89188-93-2Relevant academic research and scientific papers
A palladium-catalyzed Barluenga cross-coupling – Reductive cyclization sequence to substituted indoles
Rahman, S. M. Ashikur,S?derberg, Bj?rn C. G.
, (2021/07/20)
A short and flexible synthesis of substituted indoles employing two palladium-catalyzed reactions, a Barluenga cross-coupling of p-tosylhydrazones with 2-nitroarylhalides followed by a palladium–catalyzed, carbon monoxide–mediated reductive cyclization has been developed. A one-pot, two-step methodology was further developed, eliminating isolation and purification of the cross-coupling product. This was accomplished by utilizing the initially added 0.025 equivalents of bis(triphenylphosphine)palladium dichloride, thus serving a dual role in the cross-coupling and the reductive cyclization. It was found that addition of 1,3-bis(diphenylphosphino)propane and carbon monoxide after completion of the Barluenga reaction afforded, in most cases, significantly better overall yields.
The regioselective Larock indole synthesis catalyzed by NHC-palladium complexes
He, Pan,Du, Yufeng,Liu, Gang,Cao, Changsheng,Shi, Yanhui,Zhang, Juan,Pang, Guangsheng
, p. 18345 - 18350 (2013/10/21)
The first practical and regioselective process for the synthesis of 2,3-disubstituted indoles from the reaction of o-iodoanilines or o-bromoanilines and their derivatives with symmetrical and unsymmetrical internal alkynes catalyzed by a ferrocene-functionalized N-heterocyclic carbene (NHC)-palladium complex has been developed, and the indoles were isolated in good yields with high regioselectivity.
Regioselective Pd-catalyzed indolization of 2-bromoanilines with internal alkynes using phosphine-free ligands
Cui, Xin,Li, Juan,Fu, Yao,Liu, Lei,Guo, Qing-Xiang
, p. 3458 - 3462 (2008/09/21)
The possibility of using phosphine-free ligands to promote Pd-catalyzed indolization of 2-bromoanilines with internal alkynes was examined for the first time. Phenylurea was found to be the optimal ligand, which could mediate the synthesis of 2,3-disubsti
Regioselective Indolization of Unsymmetrical Phenylhydrazones by Reaction, at Room Temperature, with PCl3
Baccolini, Graziano,Bartoli, Giuseppe,Marotta, Emanuela,Todesco, Paolo E.
, p. 2695 - 2697 (2007/10/02)
Unsymmetrical ketone phenylhydrazones (1) (R1 ae R2) react with PCl3, at room temperature to give predominantly one, (2), of the two possible 2,3-disubstituted indoles in good to excellent overall yield.When the R1 and R2 groups are very different (R1 = Ph or Me; R2 = alkyl or H) the reaction is highly regioselective leading to exclusive or prevalent formation of the corresponding 3-R1 indoles (2), whereas when R1 and R2 are very similar (R1, R2 = alkyl chains) the regioselectivity is decreased and the indole having the shorter chain in the 3-position predominates, but only slightly.Inspection of the results enables the direction of indolization to be predicted and the positions of the substituents in the 2,3-disubstituted indoles to be assigned with certainty, features not inherent in the classical Fischer indolization.
