Tandem Diboration–Protoboration of Terminal Alkynes: A Practical Route to α-Substituted Alkenyl Boronates

Abstract

A practical method is introduced for the catalytic conversion of terminal alkynes into α-substituted vinyl boronic esters. The process employs catalytic amounts of nanoparticle-supported gold catalysts and catalytic amounts of copper to effect the overall transformation.

Key words

boron - cross-coupling - AuNPs - alkynes - protonation

Publication History

Received: 28 March 2024

Accepted after revision: 18 May 2024

Article published online:
05 June 2024

• References and Notes

• 1a Miyaura N, Yamada K, Suzuki A. Tetrahedron Lett. 1979; 20: 3437
• 1b Miyaura N, Suzuki A. Chem. Rev. 1995; 95: 2457
• 1c Lennox AJ. J, Lloyd-Jones GC. Chem. Soc. Rev. 2014; 43: 412
• 1d Suzuki A. Chem. Commun. 2005; 4759

For review of hydroboration of alkyne, see:
• 2a Beletskaya I, Pelter A. Tetrahedron 1997; 53: 4957
• 2b Barbeyron R, Benedetti E, Cossy J, Vasseur J.-J, Arseniyadis S, Smietana M. Tetrahedron 2014; 70: 8431
• 2c Yoshida H. ACS Catal. 2016; 6: 1799
• 2d Geier SJ, Vogels CM, Melanson JA, Westcott SA. Chem. Soc. Rev. 2022; 51: 8877

Selective examples of transition-metal-catalyzed β-selective hydroboration:
• 3a Tucker CE, Davidson J, Knochel P. J. Org. Chem. 1992; 57: 3482
• 3b Pereira S, Srebnik M. Tetrahedron Lett. 1996; 37: 3283
• 3c Ohmura T, Yamamoto Y, Miyaura N. J. Am. Chem. Soc. 2000; 122: 4990
• 3d Gunanathan C, Hölscher M, Pan F, Leitner W. J. Am. Chem. Soc. 2012; 134: 14349
• 3e Obligacion JV, Neely JM, Yazdani AN, Pappas I, Chirik PJ. J. Am. Chem. Soc. 2015; 137: 5855
• 4 Morrill C, Funk TW, Grubbs RH. Tetrahedron Lett. 2004; 45: 7733
• 5a Kou T, Jun T, Tatsuo I, Norio M. Chem. Lett. 2000; 29: 126
• 5b Takagi J, Takahashi K, Ishiyama T, Miyaura N. J. Am. Chem. Soc. 2002; 124: 8001
• 6 Gao F, Hoveyda AH. J. Am. Chem. Soc. 2010; 132: 10961
• 7a Jang H, Zhugralin AR, Lee Y, Hoveyda AH. J. Am. Chem. Soc. 2011; 133: 7859

For an alternate Cu-catalyzed synthesis of 2-boryl-1-alkenes from propargylic alcohols, see:
• 7b Mao L, Bertermann R, Emmert K, Szabó K, Marder TB. Org. Lett. 2017; 19: 6586
• 8a Lavallo V, Canac Y, Präsang C, Donnadieu B, Bertrand G. Angew. Chem. Int. Ed. 2005; 44: 5705
• 8b Gao Y, Yazdani S, Kendrick IV A, Junor GP, Kang T, Grotjahn DB, Bertrand G, Jazzar R, Engle KM. Angew. Chem. Int. Ed. 2021; 60: 19871

For a recent review on site-selective functionalization of vicinal bis(boronates), see:
• 9a Viso A, Fernández de la Pradilla R, Tortosa M. ACS Catal. 2022; 12: 10603

