered imino-alkyne cyclization. The salient features include the in situ generation of silver-bound carbocations (from iminoalkynes), α-gold(i) enals (from N-allenamides) and union of these two species to form indolizines with the regeneration of Au and Ag catalysts.

Robustness screen in enantioselective catalysis enabled generation of enantioenriched heterocyclic scaffolds in one pot.

Enantioselective catalysis has emerged as a powerful synthetic paradigm and has accelerated the development of new methods to make diverse chiral molecules. Generally, these reactions are very sensitive to the steric and electronic environment present in the catalyst as well as the substrates. With this scenario, the presence of an additional component in the reaction mixture is expected to add complexity in achieving the enantioselective variants. Herein, we report that various enantioenriched molecules could be obtained from multiple starting materials in one pot. The reaction of aminoaromatics A with alkynols B1, B2, B3…︁Bn with a Au(I)/chiral Brønsted acid catalyst afforded AB1*, AB2*, AB3*…ABn*; while, the reaction of alkynols B with aminoaromatics A1, A2, A3…An under the same reaction conditions gave A1B*, A2B*, A3B*…AnB*.