View PDF Version
 
DOI: 10.1039/D4CY00812J (Paper) Catal. Sci. Technol., 2024, Advance Article

Efficient reductive amination of 5-hydroxymethylfurfural by iridium-catalysed transfer hydrogenation†

Haoying Liua, Weijun Tang*a, Dong Xuea, Jianliang Xiaob and Chao Wang*a
aKey Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710062, China. E-mail: tangwj@snnu.edu.cn; c.wang@snnu.edu.cn
bDepartment of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK

Received 29th June 2024 , Accepted 5th August 2024

First published on 10th August 2024

Abstract

Transfer hydrogenative reductive amination of 5-(hydroxymethy)furfural (HMF) has been accomplished, catalysed by a cyclometalated iridium catalyst with formic acid as a hydrogen source. The catalytic system afforded a TON of 9600 and TOF of 14[thin space (1/6-em)]400 h−1, and the reaction can be successfully scaled up to a 10 gram scale at a substrate-to-catalyst ratio of 10[thin space (1/6-em)]000. A wide range of amines could be coupled with HMF to afford furan derived products, including modified drug molecules, key intermediates for drug synthesis and potential monomers for polymer synthesis.

Introduction

HMF is an important biomass platform molecule derived from cellulose. Tremendous efforts have been made to transform HMF into value-added chemicals. Various reactions, including selective oxidation,1,2 hydrogenation,3,4 esterification,5,6 acetalization,7 and condensation,8 have been developed to convert HMF into a diverse range of compounds, including furan derivatives, fuel additives, diols, dicarboxylic acids, and hydrocarbons.9 The amination of HMF would produce amino furan compounds, which could serve as core structures in many drug and bioactive molecules (Scheme 1a). However, methods for amination of HMF are relatively underdeveloped. The development of green and efficient methods for the amination of HMF is highly sought after.
image file: d4cy00812j-s1.tif
Scheme 1 Application and synthesis of amino furan compounds.

Reductive amination of the aldehyde group of HMF provides a straightforward route for converting HMF into furan amine compounds. A range of reducing agents, including hydrogen,10–45 carbon monoxide/water,46 Zn/water47 and sodium borohydride,48 have been utilized as hydrogen sources for reductive amination of HMF (Scheme 1b). In addition, electrochemical reductive amination systems have been developed for amination of HMF.49,50 Nevertheless, the practical application of these reactions is hampered by the use of high-pressure hazardous gases, the generation of a stoichiometric amount of metal waste or the requirement of special electrochemical apparatus. It is still desirable to develop safe, green and operationally simple methods for the amination of HMF.

Reductive amination by transfer hydrogenation is an operationally simple approach. Although the reductive amination of simple aldehydes and ketones via transfer hydrogenation has been reported,51,52 the transfer hydrogenative reductive amination of HMF is rare. To the best of our knowledge, there are only two examples of reductive amination of HMF by transfer hydrogenation, which uses isopropanol (IPA) as hydrogen source.53,54 Formic acid is a biomass-derived small molecule, which has been considered as a sustainable hydrogen source.55–61 The by-product of using formic acid as a hydrogen source is carbon dioxide, which can be converted back to formic acid by hydrogenation. The use of formic acid for reductive amination of HMF has not been reported before. Herein, we report an efficient and scalable catalytic system for reductive amination of HMF with formic acid as a hydrogen source (Scheme 1c). The reaction can be performed with simple apparatus and only generates water and carbon dioxide as by-products.

