Bis(pinacolato)diboron
Bis(pinacolato)diboron is a covalent compound containing two boron atoms and two pinacolato ligands. It has the formula [(CH3)4C2O2B]2; the pinacol groups are sometimes abbreviated as "pin", so the structure is sometimes represented as B2pin2. It is a colourless solid that is soluble in organic solvents. It is a commercially available reagent for making pinacol boronic esters for organic synthesis. Unlike some other diboron compounds, B2pin2 is not moisture-sensitive and can be handled in air.[1]
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Names | |
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IUPAC name
4,4,4′,4′,5,5,5′,5′-Octamethyl-2,2′-bi(1,3,2-dioxaborolane) | |
Identifiers | |
3D model (JSmol) |
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Abbreviations | B2pin2 |
ChemSpider | |
ECHA InfoCard | 100.111.245 ![]() |
PubChem CID |
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UNII | |
CompTox Dashboard (EPA) |
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Properties | |
C12H24B2O4 | |
Molar mass | 253.94 g·mol−1 |
Melting point | 137 to 140 °C (279 to 284 °F; 410 to 413 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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Infobox references | |
Preparation and structure
This compound may be prepared by reacting tetrakis(dimethylamino)diboron with pinacol in acidic conditions.[1] The B-B bond length is 1.711(6) Å.[2]
Reactions
The B-B bond adds across alkenes and alkynes to give the 1,2-diborylated alkanes and alkenes. Using various organorhodium or organoiridium catalysts, it can also be installed onto saturated hydrocarbons:[3]
- CH3(CH2)6CH3 + [pinB]2 → pinBH + CH3(CH2)7Bpin
These reactions proceed via boryl complexes.
References
- Tatsuo Ishiyama; Miki Murata; Taka-aki Ahiko & Norio Miyaura (2004). "Bis(pinacolato)diboron". Organic Syntheses.; Collective Volume, 10, p. 115
- C.Kleeberg, A.G.Crawford, A.S.Batsanov, P.Hodgkinson, D.C.Apperley, Man Sing Cheung, Zhenyang Lin, T.B.Marder "Spectroscopic and Structural Characterization of the CyNHC Adduct of B2pin2 in Solution and in the Solid State" J. Org. Chem. 2012, vol. 77, pp. 785. doi:10.1021/jo202127c
- Xinyu Liu "Bis(pinacolato)diboron" Synlett 2003, pp 2442–2443. doi:10.1055/s-2003-43344