Catecholborane

Chembox new
Name = Catecholborane
ImageFile = Catecholborane structure.png IUPACName = Catecholborane
OtherNames = 1,3,2-benzodioxaborole
7,9-dioxa-8λ2-borabicyclo [4.3.0] nona-1,3,5-triene

Section1 = Chembox Identifiers
SMILES = [B] 1OC2=CC=CC=C2O1
CASNo = 274-07-7
RTECS =
Section2 = Chembox Properties
Formula = C₆H₅BO₂
MolarMass = 119.92 g/mol
Appearance = Colorless liquid
Density = 1.125 g/cm³, liquid
Solubility =
MeltingPt = 12 °C
BoilingPt = 50 °C
pKa =
Section3 = Chembox Structure
Dipole =
Section7 = Chembox Hazards
NFPA-H = 1 | NFPA-F = 4 | NFPA-R = 2 | NFPA-O = W
RPhrases = R11, R14, R34
SPhrases = S16, S26, S36/37/39, S43, S45
FlashPt = 2 °C
Section8 = Chembox Related
Function =
OtherFunctn =
OtherCpds =

Catecholborane, or BHcat, is a derivative of catechol and a boron hydride, with the formula C₆H₄O₂BH. It is commonly used in organic syntheses.

ynthesis

Traditionally catecholborane commonly is produced by reacting catechol with borane (BH₃) in a cooled solution of THF. However, this method results in a loss of 2 mole equivalents of the hydride.

Heinrich Noth and Detlef Mannig devised a method that allows a more efficient recovery of the final product, catecholborane, and subsequently a greater yield. Their method involves reacting an alkali-metal boron hydride (LiBH₄, NaBH₄, of KBH₄) with tris(catecholato)bisborane in an ether solvent such as diethyl ether or diethylene glycol. [ [http://www.freepatentsonline.com/4739096.html Process for producing catecholborane - Patent 4739096 ] ]

In 2001 Herbert Brown released an additional procedure for catecholborane synthesis. His method involves reacting tri-"O"-phenylene bis-borate with diborane in a solution of either triglyme or tetraglyme. Brown claimed his method produces 85% yield of 97% pure product, catecholborane. [ [http://pubs.acs.org/cgi-bin/abstract.cgi/oprdfk/2000/4/i06/abs/op000291w.html New Economical, Convenient Procedures for the Synthesis of Catecholborane ] ]

Reactions

Preparation of an organoborane

When catecholborane is reacted with an alkyne, usually a terminal alkyne, through hydroboration a trans vinylborane is formed. This is the precursor to the Suzuki reaction. [Janice Gorzynski Smith. "Organic Chemistry: Second Ed". 2008. pp 1007]

Reduction of β-hydroxy ketones

Catecholborane may be used as a stereoselective reducing agent when converting β-hydroxy ketones to syn 1,3-diols. [http://evans.harvard.edu/pdf/evans135.pdf]

ee also

* Catechol

References