A simple, rapid, and efficient N-Boc protection of amines under ultrasound irradiation and catalyst-free conditions

Amira, Aïcha; K’tir, Hacène; Berredjem, Malika; Aouf, Nour‐Eddine

doi:10.1007/s00706-013-1094-4

Cited by 22 publications

(9 citation statements)

References 40 publications

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“…6,7 The Boc-masking group is installed by reacting the amino-substrate with di-tert-butyl dicarbonate under basic conditions, [8][9][10] or solvent free conditions. [11][12][13] Traditional approaches for N-Boc deprotection relies largely on TFA-induced cleavage. 14 Other strategies reported for the deprotection of N-Boc include the use of metal catalysts, 15,16 as well as acetylchloride in methanol, 17 N-Boc removal with HCl in organic solvents: ethylacetate, 18 dioxane, 19 in acetone.…”

Section: Introductionmentioning

confidence: 99%

Mild deprotection of the N-tert-butyloxycarbonyl (N-Boc) group using oxalyl chloride

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Mild deprotection of the N-tert-butyloxycarbonyl (N-Boc) group using oxalyl chloride

et al. 2020

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“…This experiment was carried out in accordance with works that report that the 3-arylation of indazole requires the previous N 1 -protection of the NH group due to the competing N 1 -arylation reaction [ 16 , 29 ]. It is noteworthy to mention that the previously reported N -protection procedures apply ultrasound irradiation on aliphatic or aromatic amine substrates [ 30 ], which are inherently more basic than N -heterocyclic rings. On the other hand, experimental procedures that employ indazole as a substrate for N -protection use standard basic conditions, namely DMAP/Et 3 N in acetonitrile [ 18 , 31 ].…”

Section: Resultsmentioning

confidence: 99%

Suzuki-Type Cross-Coupling Reaction of Unprotected 3-Iodoindazoles with Pinacol Vinyl Boronate: An Expeditive C-3 Vinylation of Indazoles under Microwave Irradiation

et al. 2018

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Herein we report an expeditive C-3 vinylation of unprotected 3-iodoindazoles under microwave irradiation. Ten C-5 substituted 3-vinylindazole derivatives, nine of them novel, were synthesized through this method, which proceeds in moderate to excellent yields starting from C-5 substituted 3-iodoindazole derivatives. In all cases, the C-3 vinylated derivative was the only isolated product. This methodology allows access to 3-vinylated indazoles selectively and directly without the need of N-protection. 3-Vinylindazoles could be interesting synthetic intermediates allowing access to biologically active molecules.

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“…The reaction was performed according to the protocol of Amira et al 20 L-Phenylalanine tert-butyl ester hydrochloride (2.50 g, 9.70 mmol) was stirred with sat. K 2 CO 3 (100 mL) for 2 min and the mixture was extracted three times with CH 2 Cl 2 .…”

Section: Boc-phe-otbu (1)mentioning

confidence: 99%

2-[18F]Fluorophenylalanine: Synthesis by Nucleophilic 18F-Fluorination and Preliminary Biological Evaluation

et al. 2019

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2-[18F]Fluorophenylalanine (2-[18F]FPhe), a promising PET tracer for imaging of cerebral infarction and tumors, was efficiently prepared from an easily accessible iodonium salt precursor using Cu-mediated radiofluorination under ‘low base’ or ‘minimalist’ conditions. Whereas significant racemization was initially observed if the ‘minimalist’ protocol was applied for radiolabeling, it was completely suppressed by the careful adjustment of 18F– preprocessing. The initial biological study revealed a higher uptake of 2-[18F]FPhe in different tumor cells in comparison to that of [18F]FET. In contrast to 4-[18F]FPhe, which suffered from rapid defluorination in vivo, 2-[18F]FPhe demonstrated a sufficient in vivo stability. Conclusively, 2-[18F]FPhe is a promising PET probe that is now readily available using Cu-mediated radiofluorination under ‘minimalist’ or ‘low base’ conditions. The simplicity of the translation of the proposed procedures to automated synthesis modules allows a broad biological evaluation of 2-[18F]FPhe. Notably, a novel protocol for the preparation of N-Boc protected amino acids from the respective Ni-Schiff base complexes was developed that avoided application of strongly acidic conditions.

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A simple, rapid, and efficient N-Boc protection of amines under ultrasound irradiation and catalyst-free conditions

Cited by 22 publications

References 40 publications

Mild deprotection of the N-tert-butyloxycarbonyl (N-Boc) group using oxalyl chloride

Mild deprotection of the N-tert-butyloxycarbonyl (N-Boc) group using oxalyl chloride

Suzuki-Type Cross-Coupling Reaction of Unprotected 3-Iodoindazoles with Pinacol Vinyl Boronate: An Expeditive C-3 Vinylation of Indazoles under Microwave Irradiation

2-[18F]Fluorophenylalanine: Synthesis by Nucleophilic 18F-Fluorination and Preliminary Biological Evaluation

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