Stereoselective reduction of some indoles with triethylsilane-trifluoroacetic acid

Lanzilotti, A. E.; Littell, Ruddy; Fanshawe, William J.; McKenzie, Thomas C.; Lovell, F. M.

doi:10.1021/jo00394a013

Cited by 73 publications

(29 citation statements)

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“…First, N-methoxycarbonyltryptamine (6d), readily and quantitatively available from 6c by a conventional method, was converted to 7d by reduction with triethylsilane 15) (Et 3 SiH) in CF 3 COOH (TFA) in 97% yield.…”

Section: )mentioning

confidence: 99%

The Chemistry of Indoles. CIII. Simple Syntheses of Serotonin, N-Methylserotonin, Bufotenine, 5-Methoxy-N-methyltryptamine, Bufobutanoic Acid, N-(Indol-3-yl)methyl-5-methoxy-N-methyltryptamine, and Lespedamine Based on 1-Hydroxyindole Chemistry.

Somei

Yamada

Kurauchi

et al. 2001

CHEMICAL & PHARMACEUTICAL BULLETIN

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Tryptamine alkaloids such as serotonin 2) (1a, Chart 1), Nmethylserotonin 3) (1b), bufotenine 4a,b) (1c), 5-methoxy-Nmethyltryptamine 5) (2a), and melatonin 6) (2b) have marked physiological effects in spite of their simple chemical structures. Members of the alkaloid family are still increasing, thus bufobutanoic acid 7) (3a) and N- (indol-3-yl)methyl-5-methoxy-N-methyltryptamine 8) (4, Chart 2) have recently been isolated from Ch'an Su and the roots of Antirhea lucida (Sw.) HOOK (Rubiaceae), respectively. Lespedamine 9) (5, Chart 4) is an alkaloid isolated from Lespedeza bicolor var. japonica NAKAI.From the viewpoint of developing novel biologically active substances, the tryptamine alkaloids seem to be attractive target compounds. Although synthetic methods for 1a-c [2][3][4] and 2a,b 6) have already been established, they require many steps starting from expensive indoles having an oxygen functional group at the 5-position. In the case of 5, the unique 1-methoxyindole structure required chemists to devise an ingenious synthesis.10) Generally speaking, the above syntheses are complex compared to the simple structures of the target compounds. How to prepare a simple target in a simple way is the most challenging ongoing subject in our group.We have proposed 1-hydroxyindole hypotheses, 11) which could unify the biogenesis of many indole alkaloids by assuming 1-hydroxytryptamines (or 1-hydroxytryptophans) as common intermediates. In order to verify these hypotheses, we have created synthetic methods for the previously unknown 1-hydroxytryptamines.12) We have also realized unprecedented nucleophilic substitution reactions in indole chemistry, 13) which had been predicted in the hypotheses. 11)These findings were successfully applied to two simple synthetic routes to melatonin 1) (2b), starting from 6b and 6d through 8b and 8d, respectively. The present paper is a full report of the previous communications 14) and describes further applications of the above findings to novel and simple syntheses of 1a-c, 2a, 3a, 4, and 5 from tryptamine (6c). An alternative synthesis of 5 through 1-methoxy-2-oxindole derivatives is also reported.Syntheses of 1a, 1b, and 1c Syntheses of 1a-c were achieved as follows. First, N-methoxycarbonyltryptamine (6d), readily and quantitatively available from 6c by a conventional method, was converted to 7d by reduction with triethylsilane 15) (Et 3 SiH) in CF 3 COOH (TFA) in 97% yield. 1)Next, our 1-hydroxyindole synthetic method, 12) employing 30% hydrogen peroxide (H 2 O 2 ) in the presence of sodium tungstate dihydrate (Na 2 WO 4 · 2H 2 O) as a catalyst, was applied to 7d to produce a 67% yield of 1-hydroxy-N-methoxycarbonyltryptamine 1) (8d), a potent inhibitor of blood platelet aggregation.16) However, an attempt to obtain 8a from 7a by the 1-hydroxyindole synthetic method was unsuccessful because of the unstable nature of 8a.The desired regioselective nucleophilic hydroxylation at the 5-position was realized by reacting 8d with 85% formic acid (HCOOH) at room temperature for 14 h to a...

