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DOI: 10.1055/a-2359-8893
Efficient Flow Synthesis of Glycidyl Ether Using BuSnCl3 as a Mild Lewis Acid
We wish to thank the Japan Society for the Promotion of Science (JSPS) for funding through a Grant-in-Aid for Scientific Research (B) (No. 19H02722) and Scientific Research (C) (No. 24K08433).
Abstract
A ring-opening protocol of epichlorohydrin with 2-ethylhexanol was investigated for the synthesis of the corresponding chlorohydrin ether. BuSnCl3 proved to be an efficient mild Lewis acid catalyst, yielding the product with high selectivity. A scalable flow synthesis was achieved by modifying the flow setup. The flow synthesis of the corresponding glycidyl ether from the chlorohydrin ether was also carried out in an efficient manner by using the basic treatment.
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Epichlorohydrin, as a C3 building block that is widely used in organic synthesis, reacts with carbon, oxygen, nitrogen, and various nucleophiles to give functionalized chlorohydrins, which are readily converted into epoxides by subsequent ring-closing reactions.[1] Glycidyl ethers, which can be synthesized from epichlorohydrin and alcohol nucleophiles, are also a group of compounds commonly used in organic synthesis. They can be used in applications such as epoxy formulations, adhesives, fiber treatment agents, and polymer resin monomers, and they are useful as versatile chemical intermediates.[2] [3] Aliphatic glycidyl ethers 4 are commonly prepared by an addition reaction between an alcohol 1 and epichlorohydrin 2 in the presence of a Lewis acid catalyst (Scheme [1], Step 1),[4] followed by an intramolecular ring-closure reaction of the resulting chlorohydrin ether 3 with a base (Scheme [1], Step 2). In this case, chlorohydrin ether 3, the product of the addition reaction in Step 1, can also act as an alcohol 1 to produce undesired byproduct 5. For example, when boron trifluoride etherate is used to produce aliphatic glycidyl ethers, it is difficult to control the second reaction, resulting in a decrease in selectivity in Step 1. The further adduct 5 is introduced into the ring closure reaction in Step 2, and an epoxy compound 6 is produced, making it difficult to use Cl-free products necessary for electronic materials. Therefore, an important issue in organic synthesis is to develop a synthetic method to obtain chlorohydrin ester 3 with high selectivity.
In this paper, we report on the flow synthesis of glycidyl ethers via the halohydrin synthesis from alcohols and epichlorohydrin, for which we found BuSnCl3 acts as a very mild Lewis acid catalyst to ensure a highly selective reaction that gives the desired chlorohydrins.[5] The present flow protocol has the advantages of efficient micro-mixing and precise temperature control, which would contribute to suppressing undesired side reactions.[6] [7]
The reaction of 2-ethylhexanol (1a) with epichlorohydrin (2) was investigated as a model reaction (Table [1]), in which we tested three liquid-type Lewis acids, BuSnCl3, BF3·OEt2, and SnCl4. A mixture of 1a containing 2 mol% BuSnCl3 and epichlorohydrin (2) was mixed using a micromixer with an internal diameter of 600 μm (MiChS α-600) and fed into a stainless-steel tubular reactor with an internal diameter of 1.0 mm and a length of 2.5 m, which was immersed in an oil bath. A back-pressure regulator was connected to the outlet of the tube. When the reaction of 1a (1.1 equiv) and 2 was carried out at 60 °C with a residence time of 10 min, 75% conversion of 2 was attained with a high product selectivity of 96% for chlorohydrin 3a (entry 1). Reaction at 35 °C required longer residence time (entries 2 and 3). BF3·OEt2 and SnCl4 caused higher conversion but with lower selectivity (entries 4 and 5).
a For entries 1–6: A micromixer with 600 μm i.d. was used. For entries 7–10: A micromixer having 200 μm i.d. was used.
b Determined by GC analysis.
These results led us to focus on the conditions using the BuSnCl3 catalyst. The conversion of 2 was increased to 92% with complete selectivity for 3a when the reaction was carried out with an increased amount of 1a (1.5 equiv) (entry 6). The channel size of the micromixers did not affect the results (entry 7). Consequently, we were pleased to find that full conversion of 2 was achieved without loss of selectivity simply with higher catalyst loading (5 mol%) (entry 8). Full conversion was also achieved with 1.2 equivalent of 1a at a higher temperature (120 °C) and shorter residence time (5 min) (entry 9).
