Alpine borane

Source: Wikipedia, the free encyclopedia.
Alpine borane[1]
Skeletal formula of alpine borane
Ball-and-stick model of the alpine borane molecule
Names
IUPAC name
9-(2,6,6-Trimethylbicyclo[3.1.1]hept-3-yl)-9-bora-bicyclo[3.3.1]nonane
Other names
Alpine-Borane; B-Isopinocampheyl-9-borabicyclo[3.3.1]nonane; B-3-Pinanyl-9-borabicyclo[3.3.1]nonane
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.157.575 Edit this at Wikidata
  • InChI=1S/C18H31B/c1-12-16-10-13(18(16,2)3)11-17(12)19-14-6-4-7-15(19)9-5-8-14/h12-17H,4-11H2,1-3H3/t12-,13-,14?,15?,16+,17-/m1/s1 checkY
    Key: VCDGSBJCRYTLNU-AZWGFFAPSA-N checkY
  • InChI=1/C18H31B/c1-12-16-10-13(18(16,2)3)11-17(12)19-14-6-4-7-15(19)9-5-8-14/h12-17H,4-11H2,1-3H3/t12-,13-,14?,15?,16+,17-/m1/s1
    Key: VCDGSBJCRYTLNU-AZWGFFAPBY
  • CC4(C)[C@@H]1C[C@H]4[C@@H](C)[C@@H](C1)B3C2CCCC3CCC2
Properties
C18H31B
Molar mass 258.26 g·mol−1
Appearance Colorless liquid
Density 0.947 g/mL
Boiling point > 55 °C (131 °F; 328 K)
Hazards
GHS labelling:
GHS02: Flammable
Danger
H250
P210, P222, P280, P302+P334, P370+P378, P422
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Alpine borane is the commercial name for an

9-BBN and diisopinocampheylborane
.

Preparation and reactions

This

α-pinene.[2]

This sterically crowded

stereoselectively reduce aldehydes in what is known as the Midland Alpine borane reduction, or simply the Midland reduction.[3]

C8H12B-pinanyl + RCDO → C8H12BOCHDR + (+)-d-pinene

Hydrolysis of the resulting borinic ester affords the alcohol:

C8H12BOCHDR + H2O → C8H12BOH + HOCHDR

It is also effective for the stereoselective reduction of certain acetylenic ketones.[4] The reaction is proposed to involve formation of an adduct by coordination of the carbonyl oxygen to boron. Intramolecular hydride transfer from the pinane substituent to the carbonyl carbon ensues. Many substrates for the Midland reduction have a low steric group such as an alkyne[5] or a nitrile[6] so as to increase selectivity. Stereochemical control comes from coordination of the carbonyl bulky borane, followed by hydride transfer opposite the largest group.[2][7]

See also

References

  1. ^ R-Alpine-Borane and S-Alpine-Borane at Sigma-Aldrich
  2. ^
    doi:10.1021/cr00097a010
    .
  3. doi:10.1002/047084289X.rp173
    . Article Online Posting Date: April 15, 2001
  4. doi:10.15227/orgsyn.063.0057
    .
  5. doi:10.1021/jo00384a057
  6. doi:10.1021/jo00217a053
    .
  7. ^ Li, J. J. (2009). Name Reactions, A Collection of Detailed Mechanisms and Synthetic Applications (4th ed.). New York, New York: Springer. pp. 359–360.
    ISBN 978-3-642-01052-1
    .
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