Plan
Comptes Rendus

Mémoire
Copper-catalyzed synthesis of diarylamines using p-toluene sulfonamides and benzhydrol derivatives under homogeneous borrowing hydrogen conditions
Comptes Rendus. Chimie, Volume 23 (2020) no. 1, pp. 47-55.

Résumé

Diarylamines were synthesized using p-toluene sulfonamides with benzhydrol derivatives in the presence of a copper/bisphosphine complex by Borrowing Hydrogen (BH) mechanism, yielding <98% under clean and mild reaction conditions. The use of readily available and cost-effective copper salts, short reaction times, high yield and reaction rates are highlighted.

Supplementary Materials:
Supplementary material for this article is supplied as a separate file:

Métadonnées
Reçu le :
Révisé le :
Accepté le :
Publié le :
DOI : 10.5802/crchim.5
Mots clés : Diaryl amine, Benzhydrol, sulfonamides, Copper salt, Bisphosphine ligands, Borrowing Hydrogen (BH) mechanism

Akram Ashouri 1 ; Saadi Samadi 1 ; Masoud Ahmadian 1 ; Behzad Nasiri 1

1 Laboratory of Asymmetric Synthesis, Department of Chemistry, Faculty of Science, University of Kurdistan, 66177-15175, Sanandaj, Iran
Licence : CC-BY 4.0
Droits d'auteur : Les auteurs conservent leurs droits
@article{CRCHIM_2020__23_1_47_0,
     author = {Akram Ashouri and Saadi Samadi and Masoud Ahmadian and Behzad Nasiri},
     title = {Copper-catalyzed synthesis of diarylamines using \protect\emph{p}-toluene sulfonamides and benzhydrol derivatives under homogeneous borrowing hydrogen conditions},
     journal = {Comptes Rendus. Chimie},
     pages = {47--55},
     publisher = {Acad\'emie des sciences, Paris},
     volume = {23},
     number = {1},
     year = {2020},
     doi = {10.5802/crchim.5},
     language = {en},
}
TY  - JOUR
AU  - Akram Ashouri
AU  - Saadi Samadi
AU  - Masoud Ahmadian
AU  - Behzad Nasiri
TI  - Copper-catalyzed synthesis of diarylamines using p-toluene sulfonamides and benzhydrol derivatives under homogeneous borrowing hydrogen conditions
JO  - Comptes Rendus. Chimie
PY  - 2020
SP  - 47
EP  - 55
VL  - 23
IS  - 1
PB  - Académie des sciences, Paris
DO  - 10.5802/crchim.5
LA  - en
ID  - CRCHIM_2020__23_1_47_0
ER  - 
%0 Journal Article
%A Akram Ashouri
%A Saadi Samadi
%A Masoud Ahmadian
%A Behzad Nasiri
%T Copper-catalyzed synthesis of diarylamines using p-toluene sulfonamides and benzhydrol derivatives under homogeneous borrowing hydrogen conditions
%J Comptes Rendus. Chimie
%D 2020
%P 47-55
%V 23
%N 1
%I Académie des sciences, Paris
%R 10.5802/crchim.5
%G en
%F CRCHIM_2020__23_1_47_0
Akram Ashouri; Saadi Samadi; Masoud Ahmadian; Behzad Nasiri. Copper-catalyzed synthesis of diarylamines using p-toluene sulfonamides and benzhydrol derivatives under homogeneous borrowing hydrogen conditions. Comptes Rendus. Chimie, Volume 23 (2020) no. 1, pp. 47-55. doi : 10.5802/crchim.5. https://comptes-rendus.academie-sciences.fr/chimie/articles/10.5802/crchim.5/

Version originale du texte intégral (Proposez une traduction )

1. Introduction

Amines play an important role in biological [12], pharmacological [3] and agricultural [4] activities. Hence the synthesis of substituted amines (the structural active motif of several drugs such as cetirizine [5], sertraline [6], rasagiline [7] and rivastigmine [8]) has been attracting increasing attention.

Scheme 1.

Different protocols for the conversion of alcohols to amines.

