Selective Ruthenium‐Catalyzed Alkylation of Indoles by Using Amines

Imm, Sebastian; Bähn, Sebastian; Tillack, Annegret; Mevius, Kathleen; Neubert, Lorenz; Beller, Matthias

doi:10.1002/chem.200903261

Cited by 64 publications

(25 citation statements)

References 70 publications

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“…A similar dehydrogenation of an amine (primary or secondary amine) to imine with catalyst 1 was used by Beller to alkylate indoles (9) [50]. The imine reacts with the indole to give an aminoalkylated intermediate, which undergoes elimination of ammonia or amine to give an oxidized indole intermediate.…”

Section: Oxidation Of Aminesmentioning

confidence: 99%

Shvo’s Catalyst in Hydrogen Transfer Reactions

Warner

Casey

Bäckvall

2011

Bifunctional Molecular Catalysis

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This chapter reviews the use of Shvo's catalyst in various hydrogen transfer reactions and also discusses the mechanism of the hydrogen transfer. The Shvo catalyst is very mild to use since no activation by base is required in the transfer hydrogenation of ketones or imines or in the transfer dehydrogenation of alcohols and amines. The Shvo catalyst has also been used as an efficient racemization catalyst for alcohols and amines. Many applications of the racemization reaction are found in the combination with enzymatic resolution leading to a dynamic kinetic resolution (DKR). In these dynamic resolutions, the yield based on the starting material can theoretically reach 100%. The mechanism of the hydrogen transfer from the Shvo catalyst to ketones (aldehydes) and imines as well as the dehydrogenation of alcohols and amines has been studied in detail over the past decade. It has been found that for ketones (aldehydes) and alcohols, there is a concerted transfer of the two hydrogens involved, whereas for typical amines and imines, there is a stepwise transfer of the two hydrogens. One important question is whether the substrate is coordinated to the metal or not in the hydrogen transfer step(s). The pathway involving coordination to activate the substrate is called the inner-sphere mechanism, whereas transfer of hydrogen without coordination is called the outer-sphere mechanism. These mechanistic proposals together with experimental and theoretical studies are discussed.

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Section: Oxidation Of Aminesmentioning

confidence: 99%

Shvo’s Catalyst in Hydrogen Transfer Reactions

Warner

Casey

Bäckvall

2011

Bifunctional Molecular Catalysis

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“…There are two examples of C‐3 alkylation of indoles by homogeneous transition‐metal catalysts 19. 20 Grigg and co‐workers demonstrated the first example with [Cp*IrCl 2 ] 2 catalyst and benzylic alcohols as alkylating reagents 19. Beller and co‐workers reported the Ru‐catalyzed system with benzylic and aliphatic amines 20.…”

Section: Alkylation Of Indole By 1‐octanol With 5 Wt % Metal‐loaded γmentioning

confidence: 99%

“…20 Grigg and co‐workers demonstrated the first example with [Cp*IrCl 2 ] 2 catalyst and benzylic alcohols as alkylating reagents 19. Beller and co‐workers reported the Ru‐catalyzed system with benzylic and aliphatic amines 20. Among these methods, the Grigg method is the most atom efficient way to form C‐3‐alkylated indoles, because water is the only byproduct.…”

Section: Alkylation Of Indole By 1‐octanol With 5 Wt % Metal‐loaded γmentioning

confidence: 99%

General and Selective C‐3 Alkylation of Indoles with Primary Alcohols by a Reusable Pt Nanocluster Catalyst

Siddiki

Kon

Shimizu

2013

Chemistry A European J

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“…In this respect, the conversion of secondary amines into primary ones is an attractive transformation. Although Williams and co-workers [13] and our group [14] have shown that secondary and even tertiary amines can be activated and used in the alkylation of aliphatic and aromatic amines, to the best of our knowledge no similar reactions with ammonia have been reported, yet.…”

mentioning

confidence: 89%

“…Based on the experience in amine-amine coupling reactions, [14] we chose the splitting of dicyclohexylamine as a model reaction for our investigations (Scheme 2). First, we examined different catalytic systems using 1 mmol dicyclohexylamine, 2 mol % of catalyst, 1 mL tert-amyl alcohol, and 1 g ammonia at 130 8C for 16 h. [17] Unfortunately, Milsteins catalyst (1) [12c] and our [Ru 3 (CO) 12 ]/cataCXiumPCy system (2), [18] both known to convert alcohols selectively into primary amines, gave no conversion (Scheme 3).…”

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confidence: 99%