546. The disproportionation of dihydroisoquinolines

Brodrick, C. I.; Short, W. F.

doi:10.1039/jr9490002587

Cited by 11 publications

(3 citation statements)

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“…Generally, the existing methods for preparing these compounds are mainly based on a multi-step linear synthesis (Scheme 1a), in which the aryl groups are mainly introduced by the original aroyl-bearing substrates and the C=N bond is formed in the final step. [8][9][10][11][12][13][14] This strategy always causes synthetic dilemmas -if products with different 11-aryls are wanted, chemists will be forced to repeat the multi-step synthetic sequence for each of target products. As a consequence, the synthetic efficiency cannot be well secured.…”

Section: Introductionmentioning

confidence: 99%

Late-Stage Two-Step C11–H Arylation of Dibenzooxa/thiazepines

Yang¹,

et al. 2023

Synthesis

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A practical and efficient synthesis of 11-aryldibenzooxa/thiazepines is achieved, via a late-stage and two-step C11-H arylation of simple dibenzooxa/thiazepines. The adoption of Grignard addition and DDQ dehydrogenation allows for opera-tionally simple and chemically reliable, and step-efficient and high-yielding transformations. The two-step and one-pot procedures provide excellent yields. The gram-scale experiment demonstrates the promising synthetic potentials in large-scale applications, and the advantages of this method are also highlighted in the efficient synthesis of an H460TaxR inhibitor.

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Section: Introductionmentioning

confidence: 99%

Late-Stage Two-Step C11–H Arylation of Dibenzooxa/thiazepines

Yang¹,

et al. 2023

Synthesis

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“…At the same time in the reaction of 6,7-dimethoxy-3,4-dihydroisoquinoline 2 with o-hydroxybenzyl alcohols 4a,b in boiling o-xylene, in place of the products of C-alkylation or cycloaddition expected by us, 2-[(6,7-dimethoxy-3,4-dihydro-2(1H)-isoquinolinyl)methyl]phenols 5a,b were isolated. It might have been assumed that in boiling xylene, unlike in ethanol, disproportionation takes place initially of 6,7-dimethoxy-3,4-dihydroisoquinoline into 6,7-dimethoxyisoquinoline and 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline [10] and then further interaction with o-quinone methide, leading to the formation of phenols 5a,b. However, extended heating of 6,7-dimethoxy-3,4-dihydroisoquinoline (2) in boiling o-xylene in the absence of o-hydroxybenzyl alcohols does not lead to its disproportionation.…”

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confidence: 99%

Reactions of 6,7-dimethoxy- 3,4-dihydroisoquinoline with o-quinone methides

Osyanin

Ивлева

Osipov

et al. 2011

Chem Heterocycl Comp

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“…15 and 16 respectively). l-Phe11yl-3,4-dihydroisoquinoline is l~n o~v n to ~~nclergo a similar pyrolytic clisproportionatio~~ (17). Recently (18) such a disproportionation has been ascribed also to l-methyl-3,4-dihydro-0-carboline to account for the c11romatog1-aphic detection of I-111ethyl-p-carboline, l-metl1yl-3,-l-dil1~~dro-~-carboline, ancl I-methyl-1,2,:3,4-tetrahydro-0-carboline amongst the clistillation prodi~cts of 1-methyl-3,4-dil~ydro-~-carboli1~e-3-carboxylic acid.…”

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confidence: 99%

3,4-Dihydro-Β-Carbolines: II. THE EXHAUSTIVE METHYLATION OF 3,4-Dihydro-Β-Carboline

Gupta¹,

Spenser²

1962

Can. J. Chem.

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The n~ethiodide of 3,4-dihydro-0-carboline yields a dimeric anhydro base which, on heating, disproportionates to a 0-carboline and a tetrahydro-p-carboline derivative, and on nlethylation is co11verted to 3-[3-forrnylindolyl]-~-ethyltrin1ethylan1111oni~n iodide.Although a large number of 1-substituted 3,4-dihydro-@-carbolines have beell synthesized (1, 2), the parent base itself (11, R=H) has not been well characterized. 3,4-Dihydro-P-carboline was first obtained (3) by degradation of evodiainine. I t was isolated a s a tarry mass, which yielded a picrate, and was identified by oxidation to Pcarboline (4). Atteinptecl synthesis by conventioiial Bischler-Napieralslti ring closure of NB-forii~~7ltryptarnine (I, R = H ) gave an uiicharacterized product in 2y0 yield (2). The base was later obtained by this inethod in 36y0 yield as an amorphous powder of indeterminate melting point, yielding a picrate and a perchlorate (5).Crude 3,4-dihydro-p-carboline (11, R = H ) has now been obtained in SOY0 yield froill NB-forniyltryptarnine (I, R = H ) , using polyphosphoric acid as the dehydrating agent. The conipound resisted purification because of its sensitivity towards aqueous acid and its tendency to polymerization. Analysis of the free base was unsatisfactory. The inethiodide, however, showed the expected composition. 9-Methyl-3,4-dihydro-P-carboline (11, R = CHJ, obtained from N8-for~nyl-1-inethyltryptamine (I, R = CH3), behaved similarly. The ultraviolet absorption curves of both compounds (Fig. 1) were similar to those of 1-alkyl-3,4-dihydro-P-carbolines (6), and the infrared spectra were also consistent with the assigned structure.

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546. The disproportionation of dihydroisoquinolines

Cited by 11 publications

References 0 publications

Late-Stage Two-Step C11–H Arylation of Dibenzooxa/thiazepines

Late-Stage Two-Step C11–H Arylation of Dibenzooxa/thiazepines

Reactions of 6,7-dimethoxy- 3,4-dihydroisoquinoline with o-quinone methides

3,4-Dihydro-Β-Carbolines: II. THE EXHAUSTIVE METHYLATION OF 3,4-Dihydro-Β-Carboline

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