Alcohols are usually inexpensive substrates and available sources to prepare amines. They are usually converted to aldehydes [9], ketones [10], imines [11] or other related compounds before reacting with nucleophiles. Alongside all advances in rhodium catalyst addition of the organometallic reagents to imines producing diarylamine [12], numerous methods were reported in the literature, based on hydrogenation of imines and enamines [1314], amination of ketones and amination of alkyl halides [15] (Scheme 1). Amongst them, hydrogenation reactions are much more important in research or industry, and the use of either hydrogen gas or transfer hydrogenation reduction with Brønsted [16] or Lewis catalysts [171819] and transition metal complexes of Ir, Pd, Rh is well established [202122]. Notwithstanding many reports on these reactions, these multistep pathways often suffer from the instability of the intermediates, low atom economy and the production of byproducts. In addition, the drawbacks of Ir-, Pd-, Rh-based catalysts such as toxicity, high cost and metal leaching problems [23] have limited their broad utilization for these reactions. Using protocols which provide advantages regarding these limitations on an industrial scale is going to be a challenge.

In recent years, a green, economical and environmentally friendly protocol has been designed for producing substituted amines through a borrowing hydrogen reaction (BH methodology) [24] without the need for additional hydrogen sources. The main point of this reaction can be temporary storage of hydrogen, which is released from the nucleophilic substrate to the electrophilic metal catalyst during the gentle oxidation process. After the conversion of the oxidized intermediate to the C=X double bond intermediate, the metal-hydride catalyst returned hydrogen to the C=X double bond which is more electrophilic than the initial substrate. Hence, the development of an efficient catalytic BH methodology has attracted more attention in recent years. Furthermore, because of the stability of the metal-hydrid formed with second and third-row transition metal catalysts, which prevents return of the activated hydrogen [25], these metals are not suitable for BH methodology. Therefore, developing the use of active metals in these reactions has been much highlighted. In 2013, Singh and co-workers reported the conversion of primary benzylic alcohols to N-alkyl amines using Fe(II) phthalocyanine as catalyst [26]. In 2014, Feringa and Barta reported (cyclopentadienone)iron carbonyl as precatalyst for direct coupling of alcohols and amines through BH methodology [27]. In 2014, Zhao and coworkers reported a catalytic method for the amination of alcohols in the presence of an iridium complex and phosphoric acid. In 2018 Sunoj and co-workers reported the amination of alcohols in the presence of iridium-diamine complex and phosphoric acid [28]. In 2019, Barta and co-workers reported direct amination of benzyl alcohols using NH3 in the presence of Ni(OTf)2∕dcpp catalyst [29]. In 2019, Hofmann and Hultzsch also reported the N-alkylation of anilines with benzylic alcohols using the nitrile-ligated Knölker’s complex [30].

Scheme 2.

Preparation of diarylamines using p-toluene sulfonamides and benzhydrol derivatives in the presence of copper/bisphosphine complexes.

In this context, for the preparation of diarylamines in a clean, suitable and attractive BH methodology, we report a one-step reaction within benzhydrol derivatives and p-toluene sulphonamide in the presence of copper-bisphosphine complexes. This methodology benefits from the use of readily available and low cost copper salts, required no additional acids, bases or activation reagents to activate the alcohol, no hydrogen source and results in the formation of H2O as an only byproduct after 1 h (Scheme 2).

2. Experimental

2.1. Materials

All chemicals were purchased from Sigma-Aldrich or Merck Chemicals. Diethyl ether, tetrahydrofuran, and 1, 4-dioxane were distilled under nitrogen from benzophenone/sodium before use. Copper salts were dried overnight at 120 °C. Benzhydrol derivatives were prepared according to previously reported procedures [31]. 1H NMR and 13C NMR spectra were recorded on BrukerAvIII HD-500 MHz using TMS as an internal standard.