Results and discussion

In our prior research, we have developed cyclometalated iridium complexes that exhibited remarkable reactivity and versatility in the reductive amination of carbonyl compounds62–64 and levulinic acid.65 We reckoned that the versatile cyclometalated iridium catalytic system might also be applicable for the selective reductive amination of HMF, despite the potential interference of the hydroxy group on HMF. The reaction of HMF with aniline, utilizing a formic acid–triethylamine azeotrope as the hydrogen source and catalysed by cyclometalated iridium complexes, was chosen as a model. Delightfully, when catalyst 1a (0.5 mol%), previously proven to be the most effective for RA, was employed, the desired selective amination product 3a was obtained in an NMR yield of 84% in methanol at 80 °C for 12 h. Subsequently, we explored the influence of solvents on the reaction. Non-proton solvents, such as toluene and cyclohexane, proved unfavourable, while THF and 1,4-dioxane also reduced the reaction's efficiency. Although some polar solvents allowed the reaction to proceed, methanol stood out as the optimal choice (see Table S1 in the ESI†). Interestingly, when the ratio of HMF to aniline was raised to 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8, the yield of 3a rose to 89% (Table 1, entries 1–5), possibly due to the excess amine promoting the formation of imine intermediates. Additionally, we synthesized a range of catalysts to test their performance in this reaction. Catalyst 1e, synthesized from cyclohexylamine and acetophenone, demonstrated the highest catalytic activity (Table 1, entries 6–9). Pure formic acid as the hydrogen source inhibited the reaction, while too much triethylamine also affected the yield negatively (see Table S2 in the ESI†). Crucially, the amount of hydrogen source played a pivotal role; the optimal reaction yield of 96% was achieved with 0.1 mL of F/T (Table 1, entries 10, 11). The reaction temperature was thoroughly examined as well. Lowering the reaction temperature resulted in a reduction in the reaction rate, while increasing the temperature did not yield any significant improvements in the reaction's efficiency (see Table S3 in the ESI†). Interestingly, there was only a small decrease in yield even when the reaction was carried out under an air atmosphere (Table 1, entry 12). The turnover number (TON) and turnover frequency (TOF) of the model reaction were examined. With HMF and aniline as reactants and 1e as the catalyst (Table 1, entry 13), a yield of 96% was achieved in 2 h at a S/C of 10[thin space (1/6-em)]000 as confirmed by 1H NMR spectroscopy, corresponding to a TON of 9600. And a TOF of 14[thin space (1/6-em)]400 h−1 was recorded in 10 min (Table 1, entry 14). These results position our catalytic system as one of the most effective homogeneous catalytic systems for the reductive amination of HMF.
Table 1 Optimization of reaction conditionsa

image file: d4cy00812j-u1.tif
Entry Catalyst HMF[thin space (1/6-em)]:[thin space (1/6-em)]amines F/Tb (mL) Yieldc (%)
a Reaction conditions: HMF (0.5 mmol, 1 equiv.), catalyst (0.5 mol%), MeOH (3 mL), 80 °C, N2, 12 h.b F/T = formic acid–triethylamine (5[thin space (1/6-em)]:[thin space (1/6-em)]2) azeotrope.c The yield was determined by 1H NMR with 1,3,5-trimethoxybenzene as an internal standard.d Under air atmosphere.e S/C = 10[thin space (1/6-em)]000, reaction time = 120 min.f S/C = 10[thin space (1/6-em)]000, reaction time = 10 min.
1 1a 1[thin space (1/6-em)]:[thin space (1/6-em)]1 0.5 84
2 1a 1.8[thin space (1/6-em)]:[thin space (1/6-em)]1 0.5 53
3 1a 2[thin space (1/6-em)]:[thin space (1/6-em)]1 0.5 44
4 1a 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.5 89
5 1a 1[thin space (1/6-em)]:[thin space (1/6-em)]2 0.5 85
6 1b 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.5 78
7 1c 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.5 92
8 1d 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.5 90
9 1e 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.5 93
10 1e 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 1.0 92
11 1e 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.1 96
12d 1e 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.1 85
13e 1e 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.1 96
14f 1e 1[thin space (1/6-em)]:[thin space (1/6-em)]1.8 0.1 24
image file: d4cy00812j-u2.tif

