Catecholborane

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

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Synthesis

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.^[1]

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.^[2]

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.^[3]

Reduction of β-hydroxy ketones

Catecholborane may be used as a stereoselective reducing agent when converting β-hydroxy ketones to syn 1,3-diols.^[4]

See also

• Catechol

References

1. ^ http://www.freepatentsonline.com/4739096.html
2. ^ http://pubs.acs.org/cgi-bin/abstract.cgi/oprdfk/2000/4/i06/abs/op000291w.html
3. ^ Janice Gorzynski Smith. Organic Chemistry: Second Ed. 2008. pp 1007
4. ^ http://evans.harvard.edu/pdf/evans135.pdf