2.2. General procedure

The borrowing hydrogen process is achieved in a sealed Schlenk tube under argon atmosphere. Benzhydrol derivative (0.1 mmol), p-toluene sulfonamide (0.1 mmol), Cu(OTf)2 (5 mol%) and dppe (5 mol%) were dissolved in dried 1,4-dioxane (0.5 mL). The mixture was stirred for 1 h under reflux. After cooling to room temperature, the reaction mixture was passed through a short silica column (eluent ethyl acetate), and then the solvent was removed under reduced pressure. The obtained residue was purified by column chromatography (EtOAc–PE, 1:10) to afford the diarylated amines:

N-[(phenyl)phenylmethyl]-4- methylbenzenesulfonamide(3a)

White solid; yield: 346 mg (98%); mp 148–151 °C [32]: 1H NMR (500 MHz, CDCl3): δ 7.59 (d, J = 8.0 Hz, 2 H), 7.20–7.25 (m, 6 H), 7.10-7.17 (m, 6 H), 5.57 (d, J = 7.2 Hz, 1 H), 5.34 (d, J = 7.1 Hz, 1 H), 2.38 (s, 3 H); 13C NMR (100 MHz, CDCl3): 142.1, 139.5, 128.3, 127.5 (4 C), 127.3, 126.5 (2 C), 126.2 (4 C), 126.1 (2 C), 60.3, 20.4.

N-((4-chlorophenyl)(phenyl)methyl)-4-methylbenzenesulfonamide(3b)

White solid; yield: 367 mg (95%) mp 115–116 °C [33]. 1H NMR (500 MHz, CDCl3): δ 7.56 (d, J = 8.1 Hz, 2 H), 7.23–7.245 (m, 3 H), 7.16–7.23 (m, 4 H), 7.04–7.11 (m, 4 H), 5.54 (d, J = 6.9 Hz, 1 H), 5.10 (d, J = 6.9 Hz, 1 H), 2.42 (s, 3 H). 13C NMR (100 MHz, CDCl3) 141.2, 139.8, 139.6, 137.2, 133.1, 128.4, 127.6 (2 C), 127.6, 126.8, 126.1 (2 C), 59.6, 20.3.

N-((3-chlorophenyl)(phenyl)methyl)-4-methylbenzenesulfonamide(3c)

White solid; yield: 348 mg (90%); mp 126–128 °C [34].

N-((2-chlorophenyl)(phenyl)methyl)-4-methylbenzenesulfonamide(3d)

White solid; yield: 367 mg (95%) m.p. 171–172 °C [33]. 1H NMR (500 MHz, CDCl3): δ 7.62 (d, J = 8.2 Hz, 2H), 7.32 – 7.37 (m, 1H), 7.20 – 7.25 (m, 4H), 7.13 – 7.18 (m, 4H), 7.07 (dd, J = 7.0, 2.2 Hz, 2H), 5.92 (d, J = 7.2 Hz, 1H), 5.31 (d, J = 7.2 Hz, 1H), 2.38 (s, 3H).

N-((4-bromophenyl)(phenyl)methyl)-4-methylbenzenesulfonamide(3e)

White solid; yield: 389 mg (90%); mp 117–119 °C [35]. 1H NMR (500 MHz, CDCl3): δ 7.54 (d, J = 8.2 Hz, 2H), 7.32 (d, J = 8.5 Hz, 2H), 7.20 – 7.23 (m, 3H), 7.14 (d, J = 8.0 Hz, 2H), 7.05 (dd, J = 6.5, 2.9 Hz, 2H), 7.00 (d, J = 8.4 Hz, 2H), 5.52 (d, J = 7.1 Hz, 1H), 5.21 (d, J = 7.1 Hz, 1H), 2.39 (s, 3H).

N-((4-fluorophenyl)(phenyl)methyl)-4-methylbenzenesulfonamide(3f)

White solid; yield: 353 mg (95%); mp 123–124 °C [36]. 1H NMR (500 MHz, CDCl3): δ 7.55 (d, J = 8.3 Hz, 2H), 7.17 – 7.21 (m, 3H), 7.02 – 7.07 (m, 4H), 6.92 – 6.96 (m, 4H), 5.54 (d, J = 7.1 Hz, 1H), 5.16 (d, J = 7.0 Hz, 1H), 2.39 (s, 3H).