With the optimal reaction conditions established, we explored the substrate scope for amines (Scheme 2). The reaction exhibited remarkable tolerance to both steric hindrance and electronic effects within the phenyl ring for aromatic amines. Electron-donating and electron-withdrawing substituents at the ortho-, meta-, and para-positions of the phenyl ring of aromatic amines (3a–3t) were well tolerated, resulting in good yields. However, amines bearing strong electro-withdrawing substituents, such as the nitro group, m-methoxy group, and m-benzyloxy group (3n, 3s, and 3t), exhibited moderate activities, presumably due to their reduced nucleophilicity. Aromatic amines with naphthyl, di-substituted phenyl, and tri-substituted phenyl groups were also viable substrates (3u–3z). Additionally, a range of benzylamines and aliphatic amines yielded the target products with moderate yields (3aa–3ad). Secondary amines and amino-alcohols (3ae–3al) also underwent smooth transformation under standard conditions. This protocol could even extend to the modification of natural products and drugs, as demonstrated by the functionalization of tryptamine, cytisine, aminoglutethimide, and amantadine (3am–3ap). Unfortunately, amino acids failed to yield any product when used as amine sources, likely due to the influence of the carboxylic group.


image file: d4cy00812j-s2.tif
Scheme 2 Substrate scope of amines. Reaction conditions: HMF (0.5 mmol), amines (0.9 mmol), 1e (0.5 mol%), HCOOH/Et3N azeotrope (F/T, 0.1 mL), MeOH (3 mL), 80 °C, N2, 12 h. [a] Reaction time = 24 h.

To demonstrate the synthetic applicability of this protocol, a gram-scale preparation of 3a and 3af, along with the synthetic transformation of products 3l and 3af, were successfully conducted (Scheme 3). As shown in Scheme 3a, the reaction of HMF (10 mmol) with aniline (18 mmol) using only 0.01 mol% catalyst (S/C = 10[thin space (1/6-em)]000), without extending the reaction time, yielded product 3a in a 92% isolated yield. Subsequently, we scaled up the reaction to a larger scale, using 12.6 g of HMF (100 mmol) and aniline (180 mmol) with 0.01 mol% catalyst for 12 h (Scheme 3a, left). Delightfully, there was only a minor decrease in the yield of 3a, achieving an 83% isolated yield (16.86 g). Furthermore, 3af, an intermediate for the synthesis of drug molecules and bioactive compounds, can be produced in a single step by reacting HMF with dimethylamine. This reaction can be conveniently scaled up to 10 g using 0.01 mol% of the catalyst for 12 h (Scheme 3a, right). Moreover, once the reaction is complete, the desired product 3af can be isolated in a satisfactory yield of 85% (13.18 g) through simple extraction/evaporation processes (Scheme 3a, right). Notably, product 3af could undergo a substitution reaction with cysteamine hydrochloride in concentrated hydrochloric acid, converting it into 3aq, a vital intermediate for the synthesis of ranitidine and CPA-1. Subsequently, 3aq was reacted with N-methyl-1-(methylthio)-2-nitroethylen-1-amine to produce ranitidine in a 10 gram-scale, yielding 13.5 g of ranitidine (43% overall yield from HMF, Scheme 3b, top left). Ranitidine has traditionally been synthesized from furfuryl alcohol through the Mannich reaction in previous reports.66,67 The synthetic methods for ranitidine from HMF developed here provide an alternative route starting from a biomass platform molecule. By replacing N-methyl-1-(methylthio)-2-nitroethylen-1-amine with 3-chloro-4-methylphenyl isocyanate, we successfully converted 3aq into CPA-1, a bioactive molecule exhibiting anti-HIV properties (Scheme 3b, top right). This approach not only reduces the synthetic route for CPA-1 from five steps to three, but also eliminates the need for employing strong bases.68 In addition, product 3l could be transformed into a diamine compound 3at through a borrowing hydrogen reaction developed by us69 with an aryl amine catalyzed by 1e, which is the same catalyst for reductive amination of HMF. Compound 3at could serve as a potential polymer monomer for polymerization reactions in the synthesis of MOP or COF materials (Scheme 3b).70,71 Product 3a could also serve as an intermediate for the synthesis of a GPR55 agonist molecule.72


image file: d4cy00812j-s3.tif
Scheme 3 Gram-scale synthesis and transformation of products. For reaction details, see the ESI.†

