Intramolecular oxidative phenol coupling.  III.  Two-electron oxidation with thallium(III) trifluoroacetate

Schwartz, Martin A.; Rose, Bernard F.; Vishnuvajjala, Baburao

doi:10.1021/ja00783a064

Cited by 84 publications

(26 citation statements)

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“…Although hypervalent iodine(III) has been extensively used for intramolecular coupling reactions, 69,82 there has been little progress made in the intermolecular mode. 78a,83 Thallium(III) has also been successfully employed intramolecularly for the synthesis of isoquinoline alkaloids, 84 lignans 85 and colchinol derivatives 86 as well as aporphine alkaloids. 87 Effective oxidative dimerizations of 2-substituted indoles, 88 and indolocarbazoles 89 by thallium(III) trifluoroacetate have also been reported.…”

Section: Resultsmentioning

confidence: 99%

Stereospecific Approach to the Synthesis of Ring-A Oxygenated Sarpagine Indole Alkaloids. Total Synthesis of the Dimeric Indole Alkaloid P-(+)-Dispegatrine and Six Other Monomeric Indole Alkaloids

Edwankar

Namjoshi

et al. 2013

J. Org. Chem.

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The first regio- and stereocontrolled total synthesis of the bisphenolic, bisquaternary alkaloid (+)-dispegatrine (1) has been accomplished in an overall yield of 8.3% (12 reaction vessels) from 5-methoxy-D-tryptophan ethyl ester (17). A crucial late-stage thallium(III) mediated intermolecular oxidative dehydrodimerization was employed in the formation of the C9-C9′ biaryl axis in 1. The complete stereocontrol observed in this key biaryl coupling step is due to the asymmetric induction by the natural sarpagine configuration of the monomer lochnerine (6) and was confirmed by both the Suzuki and the oxidative dehydrodimerization model studies on the tetrahydro β-carboline (35). The axial chirality of the lochnerine dimer (40) and in turn dispegatrine (1) was established by X-ray crystallography and was determined to be P(S). Additionally, the first total synthesis of the monomeric indole alkaloids (+)-spegatrine (2), (+)-10-methoxyvellosimine (5), (+)-lochnerine (6), lochvinerine (7), (+)-sarpagine (8), and (+)-lochneram (11) were also achieved via the common pentacyclic intermediate 16.

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Section: Resultsmentioning

confidence: 99%

Stereospecific Approach to the Synthesis of Ring-A Oxygenated Sarpagine Indole Alkaloids. Total Synthesis of the Dimeric Indole Alkaloid P-(+)-Dispegatrine and Six Other Monomeric Indole Alkaloids

Edwankar

Namjoshi

et al. 2013

J. Org. Chem.

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“…[112][113][114][115][116][117][118] Many attempts to make spirodienones in vitro have been achieved by oxidative phenolic coupling reaction using heavy metal oxidizing reagents such as vanadium(V), iron(III), manganese(IV), or thallium(III) salts, but unsatisfactory results were encountered in many cases. [119][120][121][122][123][124][125][126][127][128][129][130][131] Alternatively, phenolic coupling reactions using hypervalent iodine(III) reagents could also lead to spirodienones from para-substituted phenols 79,82,[132][133][134][135][136] ; however, phenolic instability often causes difficulties in smooth conversions. Therefore the development of effective routes to spirodienones remains an important topic in organic synthesis.…”

Section: Oxidative Non-phenolic Coupling Reaction Leading To Biarylsmentioning

confidence: 99%

Development and Application of New Oxidation Systems Utilizing Oxometalate Catalysts

Hamamoto

2012

CHEMICAL & PHARMACEUTICAL BULLETIN

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This review describes our recent efforts in the development and application of new oxidation systems utilizing oxometalate catalysts. The novel use of heteropoly acid (HPA), an acidic oxometalate catalyst, in hypervalent iodine-mediated oxidations provided an effective strategy to generate cation radical species that enables a variety of direct C-H functionalizations of aromatic compounds. This strategy brought a facile biaryl synthesis and new spirodienone syntheses in aromatic oxidation chemistry. Moreover, this strategy opens up a facile synthetic route to morphinandienone alkaloids. On the other hand, the use of oxometalate catalyst together with poly(N-isopropylacrylamide) (PNIPAAm)-based polymer in the development of new solid-phase catalyst provided a novel reaction system in water. Due to the characteristic temperature-responsive intelligence of PNIPAAm, this reaction system brought a remarkable acceleration of the reactivity and ease of catalyst recovering in catalytic oxidation that uses hydrogen peroxide or oxygen gas (O 2 ) as primary oxidant. In addition, the recovered solid-phase catalyst could be used for consecutive reactions without any significant loss of its catalytic efficacy.

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“…In addition to the earlier methods, phenolic oxidations using dioxygen, halogens, enzymes, etc., also were reported sporadically. The introduction of vanadium complexes (VOCl 3 [15], VOF 3 [16]) and later of thallium [17] and lead reagents [18] offered more reliable reactions and partially solved problems such as over-oxidation and regioselectivity of CaC bond formation between aryl rings. With the use of these reagents, and also by electrochemical methods, it also became possible to utilize phenol ethers in coupling reactions.…”

Section: Introductionmentioning

confidence: 99%

Oxidative Aryl‐Coupling Reactions in Synthesis

Lessène

Feldman

2002

Modern Arene Chemistry

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The oxidant-mediated coupling of electron-rich arene rings has served over several decades as a valuable procedure to access biaryl units. The complex mixtures of isomers that often plagued the earliest studies have gradually given way to synthetically useful product distributions upon application of more selective coupling protocols. Continual advances in the nature of the oxidant (and its attendant ligands) and more precisely defined reaction conditions have led to increasing levels of control upon CaC bond formation. Chemoselective (CaC vs. CaO bond formation with phenols; suppression of product oxidation), regioselective (o-o 0 , vs. o-p 0 vs. p-p 0 CaC bond formation), and, more recently, stereoselective (atropisomer-selective) biaryl bond formation can now be achieved in many well-defined systems. A survey of the more recent advances in these areas is presented.14.1

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Intramolecular oxidative phenol coupling. III. Two-electron oxidation with thallium(III) trifluoroacetate

Cited by 84 publications

References 0 publications

Stereospecific Approach to the Synthesis of Ring-A Oxygenated Sarpagine Indole Alkaloids. Total Synthesis of the Dimeric Indole Alkaloid P-(+)-Dispegatrine and Six Other Monomeric Indole Alkaloids

Stereospecific Approach to the Synthesis of Ring-A Oxygenated Sarpagine Indole Alkaloids. Total Synthesis of the Dimeric Indole Alkaloid P-(+)-Dispegatrine and Six Other Monomeric Indole Alkaloids

Development and Application of New Oxidation Systems Utilizing Oxometalate Catalysts

Oxidative Aryl‐Coupling Reactions in Synthesis

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