Pinacolborane Explained

Pinacolborane is the borane with the formula (CH₃)₄C₂O₂BH. Often pinacolborane is abbreviated HBpin.^[1] It features a boron hydride functional group incorporated in a five-membered C₂O₂B ring. Like related boron alkoxides, pinacolborane is monomeric. It is a colorless liquid.^[2] It features a reactive B-H functional group.

Use in organic synthesis

In the presence of catalysts, pinacolborane hydroborates alkenes and, less rapidly, alkynes.^{[3] [4]}

Pinacolborane also affects catalyst-free hydroboration of aldehydes,^[5] ketones,^[6] and carboxylic acids.^[7]

Pinacolborane is used in borylation, a form of C-H activation.^{[8] [9]}

Dehydrogenation of pinacolborane affords dipinacolatodiborane (B₂pin₂):^[10]

2(CH₃)₄C₂O₂BH → (CH₃)₄C₂O₂B-BO₂C₂(CH₃)₄ + H₂

Related compounds

• Catecholborane

References

1. Web site: 4,4,5,5-Tetramethyl-1,3,2-dioxaborolane .
2. Encyclopedia: 10.1002/047084289X.rn00574.pub3. Pinacolborane. Encyclopedia of Reagents for Organic Synthesis. 2017. Ramachandran. P. Veeraraghavan. Chandra. J. Subash. Ros. Abel. Fernández. Rosario. Lassaletta. José M.. Aggarwal. Varinder K.. Blair. Daniel J.. 1–12. 9780470842898.
3. Book: Brown, H.C. . Zaidlewicz, M. . Organic Syntheses Via Boranes, Vol. 2. Aldrich Chemical Co.. Milwaukee, WI. 2001. 978-0-9708441-0-1.
4. Robert J. . Ely. James P. . Morken. 10.15227/orgsyn.088.0342. Stereoselective Nickel-Catalyzed 1,4-Hydroboration of 1,3-Dienes. Organic Syntheses. 88. 342. 2011. free.
5. Stachowiak. Hanna. Kaźmierczak. Joanna. Kuciński. Krzysztof. Hreczycho. Grzegorz. 2018. Catalyst-free and solvent-free hydroboration of aldehydes. Green Chemistry. en. 20. 8. 1738–1742. 10.1039/C8GC00042E. 1463-9262.
6. Wang. Weifan. Luo. Man. Yao. Weiwei. Ma. Mengtao. Pullarkat. Sumod A.. Xu. Li. Leung. Pak-Hing. 2019. Catalyst-free and solvent-free hydroboration of ketones. New Journal of Chemistry. en. 43. 27. 10744–10749. 10.1039/C9NJ02722J. 197130591. 1144-0546.
7. Harinath. Adimulam. Bhattacharjee. Jayeeta. Panda. Tarun K.. 2019. Facile Reduction of carboxylic acids to primary alcohols under catalyst-free and solvent-free conditions. Chemical Communications. en. 55. 10. 1386–1389. 10.1039/C8CC08841A. 30607398. 58570916. 1359-7345.
8. 10.15227/orgsyn.092.0373. 26839440. 4733874. 2015. Amaike. K.. Direct C7 Functionalization of Tryptophan. Synthesis of Methyl (S)-2-((tert-Butoxycarbonyl)amino)-3-(7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-indol-3-yl)propanoate. Organic Syntheses. 92. 373–385. Loach. R. P.. Movassaghi. M..
9. Tatsuo . Ishiyama. Jun. Takagi. Yusuke. Nobuta. Norio Miyaura. Norio. Miyaura. 10.15227/orgsyn.082.0126. Iridium-Catalyzed C-H Borylation of Arenes and Heteroarenes: 1-Chloro-3-Iodo-5-(4,4,5,5-Tetramethyl-1,3,2-Dioxaborolan-2-Yl)Benzene and 2-(4,4,5,5,-Tetramethyl-1,3,2-Dioxaborolan-2-Yl)Indole. Organic Syntheses. 82. 126. 2005. 2115/56319. free.
10. 10.1021/acs.chemrev.6b00193. Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse. 2016. Neeve. Emily C.. Geier. Stephen J.. Mkhalid. Ibraheem A. I.. Westcott. Stephen A.. Marder. Todd B.. Chemical Reviews. 116. 16. 9091–9161. 27434758. free. 1807/78811. free.