Facile synthesis of 2-arylmethylindoles and 2-vinylic indoles through palladium-catalyzed heteroannulations of 2-(2-propynyl)aniline and 2-(2-propynyl)tosylanilide
作者:Bimolendu Das、Priyanka Kundu、Chinmay Chowdhury
DOI:10.1039/c3ob41961d
日期:——
A facile method for the general synthesis of 2-arylmethylindoles has been developed through the reaction of 2-(2-propynyl)aniline or 2-(2-propynyl)tosylanilide with aryl iodides in the presence of Pd(OAc)2, PPh3, and DBU. 2-(2-Propynyl)tosylanilide is found to be reactive also towards electron deficient alkenes in the presence of Pd(OAc)2 and sodium iodide under an oxygen atmosphere, providing easy access to 2-vinylic indoles which possess exclusive E-stereochemistry in the side chain double bond. Operational simplicity, compatibility of the various functional groups, and ease of product formation are the hallmarks of these methods. A mechanism has been proposed to explain the product formation.
Ruthenium-Catalyzed Cycloisomerization of Aromatic Homo- and Bis-Homopropargylic Amines/Amides: Formation of Indoles, Dihydroisoquinolines and Dihydroquinolines
作者:Alejandro Varela-Fernández、Jesús A. Varela、Carlos Saá
DOI:10.1002/adsc.201100095
日期:2011.8
Ruthenium-catalyzed cycloisomerizations of aromatic homo- and bis-homopropargylic amines/amides efficiently afford indoles, dihydroisoquinolines and dihydroquinolines. These processes were regioselective (5- and 6-endo cyclizations) on using key Ru vinylidene intermediates. The presence of an amine/ammonium base-acid pair increased the rate of cyclization and facilitated the catalytic turnover.
Abstract Indoles, dihydroisoquinolines, and dihydroquinolines were efficiently prepared by ruthenium-catalyzed heterocyclizations of aromatic homo- and bis-homopropargyl amines/amides in the presence of an amine/ammonium base-acid pair. These regioselective 5-endo and 6-endo cyclizations most probably occur by nucleophilic trapping of key ruthenium-vinylidene intermediates. Indoles, dihydroisoquinolines
Synergistic Gold and Iron Dual Catalysis: Preferred Radical Addition toward Vinyl–Gold Intermediate over Alkene
作者:Haihui Peng、Novruz G. Akhmedov、Yu-Feng Liang、Ning Jiao、Xiaodong Shi
DOI:10.1021/jacs.5b05415
日期:2015.7.22
A dual catalytic approach enlisting gold and iron, synergy is described. This method offers readily access to substituted heterocycle aldehydes via oxygen radical addition to vinyl-gold intermediates under Fe catalyst assistance. This system shows good functional group compatibility for the generation of substituted oxazole, indole, and benzofuran aldehydes. Mechanistic evidence greatly supports selective radical addition to an: activated vinyl-Au double bond over alkene. This unique discovery offers a new avenue with great potential to further extend the synthetic power and versatility of gold catalysis.