Conclusions

In summary, we have developed an iridium-catalysed reductive amination reaction of HMF through a transfer hydrogenation process, using a formic acid–triethylamine azeotrope (F/T) as the hydrogen source. Both aromatic and aliphatic amines can be efficiently converted with good yields. The catalytic system gives a TON of 9600 and a TOF of 14[thin space (1/6-em)]400 h−1, and the reaction can be scaled up to ten grams. The protocol offers alternative routes for the synthesis of drug molecule ranitidine and bioactive molecule CPA-1 from biomass platform molecule HMF. The reductive amination of HMF might also have other applications in material and pharmaceutical sciences.

Data availability

The data supporting this article have been included as part of the ESI.†

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

This research was supported by the National Natural Science Foundation of China (no. 22172096), the Fundamental Research Funds for the Central Universities (no. GK202307007 and GK202002003), the Projects for the Academic Leaders and Academic Backbones, Shaanxi Normal University (no. 16QNGG008), the Natural Science Basic Research Program of Shaanxi (no. 2021JC-30), and the 111 project (B14041).

Notes and references

  1. Y. Liu, H.-Y. Ma, D. Lei, L.-L. Lou, S. Liu, W. Zhou, G.-C. Wang and K. Yu, ACS Catal., 2019, 9, 8306–8315 CrossRef CAS .
  2. L. Ardemani, G. Cibin, A. J. Dent, M. A. Isaacs, G. Kyriakou, A. F. Lee, C. M. A. Parlett, S. A. Parry and K. Wilson, Chem. Sci., 2015, 6, 4940–4945 RSC .
  3. S. Zhang, H. Ma, Y. Sun, Y. Luo, X. Liu, M. Zhang, J. Gao and J. Xu, Green Chem., 2019, 21, 1702–1709 RSC .
  4. Q. Deng, R. Gao, X. Li, J. Wang, Z. Zeng, J.-J. Zou and S. Deng, ACS Catal., 2020, 10, 7355–7366 CrossRef CAS .
  5. S. Alipour, H. Omidvarborna and D.-S. Kim, Renewable Sustainable Energy Rev., 2017, 71, 908–926 CrossRef CAS .
  6. M. J. Climent, A. Corma and S. Iborra, Green Chem., 2014, 16, 516–547 RSC .
  7. S. Kanai, I. Nagahara, Y. Kita, K. Kamata and M. Hara, Chem. Sci., 2017, 8, 3146–3153 RSC .
  8. H. Chang, A. H. Motagamwala, G. W. Huber and J. A. Dumesic, Green Chem., 2019, 21, 5532–5540 RSC .
  9. Q. Hou, X. Qi, M. Zhen, H. Qian, Y. Nie, C. Bai, S. Zhang, X. Bai and M. Ju, Green Chem., 2021, 23, 119–231 RSC .
  10. Z. Xu, P. Yan, W. Xu, S. Jia, Z. Xia, B. Chung and Z. C. Zhang, RSC Adv., 2014, 4, 59083–59087 RSC .
  11. M. Chatterjee, T. Ishizaka and H. Kawanami, Green Chem., 2016, 18, 487–496 CAS .
