Synthesis of .alpha.-monosubstituted indoles

Augustine, Robert L.; Gustavsen, A. J.; Wanat, S. F.; Pattison, I.; HOUGHTON, K. S.; Koletar, G.

doi:10.1021/jo00957a018

Cited by 61 publications

(20 citation statements)

References 4 publications

(5 reference statements)

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“…The physical constants and spectral data of azaindole 9 sample obtained by us correspond to literature values [9]. The conditions used in this work are probably not suitable for the preparation of azaindole derivatives.…”

supporting

confidence: 69%

“…Thus, compounds containing CN, CO 2 R, CO 2 H, COR, CONH 2 , and some other groups cannot be reduced using this method. 2-Nitro--nitrostyrenes 7a,b are reduced in moderate yield comparable to the yields obtained when using other reducing agents [9].…”

supporting

confidence: 57%

“…Only the bis-derivative 5 was formed when the reagent ratio was 1:3. Finally, we studied compounds, which were structurally similar to enamines 2, namely, 2-nitro--nitrostyrenes 7a,b, obtained by the condensation of substituted 2-nitrobenzaldehydes 6a,b with nitromethane [8] and nitroethane [9], respectively. The reduction and cyclization of all synthesized products was carried out under similar conditions.…”

mentioning

confidence: 99%

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Convenient modification of the Leimgruber-Batcho indole synthesis: reduction of 2-nitro-β-pyrrolidinostyrenes by the FeCl3–activated carbon–N2H4∙H2O system

Taydakov

Dutova

Сидоренко

et al. 2011

Chem Heterocycl Comp

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supporting

confidence: 69%

supporting

confidence: 57%

mentioning

confidence: 99%

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Convenient modification of the Leimgruber-Batcho indole synthesis: reduction of 2-nitro-β-pyrrolidinostyrenes by the FeCl3–activated carbon–N2H4∙H2O system

Taydakov

Dutova

Сидоренко

et al. 2011

Chem Heterocycl Comp

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“…The reductive cyclization of 2-nitrobenzyl ketones under dissolving metal conditions is well established as a route to the synthesis of indoles [1,2]. Earlier work from our laboratory studied a tandem reduction-Michael addition variant of this reaction as a route to the synthesis of 1,2,3,4-tetrahydroquinoline-2-acetic esters [3], and we have recently used this reaction to synthesize 1,2,3,9-tetrahydro-4H-carbazol-4-one [4].…”

Section: Introductionmentioning

confidence: 99%

Divergent reactivity in tandem reduction–Michael ring closures of five‐ and six‐membered cyclic enones

Bunce

Nammalwar

Slaughter

2009

Journal of Heterocyclic Chem

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in Wiley InterScience (www.interscience.wiley.com).In this study, methyl (AE)-1-(2-nitrobenzyl)-4-oxo-2-cyclohexene-1-carboxylate and methyl (AE)-(2-nitrobenzyl)-4-oxo-2-cyclopentene-1-carboxylate were prepared and subjected to reductive cyclization under dissolving metal conditions. The two reactants showed divergent behavior with the six-ring substrate reacting at the ester carbonyl and the five-ring substrate closing on the enone double bond. The difference in reactivity is attributed to the conformational flexibility, relative reactivity, and steric environment of C4-substituted six-and five-membered cyclic enones.

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“…1 H NMR data for known compounds were identical to those in the literature: 6a, 11e 6f, 11e 6e, 17 6g, 11e 6i, 18 6l, 19 6m, 5b 6o, 11e 6p, 20 and 6q. 21 The 13 C NMR, IR, and MS data are given below. All new compounds or those that have not been well-described in the literature were fully characterized on the basis of IR, 1 H NMR, 13 C NMR, and HRMS.…”

Section: Biomimetic Reduction Of Nitroalkenes; General Proceduresmentioning

confidence: 99%

Organocatalytic Biomimetic Reduction of Conjugated Nitroalkenes

Zhang¹,

Schreiner²

2007

Synthesis

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A thiourea-catalyzed biomimetic reduction of conjugated nitroalkenes has been developed. Various aromatic and aliphatic conjugated nitroalkenes can be reduced to give the respective nitroalkanes with good yields under mild conditions. This protocol is not only practical, but may also provide insight into the mechanisms of redox transformations in biological systems.Aliphatic nitroalkanes are valuable building blocks and intermediates in organic synthesis as well as in carbohydrate chemistry. 1 They are very useful tools for carboncarbon bond formation or carbon skeleton elongation because the high electron-withdrawing power of the nitro group stabilizes a-carbanions and enables their reactions with electrophiles under mild conditions. Moreover, the nitro group itself can be transformed into other functionalities such as, amongst others, carbonyl, amino, oxime, and hydrogen moieties. 2 The preparation and subsequent reduction of conjugated nitroalkenes has been widely accepted as a straightforward route to nitroalkanes, thus, there are quite a number of reducing reagents and reduction methodologies employed in this transformation. 3 Commonly used reductants include borohydride derivatives, metal hydrides, and metal halides. However, the selective reduction of the conjugated double bond is rather difficult because nitro-group reduction often takes place simultaneously. 4 Though sodium borohydride primarily furnishes the corresponding nitroalkanes, these reactions are often accompanied by the formation of polymeric side products through Michael addition of the nitronate intermediate to the starting nitroalkene. 5 Zinc borohydride is reported to be an efficient reagent with which to convert nitroalkenes smoothly into the corresponding nitroalkanes. 6 Metal-catalyzed hydrogenations and transfer hydrogenation are also very effective, however, due to the difficulties in handling or the toxicity of metal ions, new efficient and environmentally friendly methods remain desirable. 7In contrast to the chemical conversions described above, biological redox transformations using reduced nicotinamide adenine dinucleotide (NADH) as a coenzyme to reduce unsaturated functionalities, proceeds smoothly under very mild conditions. The ease with which such reactions takes place has been a stimulus for the development of a wide range of NADH models for a variety of reductions. 8 Among these, Hantzsch esters are one of the most widely investigated biomimetic reductants because they are inexpensive, stable and readily available. 9 Recent advances in organocatalysis have shown considerable promise for employing Hantzsch esters as the hydrogen source in asymmetric reductions as well as reductive aminations; 10 however, there is no organocatalytic method for the reduction of conjugated nitroalkenes. 11 Developments in biological and enzymatic catalysis have shown that isolated enzymes from baker's yeast or Old Yellow Enzyme (OYE), which was termed as nitroalkene reductase, can efficiently catalyze the NADPH-linked reduction of nitro-olefins...

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Synthesis of .alpha.-monosubstituted indoles

Cited by 61 publications

References 4 publications

Convenient modification of the Leimgruber-Batcho indole synthesis: reduction of 2-nitro-β-pyrrolidinostyrenes by the FeCl3–activated carbon–N2H4∙H2O system

Convenient modification of the Leimgruber-Batcho indole synthesis: reduction of 2-nitro-β-pyrrolidinostyrenes by the FeCl3–activated carbon–N2H4∙H2O system

Divergent reactivity in tandem reduction–Michael ring closures of five‐ and six‐membered cyclic enones

Organocatalytic Biomimetic Reduction of Conjugated Nitroalkenes

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