A Practical Buchwald−Hartwig Amination of 2-Bromopyridines with Volatile Amines

Li, Jie Jack; Wang, Zhi; Mitchell, Lorna H.

doi:10.1021/jo070366v

Cited by 28 publications

(15 citation statements)

References 5 publications

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“…Arylamines are very important structural motif in organic synthesis due to their widespread applications in natural products, pharmaceuticals, agrochemicals, and advanced materials [4][5][6][7]. There are many chemicals and pharmaceutical intermediates with amine structural units, which are synthesized using the BHAR in the presence of a palladium catalyst system, representing the synthetic importance of this method in organic synthesis [8, area support.…”

Section: Introductionmentioning

confidence: 99%

Buchwald–Hartwig amination reaction using supported palladium on phosphine-functionalized magnetic nanoparticles

2015

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9]. Since the discovery of the BHAR (1995) [10,11], a range of modifications for this reaction has been developed to increase the reaction efficacy [12,13]. A survey in this field demonstrated that major advances have been obtained on developing new and more effective phosphorus ligands. The chemical structures of some of the used phosphorus ligands in BHAR are shown in Fig. 1 [14 -19]. It should be mentioned that some of these ligands have been showed high activity in BHAR.Despite the high activity of phosphorus ligands in metalcatalyzed organic reactions, they often suffer from some disadvantages, such as intrinsic toxicity, foul-smell, easy oxidization during reaction process, difficulty of extraction, tedious purification process, and lack of recoverability [20,21]. Stabilization of these ligands on a recyclable support is one of the most important approaches to improve their applicability in organic reactions [22][23][24]. However, separation and recovery of these ligands on solid supports usually required filtration or centrifugation; therefore, the efficiency of the recovered ligands can be somewhat reduced. In the recent years, magnetic nanoparticles (MNPs) have attracted much attention because of their easy preparation, large surface area ratio, facile separation by use of magnetic force, and low toxicity and price [25].Recently, in our research group, MNPs were functionalized using chlorodiphenylphosphine (ClPPh 2 ) and phosphine-functionalized magnetic nanoparticles (PFMN) as a recyclable phosphorus ligand were obtained [22]. Also, palladium (II) complex of PFMN ligand (Pd-PFMN) was prepared and its catalytic activity evaluated in the Heck reaction of chloroarenes. The results revealed that, this new catalyst showed high catalytic activity in the Heck reaction of chloroarenes [22]. This activity is attributed to the high reactivity of Pd complex involving phosphorus ligands and dispersible ability of MNPs in solution as a high surface Abstract The supported palladium on phosphine-functionalized magnetic nanoparticles (Pd-PFMN) was found to be an efficient magnetically separable catalyst for the Buchwald-Hartwig amination reaction (BHAR) under solvent-free conditions. All of the reactions in the presence of Pd-PFMN catalyst afforded the corresponding products in good to excellent yields. The catalyst can be easily separated from the reaction mixture using an external magnetic field, and it can be reused at least five cycles without significant loss in its initial catalytic activity.

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Section: Introductionmentioning

confidence: 99%

Buchwald–Hartwig amination reaction using supported palladium on phosphine-functionalized magnetic nanoparticles

2015

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“…Recently, the sealed-tube conditions have been revealed by Li et al as a good expedient for the amination reaction with volatile amines to provide aromatic amines that could not be obtained by the straightforward reaction. 7 The outline of synthetic pathways for 2,6-diaminoazulene derivatives is shown in Scheme 1. The reaction conditions and yield of the products are summarized in Table 1.…”

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Synthesis of 2,6-Diaminoazulenes by the SNAr Reaction with Cyclic Amines

Shoji¹,

Fujiwara²,

Maruyama³

et al. 2015

HETEROCYCLES

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2-Amino-6-bromoazulene derivatives reacted with cyclic amines (pyrrolidine, piperidine and morpholine) under the sealed-tube conditions to afford the corresponding 2,6-diaminoazulenes in excellent yields. Aromatic compounds with multiple-amino functional groups have been of great interest owing to their potential applications in organic electronic devices, such as hole transport materials for organic light-emitting diodes. 1 Therefore, a large number of synthetic procedures for aromatic compounds with multiple-amino groups were found in literatures. 2 In the pioneering works of azulene chemistry by Nozoe et al., 2,6-diaminoazulenes were first synthesized from an aminotropolone derivative, but the procedure requires a multistep reaction for the preparation of the starting tropolone derivatives which are essential to the preparation of 2,6-diaminoazulenes with different amino functions. 3 They have also reported that the most promising intermediate, diethyl 2-amino-6-bromoazulene-1,3-dicarboxylate (1) that could be obtained much easier, does not react with † Dedicated to Professor Isao Kuwajima on the occasion of his 77th birthday

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“…to monoalkylated anilines with short-chain alkyl groups. For comparison, in the Buchwald-Hartwig reaction, these compounds have to be synthesized from the corresponding volatile amines using a sealed tube technique, 16 benzylmethylamine or methylammonium chloride. 17 Instead of ethylamine (bp, 16.6 1C), propylamine (bp, 48 1C), isopropylamine (bp, 33.5 1C), we are able to use the convenient non-volatile triethylamine, dipropylamine and diisopropylamine (Table 1, entries 1-3).…”

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N-Dealkylation of aliphatic amines and selective synthesis of monoalkylated aryl amines

et al. 2008

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A Practical Buchwald−Hartwig Amination of 2-Bromopyridines with Volatile Amines

Abstract: A practical Buchwald-Hartwig amination of 2-bromopyridines with volatile amines is developed in sealed tubes. The method provides an expedient entry to a variety of secondary and tertiary aminopyridines that are otherwise not readily synthesized.

Cited by 28 publications

References 5 publications

Buchwald–Hartwig amination reaction using supported palladium on phosphine-functionalized magnetic nanoparticles

Buchwald–Hartwig amination reaction using supported palladium on phosphine-functionalized magnetic nanoparticles

Synthesis of 2,6-Diaminoazulenes by the SNAr Reaction with Cyclic Amines

N-Dealkylation of aliphatic amines and selective synthesis of monoalkylated aryl amines

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