A Facile, Mild And Efficient One-Pot Synthesis of 2-Substituted Indole Derivatives Catalyzed By Pd(PPh3)2Cl2 (original) (raw)
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Heterogeneous Palladium Catalysts Applied to the Synthesis of 2- and 2,3-Functionalised Indoles
Advanced Synthesis & Catalysis, 2006
Heterogeneous palladium catalysts ([Pd(NH 3) 4 ] 2 þ /NaY and [Pd]/SBA-15) were applied to the synthesis of 2-functionalised indoles, giving generally high conversions and selectivities (> 89% yield) using only 1 mol % [Pd]-catalyst under standard reaction conditions (polar solvent, 80 8C). For the synthesis of 2,3-functionalised indoles by crosscoupling arylation, the [Pd]/SBA-15 catalyst was found to be particularly interesting, producing the expected compound with ¼ 35% yield after 12 days of reaction, which is comparable to the homogeneous catalyst, Pd(OAc) 2 (¼ 48% yield). In the course of the study, the dual reactivity of the indole nucleus was demonstrated: aryl bromides gave clean C À C coupling while aryl iodides led to a clean C À N coupling.
ChemCatChem, 2017
Herein we report a new straight forward catalytic synthesis of 2,3-disubstituted indoles from -diketones 1 and Nsubstitutes anilines 2 by employing [Pd(tfa)2]/dppf (1/1.5) under reductive conditions and without an external oxidant. The tandem reaction involves ketoenamine and ketoamine as intermediates and final dehydration-annulation reaction to obtain the 2,3-disubstituted indole. New palladium-hydride species which catalyze the reaction could not be isolated but a Pd-H species were observed in the NMR, IR spectroscopy and mass spectrometry (FAB+) studies. This work presents a new regioselective route with a plausible mechanism, to synthesize 2,3-disubstituted indoles under reductive conditions [a]
Journal of Combinatorial Chemistry, 2009
anilines, obtained by the Pd/Cu catalyzed coupling of terminal acetylenes with N,N-dialkyl-o-iodoanilines. These 3-iodoindoles undergo palladium-catalyzed Sonogashira and Suzuki coupling reactions to yield 1,2,3-trisubstituted indoles. These reactions have been applied to parallel library synthesis utilizing commercially available terminal acetylenes and boronic acids. The aforementioned chemistry has also been carried out on a chlorinated Wang resin as a solid support, affording 1,2,3,5tetrasubstituted indoles after cleavage from the support. A diverse 42-member library of highly substituted indoles has been synthesized.
The Journal of Organic Chemistry, 2006
New functionalizations of indoles via palladium-catalyzed reaction of indoles and 2-acetoxymethyl-substituted electrondeficient alkenes are reported. It was found that for Nprotected indoles the reaction proceeded smoothly in the presence of 5 mol % of Pd(acac) 2 and 10 mol % of PPh 3 at 80°C in HOAc, while for N-unprotected indoles, the reaction was carried out by using 5 mol % of Pd(dba) 2 or 2.5 mol % of Pd 2 (dba) 3 ‚CHCl 3 with 10 mol % of 2,2′-bipyridine as the catalyst in toluene. This strategy allows the selective installation of electron-deficient olefin functionality at the 3-position of indoles, which might be difficult to obtain by other methods and can be further elaborated.
Tetrahedron Letters, 2011
Arylamines Palladium catalysis Chiral ligands a b s t r a c t A direct PdBr 2 (BINAP)-complex catalyzed method has been developed to produce 2,3-disubstituted indoles by the reaction of arylamines with a-diketones under reductive (H 2 ) conditions. The synthetic methodology involves a tandem reaction of three steps and all the organic intermediates were isolated and characterized, the reduction products in this sequence are chiral and present interesting enantiomeric excess. This report constitutes a new and different route to synthesize indoles and a plausible mechanism is also suggested.