For selected examples of site-selective functionalization, see:
• 9b Miller SP, Morgan JB, Nepveux FJ, Morken JP. Org. Lett. 2004; 6: 131
• 9c Mlynarski SN, Schuster CH, Morken JP. Nature 2014; 505: 386
• 9d Lee J, Radomkit S, Torker S, del Pozo J, Hoveyda AH. Nat. Chem. 2018; 10: 99
• 9e Blaisdell TP, Caya TC, Zhang L, Sanz-Marco A, Morken JP. J. Am. Chem. Soc. 2014; 136: 9264
• 9f Nóvoa L, Trulli L, Parra A, Tortosa M. Angew. Chem. Int. Ed. 2021; 60: 11763
• 9g Xu N, Kong Z, Wang JZ, Lovinger GJ, Morken JP. J. Am. Chem. Soc. 2022; 144: 17815
• 9h Teresa J, Velado M, Fernández de la Pradilla R, Viso A, Lozano B, Tortosa M. Chem. Sci. 2023; 14: 1575
• 9i Zhang M, Lee PS, Allais C, Singer RA, Morken JP. J. Am. Chem. Soc. 2023; 145: 8308
• 9j Kong Z, Hu W, Morken JP. ACS Catal. 2023; 11522
• 10a Ishiyama T, Matsuda N, Miyaura N, Suzuki A. J. Am. Chem. Soc. 1993; 115: 11018
• 10b Prokopcová H, Ramírez J, Fernández E, Kappe CO. Tetrahedron Lett. 2008; 49: 4831
• 10c Chen Q, Zhao J, Ishikawa Y, Asao N, Yamamoto Y, Jin T. Org. Lett. 2013; 15: 5766
• 11 Zhao F, Jia X, Li P, Zhao J, Zhou Y, Wang J, Liu H. Org. Chem. Front. 2017; 4: 2235
• 12a Lesley G, Nguyen P, Taylor NJ, Marder TB, Scott AJ, Clegg W, Norman NC. Organometallics 1996; 15: 5137
• 12b Iverson CN, Smith MR. Organometallics 1996; 15: 5155
• 12c Cui Q, Musaev DG, Morokuma K. Organometallics 1997; 16: 1355
• 12d Cui Q, Musaev DG, Morokuma K. Organometallics 1998; 17: 1383
• 12e Ali HA, El Aziz Al Quntar A, Goldberg I, Srebnik M. Organometallics 2002; 21: 4533
• 13 Thomas RLl, Souza FE. S, Marder TB. J. Chem. Soc., Dalton Trans. 2001; 1650
• 14a Toshima N, Yonezawa T. New J. Chem. 1998; 22: 1179
• 14b Narayan N, Meiyazhagan A, Vajtai R. Materials 2019; 12: 3602
• 14c Astruc D. Chem. Rev. 2020; 120: 461
• 15 Ishiyama T, Kitano T, Miyaura N. Tetrahedron Lett. 1998; 39: 2357
• 16 Khan A, Asiri AM, Kosa SA, Garcia H, Grirrane A. J. Catal. 2015; 329: 401
• 17 (E)-2,2′-(3-Phenylprop-1-ene-1,2-diyl)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) In a dry box, an oven-dried 2-dram vial was charged with prop-2-yn-1-ylbenzene (122 mg, 1.05 mmol, 1.05 equiv), B₂(pin)₂ (254 mg, 1.00 mmol, 1.00 equiv), and 3% Au/TiO₂ (98 mg, 5.00 μmol, 0.05 equiv). The mixture was dissolved in toluene (1.00 mL). The reaction mixture was sealed with a PTFE-lined closed cap, brought out of the dry box and stirred at 80 °C for 24 h. At the completion of the reaction, the crude mixture was passed through a short pad of Celite using diethyl ether as solvent. The filtrate was concentrated and purified by column chromatography (silica gel, 0–1% ethyl acetate/hexane, stained with KMnO₄) to give the desired product as a white solid (296 mg, 82%). ¹H NMR (500 MHz, CDCl₃): δ = 7.24 (m, 2 H), 7.18–7.13 (m, 3 H), 5.79 (s, 1 H), 3.55 (d, J = 1.9 Hz, 2 H), 1.26 (s, 12 H), 1.19 (s, 12 H). ¹³C NMR (126 MHz, CDCl₃): δ = 139.4, 129.8, 128.3, 126.1, 83.8, 83.5, 45.7, 25.0, 24.9. HRMS (DART): m/z [M + H]⁺ calcd 371.2560; found: 371.2571. The reaction could also be conducted without a dry box using Schlenk techniques.
• 18 Hitosugi S, Tanimoto D, Nakanishi W, Isobe H. Chem. Lett. 2012; 41: 972
• 19a Miura H, Hachiya Y, Nishio H, Fukuta Y, Toyomasu T, Kobayashi K, Masaki Y, Shishido T. ACS Catal. 2021; 11: 758
• 19b Oka N, Yamada T, Sajiki H, Akai S, Ikawa T. Org. Lett. 2022; 24: 3510
• 19c Ito M, Yamazaki H, Ito A, Oda R, Komiya M, Higuchi K, Sugiyama S. Eur. J. Org. Chem. 2023; 26: e202300458
• 20 4,4,5,5-Tetramethyl-2-(3-phenylprop-1-en-2-yl)-1,3,2-dioxaborolane In a dry box, an oven-dried 2-dram vial was charged with (E)-2,2′-(3-phenylprop-1-ene-1,2-diyl)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (74.0 mg, 0.20 mmol, 1.00 equiv) and lithium methoxide (19.0 mg, 0.50 mmol, 2.5 equiv). The mixture was dissolved in a freshly prepared solution of CuI·2LiCl (0.40 M Cu in THF, 1.00 mL). Isopropanol (solvent grade; 15.6 mg, 0.26 mmol, 1.30 equiv) was then added. The reaction mixture was sealed with a PTFE-lined closed cap, brought out of the dry box, and stirred at rt for 16 h. At the completion of the reaction, the crude mixture was passed through a short pad of silica using diethyl ether as solvent. The filtrate was concentrated and purified by column chromatography (silica gel, 0–2% ethyl acetate/hexane, stained with KMnO₄) to give the desired product as a colorless oil (39 mg, 80%). ¹H NMR (500 MHz, CDCl₃): δ = 7.26 (m, 2 H), 7.22–7.14 (m, 3 H), 5.84 (d, J = 3.3 Hz, 1 H), 5.54 (s, 1 H), 3.49 (s, 2 H), 1.22 (s, 12 H). ¹³C NMR (126 MHz, CDCl₃): δ = 140.8, 129.9, 129.3, 128.2, 125.8, 83.6, 41.5, 24.8. HRMS (DART): m/z [M + H]⁺ calcd 245.1707; found: 245.1712.