title: Regioselectivity of Larock heteroannulation: a contribution from electronic properties of diarylacetylenes.
abstract: 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 σ(p) values. DFT calculations reveal the origin of this effect, displaying smaller activation energy barriers for those pathways leading to the major regioisomer.
authors.affiliation: Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science and ‡Laboratory for Computational & Applied Chemistry (LCAC), Chemistry Department, Faculty of Science, Kasetsart University , Bangkok 10900, Thailand.
authors.forename: Nared
authors.initials: N
authors.lastname: Phetrak
authors.forename: Thanya
authors.initials: T
authors.lastname: Rukkijakan
authors.forename: Jakkapan
authors.initials: J
authors.lastname: Sirijaraensre
authors.forename: Samran
authors.initials: S
authors.lastname: Prabpai
authors.forename: Palangpon
authors.initials: P
authors.lastname: Kongsaeree
authors.forename: Chayada
authors.initials: C
authors.lastname: Klinchan
authors.forename: Pitak
authors.initials: P
authors.lastname: Chuawong
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D000814:Aniline Compounds / Q000737:chemistry; D004583:Electrons; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D013237:Stereoisomerism
chemical_list: C552400:2-iodobenzenamine; D000480:Alkynes; D000814:Aniline Compounds; D007211:Indoles