  12. Z. Xu, P. Yan, K. Liu, L. Wan, W. Xu, H. Li, X. Liu and Z. C. Zhang, ChemSusChem, 2016, 9, 1255–1258 CrossRef CAS PubMed .
  13. T. Komanoya, T. Kinemura, Y. Kita, K. Kamata and M. Hara, J. Am. Chem. Soc., 2017, 139, 11493–11499 CrossRef CAS PubMed .
  14. W. Chen, Y. Sun, J. Du, Z. Si, X. Tang, X. Zeng, L. Lin, S. Liu and T. Lei, J. Chem. Technol. Biotechnol., 2018, 93, 3028–3034 CrossRef CAS .
  15. A. García-Ortiz, J. D. Vidal, M. J. Climent, P. Concepción, A. Corma and S. Iborra, ACS Sustainable Chem. Eng., 2019, 7, 6243–6250 CrossRef .
  16. H. Yuan, J.-P. Li, F. Su, Z. Yan, B. T. Kusema, S. Streiff, Y. Huang, M. Pera-Titus and F. Shi, ACS Omega, 2019, 4, 2510–2516 CrossRef CAS PubMed .
  17. V. V. Karve, D. T. Sun, O. Trukhina, S. Yang, E. Oveisi, J. Luterbacher and W. L. Queen, Green Chem., 2020, 22, 368–378 RSC .
  18. A. L. Nuzhdin, M. V. Bukhtiyarova and V. I. Bukhtiyarov, Molecules, 2020, 25, 4771 CrossRef CAS PubMed .
  19. V. G. Chandrashekhar, K. Natte, A. M. Alenad, A. S. Alshammari, C. Kreyenschulte and R. V. Jagadeesh, ChemCatChem, 2021, 14, e202101234 CrossRef .
  20. A. L. Nuzhdin, P. A. Simonov and V. I. Bukhtiyarov, Kinet. Catal., 2021, 62, 507–512 CrossRef CAS .
  21. A. L. Nuzhdin, P. A. Simonov, G. A. Bukhtiyarova, I. V. Eltsov and V. I. Bukhtiyarov, Mol. Catal., 2021, 499, 111297 CrossRef CAS .
  22. Q. Hu, S. Jiang, Y. Wu, H. Xu, G. Li, Y. Zhou and J. Wang, ChemSusChem, 2022, 15, e202200192 CrossRef CAS PubMed .
  23. H. Qi, J. Yang, F. Liu, L. Zhang, J. Yang, X. Liu, L. Li, Y. Su, Y. Liu, R. Hao, A. Wang and T. Zhang, Nat. Commun., 2021, 12, 3295 CrossRef CAS PubMed .
  24. K. I. Galkin, F. A. Kucherov, O. N. Markov, K. S. Egorova, A. V. Posvyatenko and V. P. Ananikov, Molecules, 2017, 22, 2210 CrossRef PubMed .
  25. K. M. R. V. Jagadeesh, A. S. Alshammari, H. Neumann, M.-M. Pohl, J. Radnik and M. Beller, Science, 2017, 358, 326–332 CrossRef PubMed .
  26. D. Rigo, D. Polidoro, A. Perosa and M. Selva, Mol. Catal., 2021, 514, 111838 CrossRef CAS .
  27. S. Hameury, H. Bensalem and K. De Oliveira Vigier, Catalysts, 2022, 12, 1306 CrossRef CAS .
  28. X. Zhuang, J. Liu, S. Zhong and L. Ma, Green Chem., 2022, 24, 271–284 RSC .
  29. X. Li, J. Zhao, B. Sun, C. Wang, X. Zhang and X. Mu, ACS Sustainable Chem. Eng., 2023, 11, 17951–17978 CrossRef CAS .
  30. E. Redina, N. Arkhipova, G. Kapustin, O. Kirichenko, I. Mishin and L. Kustov, ChemCatChem, 2023, 15, e202300294 CrossRef CAS .
  31. Y. Xiao, C. Shen, Z. Xiong, Y. Ding, L. Liu, W. Zhang and Y. A. Wu, Small, 2023, 19, e2302271 CrossRef PubMed .