The large-scale synthesis of 3a was then investigated using a flow system consisting of two diaphragm pumps, a T-shaped mixer (2 mm i.d.), and a tubular reactor 4.35 mm i.d. and 16.5 m length (internal volume: 245 mL), for which we investigated the reaction with 2 mol% BuSnCl3. After several experiments, we found that the reaction at 120 °C gave 100% conversion with 93% selectivity of 3a (Scheme [2]). Under these conditions, 330 g of 3a could be synthesized in 1 hour.
We also investigated the batch reaction of 1a (120 g, 0.92 mol) using BuSnCl3 in a 300 mL separable flask for comparison (Scheme [3]). The reaction was carried out at 40 °C to suppress the formation of the undesired by-products. The mixture of BuSnCl3 and 2 was added dropwise over 3 h while cooling to keep the reaction temperature constant, and the mixture was stirred for an additional 2 h. As a result, 194 g of 3a was obtained (100% conversion, 95% selectivity) in a total of 5 hours. These results are comparable to those of the flow reaction, but in terms of space-time yield, the productivity of flow synthesis is estimated to be more than 8 times higher.
Diols are challenging in terms of the increased number of possible side reactions. We applied the flow protocol using BuSnCl3 as the catalyst to the reaction of 1,6-hexanediol (1b) with 2 (Scheme [4]). When the reaction with 5 mol% BuSnCl3 was carried out using the flow reactor system at 60 °C with a residence time of 30 min, the desired 3b was obtained in 73% selectivity, which was improved compared with 62% selectivity of the batch reaction carried out under controlled conditions.
The ring closure of chlorohydrin 3a was then studied in a flow system. When 3a was mixed with 7.7 M NaOH aq. and the reaction was carried out at 90 °C with a residence time of 90 min, the desired glycidyl ether 4a was obtained in 95% yield (Scheme [5]).
Finally, we investigated the one-flow synthesis of glycidyl ether 4a by connecting two flow reactors in series (Scheme [6]). After the reaction of 1a and 2 under the conditions given in Table [1] (entry 7), the mixture was mixed with NaOH aq. using a mixer with a 600 μm i.d. The reaction mixture was passed through a stainless-steel tube (2 mm i.d. and 11.5 m length) immersed in an oil bath heated at 90 °C with 90 min residence time. As a result, an 84% yield of the desired glycidyl ether 4a was obtained.
In summary, we have demonstrated that the flow protocol for the ring-opening of epichlorohydrin (2) by 2-ethylhexanol (1a) is suitable for the synthesis of chlorohydrin 3a. BuSnCl3 was found to be an efficient Lewis acid catalyst that afforded chlorohydrin 3a with high selectivity. Scalable flow synthesis of 3a was achieved by modification of the flow setup for scaling up. The flow synthesis of glycidyl ether 4a from 3a was also carried out successfully using a basic treatment. One-flow synthesis of 4a was successfully carried out using two serially connected flow reactors. We are now investigating the large-scale one-flow synthesis of glycidyl ether 4.
1H NMR spectra were recorded with a JEOL JNM-ECS400 (400 MHz) spectrometer and referenced to the solvent peak at 7.26 ppm. 13C NMR spectra were recorded with a JEOL JNM-ECS 400 (100 MHz) spectrometer and referenced to the solvent peak at 77.00 ppm. Splitting patterns are indicated as: br: broad, s: singlet, d: doublet, t: triplet, m: multiplet. GC analysis was performed with a SHIMADZU GC-2014 gas chromatography equipped with a flame-ionization detector using a fused capillary column (J&W DB-1; ID: 0.32 mm, length: 30 m, Film: 1 μm). Infrared (IR) spectra were measured with a JASCO FT/IR-4100 spectrometer and are reported as wavenumber (cm–1). High-resolution mass spectroscopy (HRMS) was recorded with a JOEL AccuTOF GCx. The products 3a, 3b, and 4a were purified by flash chromatography on silica gel (Kanto Chem. Co. Silica Gel 60N; spherical, neutral, 40–50 μm).