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Section: )mentioning

confidence: 99%

The Chemistry of Indoles. CIII. Simple Syntheses of Serotonin, N-Methylserotonin, Bufotenine, 5-Methoxy-N-methyltryptamine, Bufobutanoic Acid, N-(Indol-3-yl)methyl-5-methoxy-N-methyltryptamine, and Lespedamine Based on 1-Hydroxyindole Chemistry.

Somei

Yamada

Kurauchi

et al. 2001

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…Therefore, removal of the acid-labile protective groups from the tetrapeptide 4 and nonapeptide 2 was performed using a mixture of TFA=water=triisopropylsilane (90=5=5, v=v=v) for 30 min, the latter being an effective scavenger [38]. It should be noted that trialkylsilanes may cause reduction of Trp residues [39], converting the side-chain indole to an indoline. Hence, the use of the more hindered triisopropylsilane was necessary [38].…”

Section: Stepwise Synthesis Of Fragmentsmentioning

confidence: 99%

Total synthesis of zervamicin IIB and its deuterium-labelled analogues

et al. 1997

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For the first time the total synthesis of the peptaibol zervamicin IIB is described. Synthesis of this peptaibol was achieved by the Fmoc/tert-butyl strategy in solution using a fragment condensation approach. Three fragments of zervamicin IIB were obtained by stepwise elongation with Fmoc amino acids using BOP as a coupling reagent. For the introduction of the highly sterically hindered alpha-aminoisobutyric acid residues BOP/DMAP activation was applied. The fmoc group was removed by reaction with 0.1 M NaOH in dioxane/methanol/water (30/9/1, v/v/v). Peptide fragments were coupled by means of a new coupling reagent, CF3-PyBOP. Using the strategy developed, zervamicin IIB and two analogues specifically deuterium-labelled at different positions of the glutamine-11 residue have been synthesized in 40% overall yield based on the isotopically labelled amino acid and with 98 +/- 2% of isotope enrichment. FAB mass spectroscopy, 600 MHz 1H-NMR spectroscopy and high-performance liquid chromatography provided convincing evidence that the synthetic products, zervamicin IIB and its deuterium-labelled analogues, fully correspond to the naturally occurring zervamicin IIB.

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“…Yet another promising method that makes it possible to realize the stereospecific reduction of tetrahydro-γ-carboline derivatives uses triethylsilane in trifluoroacetic acid [64,135].…”

Section: Synthesis Of Cis-derivativesmentioning

confidence: 99%

γ-Carbolines and their hydrogenated derivatives. 2.* Hydrogenated derivatives of γ-carbolines: methods of synthesis (review)

Alekseyev

Kurkin

Yurovskaya

2010

Chem Heterocycl Comp

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Stereoselective reduction of some indoles with triethylsilane-trifluoroacetic acid

Cited by 73 publications

References 1 publication

The Chemistry of Indoles. CIII. Simple Syntheses of Serotonin, N-Methylserotonin, Bufotenine, 5-Methoxy-N-methyltryptamine, Bufobutanoic Acid, N-(Indol-3-yl)methyl-5-methoxy-N-methyltryptamine, and Lespedamine Based on 1-Hydroxyindole Chemistry.

The Chemistry of Indoles. CIII. Simple Syntheses of Serotonin, N-Methylserotonin, Bufotenine, 5-Methoxy-N-methyltryptamine, Bufobutanoic Acid, N-(Indol-3-yl)methyl-5-methoxy-N-methyltryptamine, and Lespedamine Based on 1-Hydroxyindole Chemistry.

Total synthesis of zervamicin IIB and its deuterium-labelled analogues

γ-Carbolines and their hydrogenated derivatives. 2.* Hydrogenated derivatives of γ-carbolines: methods of synthesis (review)

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