311. Indoles. Part II. The preparation and oxidation of the Bz-nitro-2-methyl-3-ethyl-, -2 : 3-diphenyl-, and -2-methyl-3-phenyl-indoles

Schofield, K.; Theobald, R. S.

doi:10.1039/jr9500001505

Cited by 12 publications

(7 citation statements)

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“…The yields were excellent for Ph-and methyl substituted indoles, but were low for other alkyl substituents (e.g. substrates 42, 44) (Scheme 10) [20][21].…”

Section: Oxidation With Ozonementioning

confidence: 97%

The Witkop-Winterfeldt-Oxidation of Indoles

Mentel¹,

Breinbauer

2007

COC

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In the early 1950s Witkop described in a series of papers that oxidation of indoles with a variety of oxidation reagents leads to the formation of quinolones. The mechanism of this reaction involves the oxidative cleavage of the 2,3-double bond of the indole moiety (Witkop-oxidation) followed by a Camps-cyclization forming the quinolone ring. Winterfeldt identified conditions which allow a one pot Witkop-oxidation/Camps-cyclization sequence and applied this strategy for the synthesis of pyrrolo[2,3-c]quinolones starting from 1,2,3,4-tetrahydro--carbolines. This review gives a comprehensive description of all described examples of this reaction including a definition of scope and limitations and a discussion of the mechanism of this transformation.

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“…The yields were excellent for Ph-and methyl substituted indoles, but were low for other alkyl substituents (e.g. substrates 42, 44) (Scheme 10) [20][21].…”

Section: Oxidation With Ozonementioning

confidence: 97%

The Witkop-Winterfeldt-Oxidation of Indoles

Mentel¹,

Breinbauer

2007

COC

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“…In the case of methyl ketone phenylhydrazones (LXXXVII, R = R" = H, R' = CHS, R'" = alkyl or substituted alkyl, CeH6, COOCsHe) it is well established (50, 79, 89, 124,126,163,164,168,204,205) that indolization gives exclusively the corresponding 3-substituted 2-methylindoles (LXXXVIII).…”

Section: Limitations In the Use Of Dehydrogenating Agents In The Bors...mentioning

confidence: 99%

“…tion, which gives a 1-monoacetyl and 1,3-diacetyl derivative, respectively (50); (ii) 3-monomethylation, which gives a basic 3-alkyl-2,3-dimethyl-3Hindole (XC, R = CH3, R' = alkyl) and a non-basic 2-alkyl-3-methylindole (XCI, R = alkyl), respectively (65, 79, 90, 93, 96); (iii) oxidative scission of the indolic 2,3-C=C to yield known substituted benzene derivative (163,204,205); (iv) unambiguous synthesis of the indole formed by the indolization (124).…”

Section: Limitations In the Use Of Dehydrogenating Agents In The Bors...mentioning

confidence: 99%

The Fischer Indole Synthesis.

Robinson¹

1963

Chem. Rev.

520

226

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“…(f) 4,4,8.1 mmol) in THF (50 mL) and potassamide (from 5.5 g, 141 mmol, of potassium) in ammonia (700 mL) gave (4 h; 5 g of NH4C1) a yellow solid K and an aqueous solution. Solid K crystallized from ethanol to give 4,4'-dinitrostilbene: 1.6 g, 5.9 mmol, 73%; mp 292-293 °C; mass spectrum, m/e (rel intensity) 270 (M+, 32), 254 (M -0, 5), 240 (M -NO, 31), 210 (M -2 -NO, 100).…”

Section: Methodsmentioning

confidence: 99%

“…When 4-nitrodiphenyl sulfone in ethanol was treated with potassamide in ammonia, competitive substitution reactions occurred, leading to 4-ethoxydiphenyl sulfone and 4-ethoxynitrobenzene, with the former predominating; however, the corresponding amino compounds were produced when tetrahydrofuran was used as cosolvent. 4 sulfoxide reacted less cleanly under these conditions to give 4-nitroaniline and diphenyl disulfide 2-and 4-Nitrotoluenes were next examined. 2-Nitrotoluene gave 2,2'-dinitrobibenzyl, and 4-nitrotoluene similarly gave 4,4'-dinitrobibenzyl, together with 4,4'-dinitro-stilbene as a byproduct.…”

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confidence: 99%