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Flow Synthesis of 1-Chloro-3-((2-ethylhexyl)oxy)propan-2-ol (3a); Typical Procedure
A mixture of 2-ethylhexanol (1a, 60 mmol, 7.8 g) and BuSnCl3 (0.8 mmol, 224 mg) was placed in a 10 mL gas-tight syringe, and epichlorohydrin (2, 40 mmol, 3.68 g) was placed in a 5 mL gas-tight syringe. These were pumped by syringe pumps with a flow rate of 0.15 mL/min and 0.05 mL/min, respectively. They were mixed in a 200 μm i.d. mixer and the resulting mixture was fed into a 1.0 mm i.d. and 2.5 m long stainless-steel tubular reactor (internal volume: 1.96 mL), which was immersed in an oil bath heated to 60 °C. A back-pressure regulator was connected to the tubular reactor. The reaction mixture eluted from the reactor was discarded for 20 min, and the following reaction mixture was collected for 10 min. The reaction mixture was subjected to GC analysis. The conversion of 2 and the selectivity of 3a were found to be 96% and 99%, respectively. The product 3a was purified by silica gel column chromatography (hexane/EtOAc, 95:5) (93% isolated yield, 1.10 g).
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Scalable Flow Synthesis of 1-Chloro-3-((2-ethylhexyl)oxy)propan-2-ol (3a)
Epichlorohydrin (2, 4 mol, 370 g) and a mixture of 2-ethylhexanol (1a, 6 mol, 780 g) and BuSnCl3 (0.08 mol, 22.4 g) were placed in containers. These were pumped by two diaphragm pumps with a flow rate of 2.0 mL/min and 6.15 mL/min, respectively. They were mixed in a 2 mm i.d. mixer and the resulting mixture was fed into a 4.35 mm i.d., 16.5 m long stainless-steel tubular reactor (internal volume: 245 mL) immersed in an oil bath heated to 120 °C. The reaction mixture eluted from the reactor was discarded for 1 h, and the following reaction mixture was collected for 30 min. The reaction mixture was subjected to GC analysis. The conversion of 2 and the selectivity of 3a were found to be 100% and 93%, respectively.
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Flow Synthesis of 3,3′-(Hexane-1,6-diylbis(oxy))bis(1-chloropropan-2-ol) (3b)
A mixture of 1,6-hexanediol (1b, 40 mmol, 4.7 g) and BuSnCl3 (5 mmol, 1.4 g) was placed in a 10 mL gas-tight syringe and epichlorohydrin (2, 100 mmol, 9.2 g) was placed in another 10 mL gas-tight syringe. These were pumped by syringe pumps with a flow rate of 0.027 mL/min and 0.038 mL/min, respectively. They were mixed in a 600 μm i.d. mixer and the resulting mixture was fed into a 1.0 mm i.d. and 2.5 m long stainless-steel tubular reactor (internal volume: 1.96 mL) immersed in an oil bath heated to 60 °C. The reaction mixture was discarded for 20 min, and the following reaction mixture was collected for 10 min. The reaction mixture was subjected to GC analysis. The conversion of 1b and the selectivity of 3b were found to be 100% and 73%, respectively. The product 3b was purified by silica gel column chromatography (hexane/EtOAc, 90:10) (69% isolated yield, 469.0 g).
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Flow Synthesis of 2-(((2-Ethylhexyl)oxy)methyl)oxirane (4a)
Chlorohydrin 3a (100 mmol, 22.2 g) and NaOH aq. (7.7 M) were placed in 25 mL gas-tight syringes. These were pumped by syringe pumps with a flow rate of 0.087 mL/min each. They were mixed in a 600 μm i.d. mixer and the resulting mixture was fed into a 1.0 mm i.d. and 20 m long stainless-steel tubular reactor (internal volume: 15.7 mL) immersed in an oil bath heated to 90 °C. The reaction mixture was discarded for 20 min, and the following reaction mixture was collected for 20 min. The product was extracted with Et2O and dried over MgSO4. After evaporation, the residue was purified by silica gel column chromatography (hexane/EtOAc, 90:10) to give the product 4a (95% isolated yield) as a colorless liquid.
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One-Flow Synthesis of 2-(((2-Ethylhexyl)oxy)methyl)oxirane (4a)
A mixture of 2-ethylhexanol (1a, 600 mmol, 78.0 g) and BuSnCl3 (8 mmol, 2.24 g) was placed in a 100 mL gas-tight syringe, and epichlorohydrin (2, 400 mmol, 36.8 g) was placed in a 50 mL gas-tight syringe. These were pumped by syringe pumps with a flow rate of 0.15 mL/min and 0.05 mL/min, respectively. They were mixed in a 200 μm i.d. mixer, and the resulting mixture was fed into a 1.0 mm i.d. and 2.5 m long stainless-steel tubular reactor (internal volume: 1.96 mL), which was immersed in an oil bath heated to 60 °C. NaOH aq. (7.7 M) was placed in a 50 mL gas-tight syringe and mixed with the first reaction mixture using a mixer having 600 μm i.d. The biphasic mixture was then passed through a stainless-steel tube (2 mm i.d. and 11.5 m length) immersed in an oil bath heated at 90 °C with 90 min residence time. A back-pressure regulator was connected to the second tubular reactor. The reaction mixture eluted from the reactor was discarded for 20 min, and the following reaction mixture was collected for 10 min. The mixture was extracted with Et2O (2 × 10 mL) and the organic layer was dried over MgSO4. The product 3a was purified by silica gel column chromatography (hexane/EtOAc, 95:5) (84% isolated yield, 995 mg).