  32. V. Bressi, F. Minio, A. M. Balu, E. Rodríguez-Castellón, A. Marrocchi, L. Vaccaro, C. Espro, S. M. Osman, R. Luque and T. Chhabra, Sustainable Chem. Pharm., 2024, 37, 101436 CrossRef CAS .
  33. C. Moriana Herraiz, K. S. Arias, M. J. Climent, S. Iborra and A. Corma, Green Chem., 2024, 26, 9118–9131 RSC .
  34. J. Zhang, J. Yang, X. Li, B. Mu, H. Liu, C. Xia, A. Wang and Z. Huang, Green Synth. Catal., 2024, 5, 42–50 CrossRef CAS .
  35. D. Pingen, J. B. Schwaderer, J. Walter, J. Wen, G. Murray, D. Vogt and S. Mecking, ChemCatChem, 2018, 10, 3027–3033 CrossRef CAS .
  36. J. Zhang, J. Yang, X. Li, H. Liu, A. Wang, C. Xia, J. Chen and Z. Huang, ACS Sustainable Chem. Eng., 2022, 10, 5526–5537 CrossRef CAS .
  37. X. Zhuang, J. Liu, Y. Ji, X. Wu, X. Zhang, L. Chen, Q. Zhang and L. Ma, Chem Catal., 2023, 3, 100699 CrossRef CAS .
  38. Y. Xu, J. Zhang, P. Wang, Y. Fan, Y. Jiang, X. Duan, Y. Li and J. Zhang, Chem. Eng. J., 2024, 480, 148175 CrossRef CAS .
  39. G. Xu, Z. Tu, X. Hu, X. Zhang and Y. Wu, Chem. Eng. J., 2024, 481, 148704 CrossRef CAS .
  40. N. Wang, J. Liu, X. Li and L. Ma, Catal. Commun., 2023, 175, 106620 CrossRef CAS .
  41. Y. Wan, P. Ma, H. Lu, J. Zhang, J. Wang, W. Fang, W. Song, Q. Zheng and W. Lai, J. Catal., 2024, 429, 115285 CrossRef CAS .
  42. P. Liu, H. Zhang, Y. Han, J. Zhao and Y. Zhang, Chem. Eng. J., 2023, 476, 146820 CrossRef CAS .
  43. P. Liu, X. Li, H. Zhang, Y. Zhang and J. Zhao, J. Catal., 2024, 429, 115291 CrossRef CAS .
  44. X. Li and S. Nishimura, Catal. Lett., 2022, 154, 237–244 CrossRef .
  45. Q. Hu, H. Xu, Y. Wu, S. Jiang, J. Wang and Y. Zhou, Mater. Chem. Front., 2023, 7, 2266–2276 RSC .
  46. M.-M. Zhu, L. Tao, Q. Zhang, J. Dong, Y.-M. Liu, H.-Y. He and Y. Cao, Green Chem., 2017, 19, 3880–3887 RSC .
  47. W. Jia, H. Liu, Y. Feng, J. Zhang, X. Zhao, Y. Sun, Z. Wei, S. Yang, X. Tang, X. Zeng and L. Lin, J. Cleaner Prod., 2022, 345, 131029 CrossRef CAS .
  48. A. Cukalovic and C. V. Stevens, Green Chem., 2010, 12, 1201–1206 RSC .
  49. J. J. Roylance and K.-S. Choi, Green Chem., 2016, 18, 5412–5417 RSC .
  50. M. Zhang, S. Xu, M. Boubeche, D. Decarolis, Y. Huang, B. Liu, E. K. Gibson, X. Li, Y. Wang, H. Luo, C. R. A. Catlow and K. Yan, Green Chem., 2022, 24, 9570–9578 RSC .
  51. T. Irrgang and R. Kempe, Chem. Rev., 2020, 120, 9583–9674 CrossRef CAS PubMed .
  52. J. He, L. Chen, S. Liu, K. Song, S. Yang and A. Riisager, Green Chem., 2020, 22, 6714–6747 RSC .
