Utilization of Polyphosphoric Acid in the Presence of a Co-solvent

Guy, Alain; Guette, J.‐P.; Lang, Gérard

doi:10.1055/s-1980-28974

Cited by 49 publications

(19 citation statements)

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“…A subsequent Fischer indole cyclization occurred on heating 5 at 120 °C for 18 h in the presence of polyphosphoric acid and xylene as co‐solvent to give 6 in 64% yield 13. During our investigations we encountered difficulties to hydrolyse the methyl ether by standard procedures at a later stage of the synthesis; therefore, we cleaved the methyl ether with AlCl 3 at this early point to switch to a benzyl ether as a more feasible protecting group.…”

Section: Resultsmentioning

confidence: 99%

A Concise and Efficient Synthesis of seco‐Duocarmycin SA

Tietze¹,

Haunert²,

Feuerstein³

et al. 2003

Eur J Org Chem

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A short and efficient synthesis of seco‐duocarmycin SA (3), a highly potent cytostatic agent and direct precursor of the natural product duocarmycin SA (1), has been achieved. Starting from commercially available 2‐methoxy‐4‐nitroaniline (4) the synthetic protocol contains a Fischer indole synthesis to introduce the heterocyclic scaffold and a radical 5‐exo‐trig cyclization to furnish the (chloromethyl)indoline ring system as key reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Section: Resultsmentioning

confidence: 99%

A Concise and Efficient Synthesis of seco‐Duocarmycin SA

Tietze¹,

Haunert²,

Feuerstein³

et al. 2003

Eur J Org Chem

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“…Alternatively we prepared 6 from o-nitroaniline or from ethyl 7-nitroindole 2-carboxylate (ACROS) by described procedures. [29,30] Analytical TLC was performed on 0.25 mm silica 60 coated aluminum foils with F 254 indicator (Merck). Preparative column chromatography was executed using silica gel (Merck 60, 0.063 ± 0.200 mm).…”

Section: Methodsmentioning

confidence: 99%

The 7-Nitroindole Nucleoside as a Photochemical Precursor of 2′-Deoxyribonolactone: Access to DNA Fragments Containing This Oxidative Abasic Lesion

et al. 2000

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On the basis of molecular modeling studies, the 7-nitroindole nucleoside 1 was selected as a suitable photochemical precursor for photochemical generation of the C1' deoxyribosyl radical under irradiation, which led to 2'-deoxyribonolactone. The nitro-indole nucleoside derivatives 1a and 1b were prepared and their conformation was determined by X-ray crystallography and NMR spectroscopy. The photoreaction of these nucleosides gave the corresponding deoxyribonolactone derivatives efficiently, with release of 7-nitrosoindole. This reaction was successfully applied to synthesis of oligonucleotides containing the deoxyribonolactone lesion.

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“…115 8C (Lit. : [88] N-Phenylbenzamide (7 c): Following the general procedure (82 8C, 48 h), benzamide (363 mg, 3 mmol) was coupled with iodobenzene (224 mL, 2 mmol) by using Cu 2 O (14.4 mg, 0.1 mmol), ligand 1 c (117 mg, 0.4 mmol), cesium carbonate (1.303 g, 4 mmol), activated and powdered 3 molecular sieves (600 mg), and DMF (1.2 mL). The crude residue was purified by flash chromatography on silica gel (gradient CH 2 Cl 2 /hexanes 50:50 to 100:0) to provide 359 mg (91 % yield) of the desired product as a colorless solid.…”

Section: -Phenyl-1h-imidazole (3 A)mentioning

confidence: 99%

Highly Efficient and Mild Copper‐Catalyzed N‐ and C‐Arylations with Aryl Bromides and Iodides

Cristau

Cellier

Spindler³

et al. 2004

Chemistry A European J

576

239

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Mild, efficient, copper-catalyzed N-arylation procedures for nitrogen heterocycles, amides, carbamates, and C-arylation procedures for malonic acid derivatives have been developed that afford high yields of arylated products with excellent selectivity. The N-arylation of imidazole with aryl bromides or iodides was found to be greatly accelerated by inexpensive, air-stable catalyst systems, combining catalytic copper salts or oxides with a set of structurally simple chelating ligands. The reaction was shown to be compatible with a broad range of aryl halides, encompassing sterically hindered, electron-poor, and electron-rich ones, providing the arylated products under particularly mild conditions (50-82 degrees C). The lower limit in ligand and catalyst loading and the scope of Ullmann-type condensations catalyzed by complexes bearing those ligands with respect to the nucleophile class have also been investigated. Chelating Schiff base Chxn-Py-Al (1c) generates a remarkably general copper catalyst for N-arylation of pyrrole, indole, 1,2,4-triazole, amides, and carbamates; and C-arylation of diethyl malonate, ethyl cyanoacetate, and malononitrile with aryl iodides under mild conditions (50-82 degrees C). The new method reported here is the most successful to date with regard to Ullmann-type arylation of some of these nucleophiles.

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Utilization of Polyphosphoric Acid in the Presence of a Co-solvent

Cited by 49 publications

References 0 publications

A Concise and Efficient Synthesis of seco‐Duocarmycin SA

A Concise and Efficient Synthesis of seco‐Duocarmycin SA

The 7-Nitroindole Nucleoside as a Photochemical Precursor of 2′-Deoxyribonolactone: Access to DNA Fragments Containing This Oxidative Abasic Lesion

Highly Efficient and Mild Copper‐Catalyzed N‐ and C‐Arylations with Aryl Bromides and Iodides

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