Rh(III)-Catalyzed Chemoselective [4 + 2] Annulations for the Synthesis of [1,3]Oxazinoindolones: A Combined Experimental and Computational Study.

The interaction of -alkoxy-1-indole-1-carboxamides with transition metals leads to indole-fused heterocyclic scaffolds through directing group leaving/migration, [3 + 2], N-C2 [4 + 1], and [4 + 2] annulations. However, the corresponding O-C2 [4 + 2] annulation reactions have never been reported. Herein, we report the chemoselective annulation of -alkoxy-1-indole-1-carboxamides catalyzed by Rh(III), affording [1,3]oxazinoindolones through a hitherto unknown reaction pathway.

Gold(I)-Catalyzed Regioselective Synthesis of Indenylidene Derivatives via 1,5-Acryl Migration.

A novel gold (I)-catalyzed synthetic strategy has been achieved for an efficient construction of indenylidene derivatives from substituted 1,6-diynes. This reaction describes the unique reactivity of gold catalysis in facilitating the intramolecular [3,3]-sigmatropic rearrangement, 5-exo dig cyclization followed by 1,5-migration of acryl group, resulting in the formation of substituted indenylidenes. Various substituted indenylidenes were successfully synthesized with up to 92 % yields.

Silver-catalyzed Regioselective Synthesis of N-aryl-1H-pyrazolyl-substituted Benzenesulfonamides from Ynamides and Pyrazoles.

Silver-catalyzed N-aryl-1H-pyrazolyl substituted benzenesulfonamide derivatives were obtained regioselectively from ynamides and pyrazoles. In this intermolecular organic transformation, several substituted benzenesulfonamides were obtained in good to excellent yields by forming a new C-N bond under mild reaction conditions.

Catalyst- and Additive-Free Methodical Ring Expansion Protocol to Access Benzooxepino-Fused Pyrroles.

An efficient metal-free, additive-free synthetic method was developed to access benzooxepino-fused pyrrole derivatives from alkynyl substituted aziridines. In this organic transformation, two new C-C bonds were formed via initial cleavage of C-C bond of aziridine ring by in situ generated azomethine ylides. Moderate to excellent yields of benzooxepino-fused pyrroles were obtained atom economically in the presence of t-BuOH in one-pot.

Gold(I)-Catalyzed Regioselective Cyclization to Access Cyclopropane-Fused Tetrahydrobenzochromenes.

Gold(I)-catalyzed efficient synthetic transformation was achieved to access the tetrahydrobenzo[]cyclopropa[]chromenes from allyl-substituted 1,6-diynes. Cyclopropane-fused tetrahydrobenzochromenes were obtained regioselectively in ≤92% yields. In this atom-economic organic transformation, three new C-C bonds were formed sequentially in one pot.

Cationic Gold-Catalyzed Intramolecular Cyclization of Substituted 1,5-Diynes to Access Indenone Derivatives.

An efficient intramolecular cyclization reaction was developed to achieve indenone derivatives. The substituted 1,5-diyenes were converted to the corresponding indenones via a gold-catalyzed organic transformation, and moderate to excellent yields of the title molecules were obtained via formation of two C=O and one C-C bonds under mild reaction conditions in one pot.

Gold-catalyzed synthesis of 1-isochromene-4-carbaldehydes oxidative cascade cyclization.

An efficient gold-catalyzed formation of indenylidene-derived 1H-isochromene-4-carbaldehydes from substituted 1,5,10-triyne-O-silanes was developed under mild reaction conditions. In this reaction, gold-catalyzed selective oxidation, 1,2-migration, nucleophilic addition and then 5-endo-dig cyclization took place regioselectively. The indenylidene-derived isochromene-4-carbaldehydes were synthesized in moderate to very good yields via the formation of new C-C and C-O bonds in one pot.

Gold(iii) promoted formation of dihydroquinazolinones: double X-H activation by gold.

An efficient 2-furyl gold-carbene promoted synthetic method was developed for the formation of dihydroquinazolinones from enynones by dual insertion of anthranilamides. In this organic transformation a new C-O and two C-N bond formations occurred and dihydroquinazolinones were obtained with a quaternary centre in moderate to very good yields in one-pot synthesis.

Gold-Catalyzed Synthesis of 6-Hydroxyindoles from Alkynylcyclohexadienones and Substituted Amines.

An efficient gold-catalyzed formation of 6-hydroxyindoles from substituted alkynylcyclohexadienones and amines have been developed. In this reaction two new C-N bonds were formed, and moderate to very good yields of the 6-hydroxyindole derivatives were obtained in one pot. This organic transformation tolerates a range of substituted alkynylcyclohexadienones and amines, which resulted in 6-hydroxyindole derivatives selectively.