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• 536-74-3 phenylacetylene 
• 1942-30-9 4-(phenylethynyl)nitrobenzene 
• 615-43-0 2-iodophenylamine 
• 88284-48-4 2-(trimethylsilyl)phenyl trifluoromethanesulfonate 
• 52512-27-3 N-phenyl-C-mesitylnitrone 
• 98-95-3 nitrobenzene 
• 4250-81-1 1-phenyl-1-pentyne 
• 1082725-43-6 N-(4-nitrobenzylidene)aniline oxide 

Relevant academic research and scientific papers

Dissecting the Electronic Contribution to the Regioselectivity of the Larock Heteroannulation Reaction in the Oxidative Addition and Carbopalladation Steps

Substituted 2-iodoaniline derivatives were prepared and utilized as reactants, along with asymmetric diarylacetylenes, to synthesize a series of 6-substituted-2,3-diarylindole derivatives via the Larock heteroannulation reaction. Electron-donating substituents on the 2-iodoaniline derivatives retarded the reaction, while electron-withdrawing substituents provided a complete conversion to the indole products. In addition, the electronic properties of the substituted 2-iodoaniline reactants displayed no influence toward regioselectivity. On the contrary, the electronic effect from unsymmetrical diarylacetylenes significantly influenced the regiochemical outcome of the reaction. Density functional theory calculations of the oxidative addition and carbopalladation steps revealed the electronic influences of the substituted 2-iodoaniline derivatives toward the overall rate of the reaction. In contrast, the electronic properties of the asymmetric diarylacetylene remained the critical product-determining factor of regioselectivity.

Selective Synthesis of N-Unsubstituted and N-Arylindoles by the Reaction of Arynes with Azirines

The transition-metal-free and temperature-dependent highly selective reaction of arynes with 2H-azirines allowing the synthesis of either N-unsubstituted or N-arylindoles has been developed. At 60 °C, arynes generated from 2-(trimethylsilyl)aryl triflates smoothly insert into 2H-azirines to form 2,3-diarylindoles with high selectivity. Interestingly, when the reaction was performed at -10 °C, the selectivity was switched to the formation of 1,2,3-triarylindoles in good yields.

A synthetic 2,3-diarylindole induces cell death via apoptosis and autophagy in A549 lung cancer cells

A series of 2,3-diarylindoles were synthesized via the Larock heteroannulation, and evaluated for their anticancer activity against A549 lung cancer cells. The most potent compound, PCNT13 with IC50 = 5.17 μM, caused the induction of two modes of programmed cell death, apoptosis and autophagy.

Rhodium(III)-Catalyzed Redox-Neutral C-H Annulation of Arylnitrones and Alkynes for the Synthesis of Indole Derivatives

By using a nitrone as the oxidizing directing group, a mild, practical and efficient rhodium(III)-catalyzed C-H functionalization for the synthesis of indole derivatives has been developed. This reaction obviates the need for an external oxidant and shows good functional group tolerance. The employment of a sterically hindered Mes group on the carbon center of the nitrone is crucial to produce indoles in high yield.

Rhodium-Catalyzed C-H Annulation of Nitrones with Alkynes: A Regiospecific Route to Unsymmetrical 2,3-Diaryl-Substituted Indoles

The direct C-H annulation of anilines or related compounds with internal alkynes provides straightforward access to 2,3-disubstituted indole products. However, this transformation proceeds with poor regioselectivity in the synthesis of unsymmetrically 2,3-diaryl substituted indoles. Herein, we report the rhodium(III)-catalyzed C-H annulation of nitrones with symmetrical diaryl alkynes as an alternative method to prepare 2,3-diaryl-substituted N-unprotected indoles with two different aryl groups. One of the aryl substituents is derived from N?C-aryl ring of the nitrone and the other from the alkyne substrate, thus providing the indole products with exclusive regioselectivity.

Regioselectivity of Larock heteroannulation: A contribution from electronic properties of diarylacetylenes

A series of 2,3-diarylindoles were synthesized from 2-iodoaniline and unsymmetrical diarylacetylenes using the Larock heteroannulation. Diarylacetylenes bearing electron-withdrawing substituents lead to 2,3-diarylindoles with substituted phenyl moieties at the 2-position as major products, while those with electron-donating groups preferably yield indole products with substituted phenyl moieties at the 3-position. The regioisomeric product ratios exhibit a clear correlation with Hammett σp values. DFT calculations reveal the origin of this effect, displaying smaller activation energy barriers for those pathways leading to the major regioisomer.