  53. D. Pinheiro and M. Nielsen, Catalysts, 2021, 11, 558 CrossRef CAS .
  54. W. J. Liu, X. Zhou, Y. Min, J. W. Huang, J. J. Chen, Y. Wu and H. Q. Yu, Adv. Mater., 2023, 36, 2305924 CrossRef .
  55. F. Valentini, V. Kozell, C. Petrucci, A. Marrocchi, Y. Gu, D. Gelman and L. Vaccaro, Energy Environ. Sci., 2019, 12, 2646–2664 RSC .
  56. A. Boddien, F. Gärtner, C. Federsel, P. Sponholz, D. Mellmann, R. Jackstell, H. Junge and M. Beller, Angew. Chem., Int. Ed., 2011, 50, 6411–6414 CrossRef CAS PubMed .
  57. H. Brunner and W. Leitner, Angew. Chem., Int. Ed., 2003, 27, 1180–1181 CrossRef .
  58. W. Gan, C. Fellay, P. J. Dyson and G. Laurenczy, J. Coord. Chem., 2010, 63, 2685–2694 CrossRef CAS .
  59. N. Gorgas, A. Ilic and K. Kirchner, Monatsh. Chem., 2018, 150, 121–126 CrossRef PubMed .
  60. I. Mellone, N. Gorgas, F. Bertini, M. Peruzzini, K. Kirchner and L. Gonsalvi, Organometallics, 2016, 35, 3344–3349 CrossRef CAS .
  61. Q. Umar and M. Luo, Reactions, 2023, 4, 117–147 CrossRef CAS .
  62. C. Wang, A. Pettman, J. Basca and J. Xiao, Angew. Chem., Int. Ed., 2010, 49, 7548–7552 CrossRef CAS PubMed .
  63. Q. Lei, Y. Wei, D. Talwar, C. Wang, D. Xue and J. Xiao, Chem. – Eur. J., 2013, 19, 4021–4029 CrossRef CAS PubMed .
  64. C. Wang and J. Xiao, Chem. Commun., 2017, 53, 3399–3411 RSC .
  65. Y. Wei, C. Wang, X. Jiang, D. Xue, J. Li and J. Xiao, Chem. Commun., 2013, 49, 5408–5410 RSC .
  66. F. J. King, A. D. Searle and M. W. Urquhart, Org. Process Res. Dev., 2020, 24, 2915–2926 CrossRef CAS .
  67. S. P. Swain, N. Prasad, L. Reddy, G. Subrahmanyam and S. Mohanty, ChemistrySelect, 2021, 6, 1088–1092 CrossRef CAS .
  68. L. V. Romashov and V. P. Ananikov, Org. Biomol. Chem., 2016, 14, 10593–10598 RSC .
  69. Q. Zou, C. Wang, J. Smith, D. Xue and J. Xiao, Chem. – Eur. J., 2015, 21, 9656–9661 CrossRef CAS PubMed .
  70. Y. H. Kang, X. D. Liu, N. Yan, Y. Jiang, X. Q. Liu, L. B. Sun and J. R. Li, J. Am. Chem. Soc., 2016, 138, 6099–6102 CrossRef CAS PubMed .
  71. K. Geng, T. He, R. Liu, S. Dalapati, K. T. Tan, Z. Li, S. Tao, Y. Gong, Q. Jiang and D. Jiang, Chem. Rev., 2020, 120, 8814–8933 CrossRef CAS PubMed .
  72. L. Fakhouri, C. D. Cook, M. H. Al-Huniti, L. M. Console-Bram, D. P. Hurst, M. B. S. Spano, D. J. Nasrallah, M. G. Caron, L. S. Barak, P. H. Reggio, M. E. Abood and M. P. Croatt, Bioorg. Med. Chem., 2017, 25, 4355–4367 CrossRef CAS PubMed .

Footnote

† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4cy00812j
This journal is © The Royal Society of Chemistry 2024