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The correct title of this article is 9-Borabicyclo[3.3.1]nonane. The substitution or omission of any brackets is because of technical restrictions.
9-BBN dimer structure.svg
BBN Crystals.jpg
IUPAC name
Other names
Banana borane
3D model (Jmol)
Abbreviations 9-BBN
ECHA InfoCard 100.005.456
EC Number 206-000-9
Molar mass 244.04 g·mol−1
Density 0.894 g/cm3
Melting point 153 to 155 °C (307 to 311 °F; 426 to 428 K)
R-phrases R11 R14/15 R36/37/38
S-phrases S7/9 S16 S33 S7/8 S26 S37/39
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

9-Borabicyclo[3.3.1]nonane or 9-BBN is an organoborane compound. This colourless solid is used in organic chemistry as a hydroboration reagent. The compound exists as a hydride-bridged dimer, which easily cleaves in the presence of reducible substrates.[1] 9-BBN is also known by its nickname 'banana borane'. This is because rather than drawing out the full structure, chemists often simply draw a banana shape with the bridging boron.[2][better source needed]


9-BBN is prepared by the reaction of 1,5-cyclooctadiene and borane usually in ethereal solvents, for example:[3][4]

Synthesis of 9-BBN dimer.png

The compound is commercially available as a solution in tetrahydrofuran and as a solid. 9-BBN is especially useful in Suzuki reactions.[5][6][7]

Its highly regioselective addition on alkenes allows the preparation of terminal alcohols by subsequent oxidative cleavage with H2O2 in aqueous KOH. The steric demand of 9-BBN greatly suppresses the formation of the 2-substituted isomer compared to the use of borane.


  1. ^ Brown, H. C. (1975). Organic Syntheses via Boranes. New York: John Wiley & Sons. ISBN 0-471-11280-1. 
  2. ^ "Molecules with Silly or Unusual Names - page 3". Chm.bris.ac.uk. 2014-05-07. Retrieved 2016-06-01. 
  3. ^ Soderquist, John A.; Brown, Herbert C. (1981). "Simple, remarkably efficient route to high purity, crystalline 9-borabicyclo[3.3.1]nonane (9-BBN) dimer". J. Org. Chem. 46 (22): 4599–4600. doi:10.1021/jo00335a067. 
  4. ^ Soderquist, John A.; Alvin, Negron (1998). "9-Borabicyclo[3.3.1]nonane Dimer". Org. Synth. ; Coll. Vol., 9, p. 95 
  5. ^ Ishiyama, Tatsuo; Miyaura, Norio; Suzuki, Akira. "Palladium(0)-catalyzed reaction of 9-alkyl-9-borabicyclo[3.3.1]nonane with 1-bromo-1-phenylthioethene: 4-(3-cyclohexenyl)-2-phenylthio-1-butene". Org. Synth. ; Coll. Vol., 9, p. 107 
  6. ^ Balog, A.; Meng, D.; Kamenecka, T.; Bertinato, P.; Su, D.-S.; Sorensen, E. J.; Danishefsky, S. J. (1996). "Total Synthesis of (−)-Epothilone A". Angew. Chem. Int. Ed. Engl. 35: 2801. doi:10.1002/anie.199628011. 
  7. ^ Liu, J.; Lotesta, S. D.; Sorensen, E. J. (2011). "A concise synthesis of the molecular framework of pleuromutilin". Chem. Commun. 47: 1500. doi:10.1039/C0CC04077K. PMC 3156455Freely accessible. PMID 21079876. 

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