N-((4-methoxyphenyl)(phenyl)methyl)-4-methylbenzenesulfonamide(3g)

White solid; yield: 326 mg (85%); mp 126–128 °C [37].

4-methyl-N-((4-nitrophenyl)(phenyl)methyl) benzenesulfonamide(3h)

Light yellow solid; yield: 367 mg (92%); mp 125–126 °C [38]. 1H NMR (500 MHz, CDCl3): δ 7.58 (d, J = 8.1 Hz, 2H-Ar), 7.22–7.26 (m, 3H, Ar-H), 7.22–7.16 (m, 4H),7.10–7.04 (m, 4H) 5.55 (d, J = 6.9 Hz, 1H, NCH), 5.01 (d, J = 6.9 Hz, 1H, HN), 2.42 (s, 3H).

4-methyl-N-(phenyl(p-tolyl)methyl) benzenesulfonamide(3i)

White solid; yield: 312 mg (85%); mp 128–130 °C [33]. 1H NMR (500 MHz, CDCl3): δ 7.54 – 7.59 (m, 2H), 7.17 – 7.23 (m, 3H), 7.14 (d, J = 8.0 Hz, 2H), 7.08 – 7.12 (m, 2H), 6.99 (d, J = 8.1, 8.1 Hz, 4H), 5.52 (d, J = 7.0 Hz, 1H), 5.06 (d, J = 6.9 Hz, 1H), 2.38 (s, 3H), 2.28 (s, 3H).

4-methyl-N-(phenyl(4-(trifluoromethyl)phenyl) methyl)benzenesulfonamide(3j)

White solid; yield: 379 mg (90%); mp 122–124 °C [39]. 1H NMR (500 MHz, CDCl3): δ 2.35 (s, 3H), 5.34 (d, J = 7.2 Hz, 1H), 5.59 (d, J = 7.2 Hz, 1H), 7.01 – 7.05 (m, 2H), 7.10 (d, J = 8.0 Hz, 2H), 7.23 (s, 1H), 7.19 – 7.23 (m, 3H), 7.25 (s, 1H), 7.42 (d, J = 8.2 Hz, 2H), 7.51 (d, J = 8.3 Hz, 2H).

3. Results and discussion

Initially, the model reaction was carried out using benzhydrol (1a) (0.1 mmol), p-toluene sulphonamide (2) (0.1 mmol) in refluxing 1,4-dioxane under argon atmosphere with the trace formation of the desired product (3a) after 10 h. When the reaction was performed in presence of Cu(OTf)2, the rate of reaction increased and yields of 30% were obtained after 10 h.

In the next run, the reaction was done in the presence of Cu(OTf)2 (5 mol%), dppe (5 mol%) which allowed the rate and yield of reaction to significantly improve (98%) after 1 h. We optimized the conditions, screening numerous ligands and copper salts, solvents, the ratio of substrates, the amount of copper salts and ligands and also using a base to significantly decrease the reaction time. As the results showed (Table 1), the reactions performed using dppm, dppp and dppb show no significant conversion, while in the presence of PPh3, the desired product was obtained with 80% yield. Using (rac)-binap and (rac)-segphos the products were prepared with 85 and 90% yields respectively (Table 1, entries 2–7). Surprisingly, other copper salts could not promote the reaction (entries 8–13). The reaction also did not proceed in the presence of base, even non-coordinating bases (Table 1, entry 14). Under basic conditions, the formed metal-hydride/ H(OTf) catalyst becomes inactive and the reaction does not proceed.

Table 1.

Optimization of reaction conditions

  Entry a  Copper Salt  LigandYield (%)b
  1  Cu(OTf)2  dppe98
  2  Cu(OTf)2  dppmtrace
  3  Cu(OTf)2  dppptrace
  4  Cu(OTf)2  dppbtrace
  5  Cu(OTf)2  PPh 380
  6  Cu(OTf)2  (rac)-binap85
  7  Cu(OTf)2  (rac)-segphos90
  8c  Cu(OAC)2  dppe-
  9  CuCl2  dppe-
  10  CuCl  dppe-
  11  CuI  dppe-
  12  Cu(NO3)2.3H2O  dppe-
  13  Cu2O  dppe-
  14d  Cu(OTf)2  dppe-

aReaction conditions: benzhydrol (0.1 mmol), p-toluenesulfonamide (0.1 mmol), Dioxane (0.5 mL). bIsolated yields. cEntries 8–13 after 24 h, dKOH or K2CO3 were used.