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1-Chloro-3-((2-ethylhexyl)oxy)propan-2-ol (3a)
Obtained as a 50:50 mixture of diastereomers (1.10 g); colorless oil.
1H NMR (CDCl3, 400 MHz): δ = 0.80–0.95 (m, 6 H), 1.20–1.40 (m, 8 H), 1.43–1.55 (m, 1 H), 2.53–2.67 (m, 1 H), 3.30–3.40 (m, 2 H), 4.45–3.65 (m, 4 H), 3.90–4.00 (m, 1 H).
13C NMR (CDCl3, 100 MHz): δ = 10.98, 14.04, 23.01, 23.75, 29.00, 30.43, 45.97, 40.21, 71.31, 71.39, 74.34.
IR (neat): 3850, 2945, 2900, 2783, 1440 cm–1.
HRMS (ESI): m/z [M + Na]+ calcd. for C11H23ClO2Na: 245.1284; found: 245.1264.
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3,3′-(Hexane-1,6-diylbis(oxy))bis(1-chloropropan-2-ol) (3b)
Obtained as 50:50 mixture of diastereomers (460.0 mg); colorless oil.
1H NMR (CDCl3, 400 MHz): δ = 1.30–1.40 (m, 4 H), 1.53–1.64 (m, 4 H), 1.60–1.80 (m, 2 H), 3.40–3.45 (m, 8 H), 3.55–3.65 (m, 4 H), 3.90–4.00 (m, 2 H).
13C NMR (CDCl3, 100 MHz): δ = 25.84, 29.32, 45.89, 70.20, 71.29, 71.52.
IR (neat): 3848, 2948, 2904, 2785, 1440 cm–1.
HRMS (ESI): m/z [M + Na]+ calcd. for C12H24Cl2O4Na: 325.0949; found: 325.0932.
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2-(((2-Ethylhexyl)oxy)methyl)oxirane (4a)
Obtained as a 50:50 mixture of diastereomers; colorless oil.
This product was compared to a commercially available authentic sample.
1H NMR (CDCl3, 400 MHz): δ = 0.85–0.92 (m, 6 H), 1.20–1.58 (m, 9 H), 2.58–2.62 (m, 1 H), 2.76–2.82 (m, 1 H), 3.30–3.42 (m, 3 H), 3.67–3.72 (m, 1 H).
13C NMR (CDCl3, 100 MHz): δ = 11.03, 14.11, 23.07, 29.07, 30.46, 39.66, 44.29, 50.99, 71.62, 74.47, 77.21.
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Conflict of Interest
The authors declare no conflict of interest.
Supporting Information
- Supporting information for this article is available online at https://doi-org.accesdistant.sorbonne-universite.fr/10.1055/a-2359-8893.
