Studies related to the chemistry of melanins. Part III. Synthesis of 5,6-dihydroxyindoline

Mishra, S. N.; Swan, G. A.

doi:10.1039/j39670001424

Cited by 6 publications

(8 citation statements)

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“…spectrum of this compound (i.e. 310 nm) was close to that previously reported for similar 5,6-dihydroxyindoline derivatives (10)(11)(12)(13)(14). The signals for the protons at positions 4-and 7-in the p.m.r.…”

supporting

confidence: 66%

Chemistry of Aminochromes. Part XV. The Reaction of Epinochrome with Thiols

Powell¹,

Heacock²

1972

Can. J. Chem.

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Epinochrome (5) has been shown to react with thioglycollic acid to give mainly 5,6-dihydroxy-I-methylindoline and a 4-thiosubstituted 5,6-dihydroxy-1-methylindoline. The acetyl derivatives of these compounds (i.r. 7b and 15), along with that of the corresponding 4-thiosubstituted 5.6-dihydroxyindole (i.e. l l ) , were isolated after acetylation of the reaction mixture. The latter compound is probably a secondary product of the reaction, having arisen from the 4-thiosubstituted 5,6-dihydroxy-1-methylindoline which is formed initially.On a montre que I'epinochrome (5) reagit avec I'acide thioglycolique pour conduire principalement au dihydroxy-5,6 methyl-1 indoline et au dihydroxy-5,6 methyl-l indoline thiosubstitue en position 4. Les derives acetyles de ces composes (c'est-a-dire 7b et 15) de m&me que ceux qui correspondent au dihydroxy-5,6 indole thiosubstitue en position 4 (par exemple 11) ont etC isoles a p r b acetylation du melange reactionnel. Le dernier compose est probablement un produit secondaire de la reaction provenant du dihydroxy-5.6 methyl-1 indoline thiosubstitue en position 4 qui s'est initialement forme.

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supporting

confidence: 66%

Chemistry of Aminochromes. Part XV. The Reaction of Epinochrome with Thiols

Powell¹,

Heacock²

1972

Can. J. Chem.

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“…The filtrate was concentrated to give a crude product, which was purified by crystallization from an appropriate solvent or by preparative TLC on silica gel, unless otherwise noted. The spectral data for the products 2a ,43,49–53 2b ,50,54 2c ,41,55 2d ,56 2f ,43,52 2g ,57,58 and 2h 3d,48–52 were compared with those reported.…”

Section: Methodsmentioning

confidence: 99%

“…N ‐Acetyl‐5,6‐dimethoxyindoline (2f): 43,52 Colorless crystals (95 %) from If‐I ; m.p. 170–172 °C (MeOH, ref 43.…”

Section: Methodsmentioning

confidence: 99%

Phosphane‐Free Pd⁰‐Catalyzed Cycloamination and Carbonylation with Pd(OAc)₂ and Cu(OAc)₂ in the Presence of K₂CO₃: Preparation of Benzocyclic Amines and Benzolactams

Harada¹,

Nishida²,

Uchiito³

et al. 2011

Eur J Org Chem

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Phosphane-free Pd 0 -catalyzed intramolecular aromatic amination was studied. o-Halophenethylamines and 3-(o-halophenyl)propylamines were found to be transformed into indolines and quinolines in a catalytic system based on Pd(OAc) 2 and Cu(OAc) 2 in the presence of K 2 CO 3 . Application of the method to substrates containing isoquinoline rings -the 1-(o-bromobenzyl)-3,4-dihydroisoquinolines 6, the 1-(o-bromobenzyl)-1,2,3,4-tetrahydroisoquinolines 7, and the 1-(o-bromophenethyl)isoquinolines 9 -provided the indolo[2,1-a]isoquinoline and dibenzo[a,f]quinolizine ring

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“…Da die grosse Reaktionsbereitschaft eines ((Leukoaminochroms)) I dessen Isolierung illusorisch zu machen schien, hat man andere Wege eingeschlagen, urn zu den interessanten und wenig erforschten Dihydroindol-Verbindungen zu gelangen (z. B. Synthese von 5,6-Dihydroxy-indolin [19], racemischer Indolin-2-carbonsaure [ZO] und racemischer 5,6-Dihydroxy-indolin-carbonsaure [21] [25] unter diesen Bedingungen racemisiert .…”

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Die Synthese von Cyclodopa (Leukodopachrom)

Wyler

Chiovini

1968

Helvetica Chimica Acta

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Summary. The synthesis of the methylester of cyclodopa (5.6-dihydroxy-indoline-2-carboxylic acid) is achieved by oxidative conversion of dopa methyl ester to dopachrome methyl ester and its subsequent reduction a t pH 8, using respectively potassium hexacyanoferrate(II1) and sodium dithionite. The efficiency of the oxidation step was found to be dependent on the rather low concentration of the reactants and the very short reaction time involved. After its production cyclodopa methyl ester was stabilized by immediate protonation followed by acetylation leading in a high yield to O,O, N-triacetyl cyclodopa methyl ester. By partial hydrolysis this derivative gives an 0, N-diacetyl cyclodopa methyl ester and further N-acetyl cyclodopa methyl ester. Cyclodopa methyl ester and cyclodopa are obtained by prolonged anaerobic hydrolysis. Micro-separation procedures, nmr-, uv-spectra and chiral-optical properties of cyclodopa and its derivatives are reported and discussed. It is shown by nmr evidence that under acidic conditions the aromatic proton on C(7) of cyclodopa slowly exchanges with deuterium. When an alcoholic solution of cyclodopa methyl ester and semicarbazide is allowed to oxidize in the air, the semicarbazone of dopachrome methyl ester forms.Einleitung. -Cyclodopa I a ist unter dem Namen ((Leukodopachrom H schon langer

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Studies related to the chemistry of melanins. Part III. Synthesis of 5,6-dihydroxyindoline

Cited by 6 publications

References 0 publications

Chemistry of Aminochromes. Part XV. The Reaction of Epinochrome with Thiols

Chemistry of Aminochromes. Part XV. The Reaction of Epinochrome with Thiols

Phosphane‐Free Pd⁰‐Catalyzed Cycloamination and Carbonylation with Pd(OAc)₂ and Cu(OAc)₂ in the Presence of K₂CO₃: Preparation of Benzocyclic Amines and Benzolactams

Die Synthese von Cyclodopa (Leukodopachrom)

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Studies related to the chemistry of melanins. Part III. Synthesis of 5,6-dihydroxyindoline

Cited by 6 publications

References 0 publications

Chemistry of Aminochromes. Part XV. The Reaction of Epinochrome with Thiols

Chemistry of Aminochromes. Part XV. The Reaction of Epinochrome with Thiols

Phosphane‐Free Pd0‐Catalyzed Cycloamination and Carbonylation with Pd(OAc)2 and Cu(OAc)2 in the Presence of K2CO3: Preparation of Benzocyclic Amines and Benzolactams

Die Synthese von Cyclodopa (Leukodopachrom)

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Phosphane‐Free Pd⁰‐Catalyzed Cycloamination and Carbonylation with Pd(OAc)₂ and Cu(OAc)₂ in the Presence of K₂CO₃: Preparation of Benzocyclic Amines and Benzolactams