Next, we investigated the effect of the solvent. In general, the BH reaction in common organic solvents progresses with low conversion towards the desired product. This can be due to insufficient imine reduction. The degree of stability of metal-hydride intermediate is crucial, which is directly affected by the solvent. If the metal-hydride intermediate is too stable, it cannot return hydride easily. If it is not stable enough, it cannot enter the catalytic cycle. Therefore, it appears that a weakly coordinating solvent may stabilize the metal-hydride intermediate to enhance the imine reduction step. As outlined in Table 2, no desired product was observed in tetrahydrofuran and water, while the reaction proceeded with high yields in dichloromethane or toluene (90% and 95%, respectively), but not as rapidly as in 1,4-dioxane which furnished the desired product in both excellent yield and rate.

The influence of the ratio of the substrate was evaluated on the yield and the rate of reaction. Increasing the amount of benzhydrol has no notable effect on the yield, but the reactivity and the rate of reaction decreased and unreacted alcohol was observed (Table 3). Next we studied the effect of the loading amounts of the catalytic system with the best result obtained using Cu(OTf)2 and dppe (1:1, 5 mol% of benzhydrol) (Table 4, entry 2). Subsequently, no reaction occurred at room temperature.

Table 2.

Effect of various solvents on the model reaction

Entry    SolventYield (%) b
1    Tetrahydrofuran-
2    H2O-
3    Dichloromethane90c
4    Toluene95d
5    1, 4-Dioxane98

aReaction conditions: benzhydrol (0.1 mmol), p-toluene sulfonamide (0.1 mmol), dppe, Cu(OTf)2, solvent (0.5 mL). cAfter 5 h). dAfter 2 h.

Scheme 3.

The proposed BH mechanism.

Table 3.

Effect of substrates ratio (benzhydrol to p-toluene sulfonamide)

Entry     Ratio (1a to 2)Time of reaction (h)
1     1:11
2     2:12
3     3:13
5     4:15

aReaction conditions: benzhydrol (a), p-toluene sulfonamide (b), dppe, Cu(OTf)2, dioxane (0.5 mL).

Table 4.

Effect of ratio (copper salt and ligand) on the model reaction

  Entry    x     yYield (%)b
  1    2     280
  2    5     598
  3    10     1060
  4    20     2053
  5    10     2070

aReaction conditions: Benzhydrol (0.1 mmol), p-toluenesulfonamide (0.1 mmol), Cu(OTf)2 (x), dppe (y), dioxane (0.5 mL).

We extended the optimum conditions to different benzhydrol derivatives. The results are presented in Table 5 and different substituted diarylamines were obtained in high to excellent yields (90–98%) under the optimal reaction conditions.

Under optimized condition, a BH mechanism is suggested in Scheme 3. In the presence of dppe-Cu(OTf)2 catalyst, benzhydrol is converted during the oxidation step to benzophenone which is more reactive in the nucleophilic reaction, resulting in generation of the dppe-Cu(OTf)-H/ H(OTf) catalyst. Then, benzophenone immediately reacted with the amide and an imine intermediate was produced.

Table 5.

Reaction scopea

aIsolated yield.

In the reductive step, the hydride was returned from the dppe-Cu(OTf)-H/ H(OTf) catalyst to the imine so that the desired product and Cu(OTf)2 catalyst were obtained. Due to the quick formation of the imine intermediate in the catalytic cycle, side reactions were completely suppressed and water is the only by-product [40]. Therefore, this methodology is a highly efficient and atom-economic method producing highly valuable amines for pharmaceutical and synthetic chemistry.