- Supporting Information
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References
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- 5e Chen X, McCarthy SP, Gross RA. Macromolecules 1997; 30: 3470
- 5f Kricheldorf HR, Mahler A. Polymer 1996; 37: 4383
- 5g Marton D, Slaviero P, Tagliavini G. Tetrahedron 1989; 45: 7099
- 6a Fukuyama T, Totoki T, Ryu I. Green Chem. 2014; 16: 2042
- 6b Gutmann B, Cantillo D, Kappe CO. Angew. Chem. Int. Ed. 2015; 54: 6688
- 6c Kobayashi S. Chem. Asian J. 2016; 11: 425
- 6d Marcus M, Moody TS, Smyth M, Wharry S. Org. Process Res. Dev. 2020; 24: 1802
- 6e Fukuyama T, Kasakado T, Hyodo M, Ryu I. Photochem. Photobiol. Sci. 2022; 21: 761
- 6f Buglioni L, Raymenants F, Slattery A, Zondag SD. A, Noël T. Chem. Rev. 2022; 122: 2752
- 6g Rodriguez-Zubiri M, Felpin F.-X. Org. Process Res. Dev. 2022; 26: 1766
- 6h Lin G, Qiu H. Chem. Eur. J. 2022; 28: e202200069
- 6i Del Vecchio A, Smallman HR, Morvan J, McBride T, Browne DL, Mauduit M. Angew. Chem. Int. Ed. 2022; 61: e202209564
- 6j Kanya N, Zsigmond TS, Hergert T, Lovei K, Dorman G, Kalman F, Darvas F. Org. Process Res. Dev. 2024; 28: 1288
- 6k Hayes HL. D, Mallia CJ. Org. Process Res. Dev. 2024; 28: 1327
- 6l Laporte AA. H, Masson TM, Zondag SD. A, Noël T. Angew. Chem. Int. Ed. 2024; 6: e202316108
- 6m Fukuyama T, Dakegata A, Ryu I. ARKIVOC 2024; (ii): 202312077
- 7a Watanabe H, Takemoto M, Adachi K, Okuda Y, Dakegata A, Fukuyama T, Ryu I, Wakamatsu K, Orita A. Chem. Lett. 2020; 49: 409
- 7b Kasakado T, Hyodo M, Furuta A, Kamardine A, Ryu I, Fukuyama T. J. Chin. Chem. Soc. 2020; 67: 2253
- 7c Kasakado T, Hirobe Y, Furuta A, Hyodo M, Fukuyama T, Ryu I. Molecules 2021; 26 Article No. 5845
- 7d Hyodo M, Iwano H, Kasakado T, Fukuyama T, Ryu I. Micromachines 2021; 12: 1307
- 7e Kasakado T, Fukuyama T, Nakagawa T, Taguchi S, Ryu I. Beilstein J. Org. Chem. 2022; 18: 152
- 7f Takabayashi R, Feser S, Yonehara H, Ryu I, Fukuyama T. Polym. Chem. 2023; 14: 4515
- 7g Shih Y.-L, Wu Y.-K, Hyodo M, Ryu I. J. Org. Chem. 2023; 88: 6548
For selected reviews, see:
For selected examples, see:
For selected reports on BuSnCl3-catalyzed reactions, see:
For selected reviews, see:
For our recent reports, see:
Corresponding Author
Publication History
Received: 13 April 2024
Accepted after revision: 03 July 2024
Accepted Manuscript online:
03 July 2024
Article published online:
24 July 2024
© 2024. Thieme. All rights reserved
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References
- 1a Singh GS, Mollet K, D’hooghe M, De Kimpe N. Chem. Rev. 2013; 113: 1441
- 1b Huber JE, Raushel J. In Encyclopedia of Reagents for Organic Synthesis [Online]. Epichlorohydrin. 2011
- 2a Matthes R, Frey H. Biomacromolecules 2022; 23: 2219
- 2b Matykiewicz D, Skorczewska K. Materials 2022; 15: 4824
- 2c Baek J, Kim M, Park Y, Kim B.-S. Macromol. Biosci. 2021; 21: 2100251
- 2d Caillol S, Boutevin B, Auvergne R. Polymer 2021; 223: 123663
- 2e Thomas A, Mueller SS, Frey H. Biomacromolecules 2014; 15: 1935
- 2f Urata K, Takaishi N. J. Am. Oil Chem. Soc. 1996; 73: 819
- 2g Urata K, Takahashi N. J. Am. Oil Chem. Soc. 1994; 71: 1027
- 3a Malburet S, Bertrand H, Richard C, Lacabanne C, Dantras E, Graillot A. RSC Adv. 2023; 13: 15099
