Re‐Catalyzed Annulations of Weakly Coordinating N ‐Carbamoyl Indoles/Indolines with Alkynes via C−H/C−N Bond Cleavage

On Demand Synthesis of C3-N1' Bisindoles by a Formal Umpolung Strategy: First Total Synthesis of (±)-Rivularin A

In this work, a straightforward synthesis of C3-N1' bisindolines is achieved by a formal umpolung strategy. The protocols were tolerant of a wide variety of substituents on the indole and indoline ring. In addition, the C3-N1' bisindolines could be converted to C3-N1' indole-indolines and C3-N1'-bisindoles. Also, we have successfully synthesized (±)-rivularin A through a biomimetic late-stage tribromination as a key step.

Rhenium-catalysed reactions in chemical synthesis: selected case studies

This Perspective presents and discusses a selection of examples that reinforce the enabling and distinctive reactivity provided by homogeneous rhenium catalysis in chemical synthesis. Specifically, the ability for lower oxidation...

Facile Synthesis of Alkylidene Phthalides by Rhodium-Catalyzed Domino C-H Acylation/Annulation of Benzamides with Aliphatic Carboxylic Acids

The Rh-catalyzed ortho-C(sp² )-H functionalization of 8-aminoquinoline-derived benzamides with aliphatic acyl fluorides generated in situ from the corresponding acids has been developed. This reaction initiated with 8-aminoquinoline-directed ortho-C(sp² )-H acylation, which was accompanied by subsequent intramolecular nucleophilic acyl substitution of amide group to produce alkylidene phthalides This approach exhibits high stereo-selectivity for Z-isomer products, and tolerates a variety of functional groups as well as aliphatic carboxylic acids with diverse structural scaffolds.

Synthesis of Indole-Fused Oxepines via C-H Activation Initiated Diastereoselective [5 + 2] Annulation of Indoles with 1,6-Enynes

A rhodium-catalyzed diastereoselective formal [5 + 2] annulation of indoles with cyclohexadienone-containing 1,6-enynes has been established via indole 2,3-difunctionalization. The reaction, probably proceeding through tandem indole C2-H alkenylation and intramolecular Friedel-Crafts alkylation relay, provides rapid construction of indole-fused oxepines in good to excellent yields with a broad substrate scope. This method also features concomitant construction of cis-hydrobenzo[b] oxepine scaffolds, a core unit found in numerous natural products of important biological activities.

Redox-Neutral Rhodium(III)-Catalyzed Chemospecific and Regiospecific [4+1] Annulation between Indoles and Alkenes for the Synthesis of Functionalized Imidazo[1,5-a]indoles

Exploiting internal alkenes embedded with an oxidizing function/leaving group as a rare and unconventional one-carbon unit, a redox-neutral rhodium(III)-catalyzed chemo- and regiospecific [4+1] annulation between indoles and alkenes for the synthesis of functionalized imidazo[1,5-a]indoles has been achieved. Internal alkenes employed here can fulfill an unusual [4+1] annulation rather than normal [4+2] annulation/C-H alkenylation. This method is characterized by excellent chemo- and regioselectivity, broad substrate scope, good functional group tolerance, good to high yields, and redox-neutral conditions.

Rh(III)-Catalyzed Divergent Synthesis of Alkynylated Imidazo[1,5-a]indoles and α,α-Difluoromethylene Tetrasubstituted Alkenes

Herein, we report the divergent synthesis of alkynylated imidazo[1,5-a]indoles and α,α-difluoromethylene tetrasubstituted alkenes through Rh(III)-catalyzed [4 + 1] annulation/alkyne moiety migration and C-H alkenylation/DG migration, respectively. This protocol features tunable product selectivity, excellent chemo-, regio-, and stereoselectivity, broad substrate scope, moderate to high yields, good tolerance of functional groups, and mild redox-neutral conditions.

Cp*CoIII-Catalyzed C(7)-H Bond Annulation of Indolines with Alkynes

An efficient protocol for the synthesis of biologically essential pyrroloquinolinones has been developed under Cp*Co^III catalysis, which involves a cascade reaction of C(7)-H alkenylation with alkynes followed by nucleophilic addition. A wide variety of internal alkynes including enyne, diyne, and ynamide and more challenging terminal alkynes were successfully employed for the annulation in good to excellent yield with high regioselectivity.

Rhenium-Catalyzed Arylation-Acyl Cyclization between Enol Lactones and Organomagnesium Halides: Facile Synthesis of Indenones

A set of rhenium-catalyzed arylation-acyl cyclizations between (hetero)arylmagnesium halides and enol lactones through a cascade C(sp² )-C(sp² )/C(sp² )-C(sp² ) bond formation under mild reaction conditions has been developed. Indeed, a wide range of functional groups on both organomagnesium halides and enol lactones is well tolerated by the simple rhenium catalysis, thus furnishing polyfunctionalized indenones in one-pot fashion and with complete control of the regioselectivity. Moreover, this approach also provides a straightforward synthetic route to neolignan and (iso)pauciflorol F. Mechanistic studies demonstrated that the reaction involves a sequence of syn-carborhenation and intramolecular nucleophilic addition.

A Water-Soluble Rhenium(I) Catalyst for the Regio- and Stereoselective C(sp2)-H Alkenylation of N-Pyridyl-/N-Pyrimidylindole and the N-H Alkenylation of N-Pyrimidylaniline Derivatives with Ynamides

A water-soluble and low-valent rhenium(I) catalyst for the C2 alkenylation of N-pyridyl/N-pyrimidylindole derivatives with ynamides under mild conditions using water as the solvent has been described. The reaction of N-pyridyl/N-pyrimidyl indole with the ynamide afforded the C2-Z-selective alkenylation derivative as the sole product, and the reactions of N-pyrimidylanilines delivered the corresponding N-alkenylated product rather than the expected C-H alkenylation products in high yields under the same conditions.

Regioselective cascade annulation of indoles with alkynediones for construction of functionalized tetrahydrocarbazoles triggered by Cp*RhIII-catalyzed C–H activation

An efficient regioselective and stereoselective cascade annulation of indoles with alkynediones has been developed for construction of free (NH) tetrahydrocarbazoles with continuous quaternary carbons via Cp*Rh^III-catalyzed indole C2–H activation.

Rhenium-catalyzed alkylarylation of alkenes with PhI(O2CR)2via decarboxylation to access indolinones and dihydroquinolinones

Rhenium-catalyzed alkylarylation of alkenes with hypervalent iodine(iii) reagents (HIRs) via decarboxylation to access various 3,3-disubstituted indolinones and trans-3,4-dihydroquinolinones is described.