4. Conclusions

In conclusion, we developed a gentle, convenient, dynamically and kinetically efficient amidation of α-branched alcohols using p-toluene sulfonamide and benzhydrol derivatives in the presence of bisphosphine ligated Cu(OTf)2 as a good, first row-transition metal complex catalyst for BH methodology. Various substituted benzhydrols have been assembled effectively under racemic conditions with excellent yields in short reaction times. Further studies, including the development of an enantioselective procedure, are being actively pursued using other conditions by our research group.

Acknowledgments

We are grateful to the University of Kurdistan, Iran Research Councils for the support of this work.

Supplementary data

Supporting information for this article is available on the journal’s website under https://doi.org/10.5802/crchim.5 or from the author.


Bibliographie

[1] M. Mahdavi; S. Dianat; B. Khavari; S. Moghimi; M. Abdollahi; M. Safavi; A. Mouradzadegun; S. Kabudanian Ardestani; R. Sabourian; S. Emami Synthesis and biological evaluation of novel imidazopyrimidin-3-amines as anticancer agents, Chem. Biol. Drug Des., Volume 89 (2017), pp. 797-805 | DOI

[2] A. Gryshchenko; V. Bdzhola; A. Balanda; N. Briukhovetska; I. Kotey; A. Golub; T. Ruban; L. Lukash; S. Yarmoluk Design, synthesis and biological evaluation of N-phenylthieno [2, 3-d] pyrimidin-4-amines as inhibitors of FGFR1, Biorg. Med. Chem., Volume 23 (2015), pp. 2287-2293 | DOI

[3] K. J. French; Y. Zhuang; L. W. Maines; P. Gao; W. Wang; V. Beljanski; J. J. Upson; C. L. Green; S. N. Keller; C. D. Smith Pharmacology and antitumor activity of ABC294640, a selective inhibitor of sphingosine kinase-2, J. Pharmacol. Exp. Ther., Volume 333 (2010), pp. 129-139 | DOI

[4] K. Stella; F. Lynch; X. Ma; W. Lee; J. Hoppin; C. Christensen; G. Andreotti; L. Freeman; J. Rusiecki; L. Hou Heterocyclic aromatic amine pesticide use and human cancer risk: results from the US Agricultural Health Study, Int. J. Cancer, Volume 124 (2009), pp. 1206-1212

[5] D. A. Pflum; D. Krishnamurthy; Z. Han; S. A. Wald; C. H. Senanayake Asymmetric synthesis of cetirizine dihydrochloride, Tetrahedron Lett., Volume 43 (2002), pp. 923-926 | DOI

[6] D. Murdoch; D. McTavish Sertraline. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in depression and obsessive-compulsive disorder, Drugs, Volume 44 (1992), pp. 604-624

[7] V. Oldfield; G. M. Keating; C. M. Perry Rasagiline: a review of its use in the management of Parkinson’s disease, Drugs, Volume 67 (2007), pp. 1725-1747 | DOI

[8] C. M. Spencer; S. Noble Rivastigmine. A review of its use in Alzheimer’s disease, Drugs Aging, Volume 13 (1998), pp. 391-411

[9] N. Gogoi; G. Borah; P. K. Gogoi; T. R. Chetia TiO 2 supported gold nanoparticles: An efficient photocatalyst for oxidation of alcohol to aldehyde and ketone in presence of visible light irradiation, Chem. Phys. Lett., Volume 692 (2018), pp. 224-231 | DOI

[10] S. Guha; V. Rajeshkumar; S. S. Kotha; G. Sekar A versatile and one-pot strategy to synthesize α-amino ketones from benzylic secondary alcohols using N-bromosuccinimide, Org. Lett., Volume 17 (2015), pp. 406-409 | DOI

[11] A. Eizawa; S. Nishimura; K. Arashiba; K. Nakajima; Y. Nishibayashi Synthesis of ruthenium complexes bearing PCP-type pincer ligands and their application to direct synthesis of imines from amines and benzyl alcohol, Organometallics, Volume 37 (2018), pp. 3086-3092 | DOI

[12] G. Z. Zhao; G. Sipos; A. Salvador; A. Ou; P. Gao; B. W. Skelton; R. Dorta A chiral disulfoxide ligand for the efficient rhodium-catalyzed 1,2-addition of arylboroxines to N-tosylarylimines, Adv. Synth. Catal., Volume 358 (2016), pp. 1759-1766 | DOI

[13] D. C. Elliott; A. Marti; P. Mauleon; A. Pfaltz H 2 activation by non-transition-metal systems: Hydrogenation of aldimines and ketimines with LiN(SiMe 3 ) 2 , Chemistry, Volume 25 (2019), pp. 1918-1922 | DOI

[14] Y. V. Popov; V. Mokhov; S. Latyshova; D. Nebykov; A. Panov; T. Davydova Colloidal and nanosized catalysts in organic synthesis: XX. Continuous hydrogenation of imines and enamines catalyzed by nickel nanoparticles, Russ. J. Gen. Chem., Volume 88 (2018), pp. 2035-2038 | DOI

[15] A. Nodzewska; K. Sidorowicz; M. Sienkiewicz Solvent-free synthesis of a secondary N-benzhydrylamine as a chiral reagent for asymmetric deprotonation of bicyclic N-benzylamino ketones, Synthesis, Volume 46 (2014), pp. 1475-1480 | DOI

[16] L. Li; A. Zhu; Y. Zhang; X. Fan; G. Zhang Fe 2 (SO 4 )3 · xH 2 O on silica: an efficient and low-cost catalyst for the direct nucleophilic substitution of alcohols in solvent-free conditions, RSC Adv., Volume 4 (2014), pp. 4286-4291 | DOI

[17] J.-J. Yu; L.-M. Wang; F.-L. Guo; J.-Q. Liu; Y. Liu; N. Jiao Solvent-free amination of secondary benzylic alcohols with N-nucleophiles catalyzed by FeCl 3 , Synth. Commun., Volume 41 (2011), pp. 1609-1616

[18] T. Ohshima; J. Ipposhi; Y. Nakahara; R. Shibuya; K. Mashima Aluminum triflate as a powerful catalyst for direct amination of alcohols, including electron-withdrawing group-substituted benzhydrols, Adv. Synth. Catal., Volume 354 (2012), pp. 2447-2452 | DOI

[19] T. Verdelet; R. M. Ward; D. G. Hall Direct sulfonamidation of primary and secondary benzylic alcohols catalyzed by a boronic acid/oxalic acid system, Eur. J. Org. Chem., Volume 2017 (2017), pp. 5729-5738 | DOI

[20] Z.-J. Yao; N. Lin; X.-C. Qiao; J.-W. Zhu; W. Deng Cyclometalated half-sandwich iridium complex for catalytic hydrogenation of imines and quinolines, Organometallics, Volume 37 (2018), pp. 3883-3892 | DOI

[21] M. Lautens; E. M. Larin Pd/Zn-catalyzed asymmetric transfer hydrogenation of imines with alcohols, Synfacts, Volume 14 (2018), 0730 pages

[22] H. Zhang; X. Zhao; D. Chen A computational investigation of the hydrogenation of imines catalyzed by rhodium thiolate complexes, Int. J. Quantum Chem., Volume 115 (2015), pp. 1-5 | DOI

[23] T. Sawano; P. Ji; A. R. McIsaac; Z. Lin; C. W. Abney; W. Lin The first chiral diene-based metal-organic frameworks for highly enantioselective carbon-carbon bond formation reactions, Chem. Sci., Volume 6 (2015), pp. 7163-7168 | DOI

[24] D. Hollmann Advances in asymmetric borrowing hydrogen catalysis, ChemSusChem, Volume 7 (2014), pp. 2411-2413 | DOI

[25] K. F. Hirsekorn; E. B. Hulley; P. T. Wolczanski; T. R. Cundari Olefin substitution in (silox)3M(olefin) (silox  = (t)Bu 3 SiO; M  = Nb, Ta): the role of density of states in second vs third row transition metal reactivity, J. Am. Chem. Soc., Volume 130 (2008), pp. 1183-1196 | DOI

[26] M. Bala; P. K. Verma; U. Sharma; N. Kumar; B. Singh Iron phthalocyanine as an efficient and versatile catalyst for N-alkylation of heterocyclic amines with alcohols: one-pot synthesis of 2-substituted benzimidazoles, benzothiazoles and benzoxazoles, Green Chem., Volume 15 (2013), pp. 1687-1693 | DOI

[27] T. Yan; B. L. Feringa; K. Barta Direct N-alkylation of unprotected amino acids with alcohols, Sci. Adv., Volume 3 (2017), eaao6494 pages

[28] S. Tribedi; C. M. Hadad; R. B. Sunoj Origin of stereoselectivity in the amination of alcohols using cooperative asymmetric dual catalysis involving chiral counter-ions, Chem. Sci., Volume 9 (2018), pp. 6126-6133 | DOI

[29] Y. Liu; A. Afanasenko; S. Elangovan; Z. Sun; K. Barta Primary benzylamines by efficient N-alkylation of benzyl alcohols using commercial Ni catalysts and easy-to-handle ammonia sources, ACS Sustain. Chem. Eng., Volume 7 (2019), pp. 11267-11274 | DOI

[30] N. Hofmann; K. C. Hultzsch Switching the N-alkylation of arylamines with benzyl alcohols to imine formation enables the one-pot synthesis of enantioenriched α-N-alkylaminophosphonates, Eur. J. Org. Chem., Volume 2019 (2019), pp. 3105-3111 | DOI

[31] F. Mo; L. J. Trzepkowski; G. Dong Synthesis of ortho-acylphenols through the palladium-catalyzed ketone-directed hydroxylation of arenes, Angew. Chem. Int. Ed., Volume 51 (2012), pp. 13075-13079 | DOI

[32] J. Pan; J.-q. Li; R.-f. Huang; X.-h. Zhang; H. Shen; Y. Xiong; X.-m. Zhu Metal-free direct N-benzylation of sulfonamides with benzyl alcohols by employing boron trifluoride-diethyl ether complex, Synthesis, Volume 47 (2015), pp. 1101-1108

[33] F. Han; L. Yang; Z. Li; C. Xia Sulfonic acid-functionalized ionic liquids as metal-free, efficient and reusable catalysts for direct amination of alcohols, Adv. Synth. Catal., Volume 354 (2012), pp. 1052-1060 | DOI

[34] T. Beisel; G. Manolikakes Palladium-catalyzed enantioselective three-component synthesis of α-substituted amines, Org. Lett., Volume 17 (2015), pp. 3162-3165 | DOI

[35] B. G. Das; R. Nallagonda; P. Ghorai Direct substitution of hydroxy group of π-activated alcohols with electron-deficient amines using Re 2 O 7 catalyst, J. Org. Chem., Volume 77 (2012), pp. 5577-5583 | DOI

[36] H. Dai; X. Lu Palladium (II)/2, 2 ' -bipyridine-catalyzed addition of arylboronic acids to N-tosyl-arylaldimines, Tetrahedron Lett., Volume 50 (2009), pp. 3478-3481 | DOI

[37] X. Fan; L.-A. Fu; N. Li; H. Lv; X.-M. Cui; Y. Qi Iron-catalyzed N-alkylation using π-activated ethers as electrophiles, Org. Biomol. Chem., Volume 11 (2013), pp. 2147-2153 | DOI

[38] S. Oi; M. Moro; H. Fukuhara; T. Kawanishi; Y. Inoue Rhodium-catalyzed addition of arylstannanes to carbon–heteroatom double bond, Tetrahedron, Volume 59 (2003), pp. 4351-4361 | DOI

[39] H. Shan; Q. Zhou; J. Yu; S. Zhang; X. Hong; X. Lin Rhodium-catalyzed asymmetric addition of organoboronic acids to aldimines using chiral spiro monophosphite-olefin ligands: Method development and mechanistic studies, J. Org. Chem., Volume 83 (2018), pp. 11873-11885 | DOI

[40] H. Liu; G. K. Chuah; S. Jaenicke Alumina-entrapped Ag catalyzed nitro compounds coupled with alcohols using borrowing hydrogen methodology, Phys. Chem. Chem. Phys., Volume 17 (2015), pp. 15012-15018 | DOI


Commentaires - Politique