- 3b Luo H, Yin Y, Wang Y, Li Q, Tang A, Liu Y. Int. J. Adhes. Adhes. 2022; 114: 103026
- 3c Luo J, Luo J, Zhang J, Bai Y, Gao Q, Li J, Li L. Polymers 2016; 8: 346
- 3d Morita Y. J. Appl. Polym. Sci. 2005; 97: 1395
- 4a Shi X.-L, Sun B, Hu Q, Chen Y, Duan P. Green Chem. 2019; 21: 3573
- 4b Moghadam M, Tangestaninejad S, Mirkhani V, Shaibani R. Tetrahedron 2004; 60: 6105
- 4c Tamura R, Fujimoto D, Lepp Z, Misaki K, Miura H, Takahasi H, Ushio T, Nakai T, Hirotsu K. J. Am. Chem. Soc. 2002; 124: 13139
- 4d Pederson RL, Liu KK.-C, Rutan JF, Chen L, Wong C.-H. J. Org. Chem. 1990; 55: 4897
- 4e Otera J, Niibo Y, Tsutsumi N, Nozaki H. J. Org. Chem. 1988; 53: 275
- 4f Nakatsuji Y, Nakamura T, Okahara M, Dishong DM, Gokel GW. J. Org. Chem. 1983; 48: 1237
- 4g Dishong DM, Diamond CJ, Cinoman MI, Gokel GW. J. Am. Chem. Soc. 1983; 105: 586
- 5a Funfuenha W, Punyodom W, Meepowpan P, Limwanich W. Polym. Bull. 2024; 81: 475
- 5b da Silva EP. S, Meneghetti SM. P. Mol. Catal. 2022; 528: 112499
- 5c da Silva DS, Altino FM. R. S, Bortoluzzi JH, Meneghetti SM. P. Mol. Catal. 2020; 494: 111130
- 5d Iwasaki S, Maki T, Onomura O, Nakashima W, Matsumura Y. J. Org. Chem. 2000; 65: 996
- 5e Chen X, McCarthy SP, Gross RA. Macromolecules 1997; 30: 3470
- 5f Kricheldorf HR, Mahler A. Polymer 1996; 37: 4383
- 5g Marton D, Slaviero P, Tagliavini G. Tetrahedron 1989; 45: 7099
- 6a Fukuyama T, Totoki T, Ryu I. Green Chem. 2014; 16: 2042
- 6b Gutmann B, Cantillo D, Kappe CO. Angew. Chem. Int. Ed. 2015; 54: 6688
- 6c Kobayashi S. Chem. Asian J. 2016; 11: 425
- 6d Marcus M, Moody TS, Smyth M, Wharry S. Org. Process Res. Dev. 2020; 24: 1802
- 6e Fukuyama T, Kasakado T, Hyodo M, Ryu I. Photochem. Photobiol. Sci. 2022; 21: 761
- 6f Buglioni L, Raymenants F, Slattery A, Zondag SD. A, Noël T. Chem. Rev. 2022; 122: 2752
- 6g Rodriguez-Zubiri M, Felpin F.-X. Org. Process Res. Dev. 2022; 26: 1766
- 6h Lin G, Qiu H. Chem. Eur. J. 2022; 28: e202200069
- 6i Del Vecchio A, Smallman HR, Morvan J, McBride T, Browne DL, Mauduit M. Angew. Chem. Int. Ed. 2022; 61: e202209564
- 6j Kanya N, Zsigmond TS, Hergert T, Lovei K, Dorman G, Kalman F, Darvas F. Org. Process Res. Dev. 2024; 28: 1288
- 6k Hayes HL. D, Mallia CJ. Org. Process Res. Dev. 2024; 28: 1327
- 6l Laporte AA. H, Masson TM, Zondag SD. A, Noël T. Angew. Chem. Int. Ed. 2024; 6: e202316108
- 6m Fukuyama T, Dakegata A, Ryu I. ARKIVOC 2024; (ii): 202312077
- 7a Watanabe H, Takemoto M, Adachi K, Okuda Y, Dakegata A, Fukuyama T, Ryu I, Wakamatsu K, Orita A. Chem. Lett. 2020; 49: 409
- 7b Kasakado T, Hyodo M, Furuta A, Kamardine A, Ryu I, Fukuyama T. J. Chin. Chem. Soc. 2020; 67: 2253
- 7c Kasakado T, Hirobe Y, Furuta A, Hyodo M, Fukuyama T, Ryu I. Molecules 2021; 26 Article No. 5845
- 7d Hyodo M, Iwano H, Kasakado T, Fukuyama T, Ryu I. Micromachines 2021; 12: 1307
- 7e Kasakado T, Fukuyama T, Nakagawa T, Taguchi S, Ryu I. Beilstein J. Org. Chem. 2022; 18: 152
- 7f Takabayashi R, Feser S, Yonehara H, Ryu I, Fukuyama T. Polym. Chem. 2023; 14: 4515
- 7g Shih Y.-L, Wu Y.-K, Hyodo M, Ryu I. J. Org. Chem. 2023; 88: 6548
For selected reviews, see:
For selected examples, see:
For selected reports on BuSnCl3-catalyzed reactions, see:
For selected reviews, see:
For our recent reports, see:
