# Catecholborane

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{{chembox
|Watchedfields = changed
|verifiedrevid = 427312003
|Name = Catecholborane
|ImageFile = Catecholborane structure.png
|ImageFile1 = Catecholborane-3D-spacefill.png
|ImageAlt1 = Catecholborane molecule
|PIN = 2''H''-1,3,2-Benzodioxaborole
|OtherNames = 7,9-dioxa-8λ2-borabicyclo[4.3.0]nona-1,3,5-triene
|Section1={{Chembox Identifiers
|SMILES = [B]1OC2=CC=CC=C2O1
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 10617125
|InChI = 1/C6H5BO2/c1-2-4-6-5(3-1)8-7-9-6/h1-4,7H
|InChIKey = CENMEJUYOOMFFZ-UHFFFAOYAI
|SMILES1 = c1cccc2OBOc12
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/C6H5BO2/c1-2-4-6-5(3-1)8-7-9-6/h1-4,7H
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = CENMEJUYOOMFFZ-UHFFFAOYSA-N
|CASNo_Ref = {{cascite|correct|??}}
|CASNo = 274-07-7
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = UB69382H5J
|PubChem = 6327445
|EC_number = 205-991-5
}}
|Section2={{Chembox Properties
|Formula = C<sub>6</sub>H<sub>5</sub>BO<sub>2</sub>
|MolarMass = 119.92 g/mol
|Appearance = Colorless liquid
|Density = 1.125 g/cm<sup>3</sup>, liquid
|MeltingPtC = 12
|BoilingPtC = 50
|BoilingPt_notes = at 50 mmHg
}}
|Section7={{Chembox Hazards
|NFPA-H = 1 | NFPA-F = 4 | NFPA-R = 2 | NFPA-S = W
|GHSPictograms = {{GHS02}}{{GHS05}}
|GHSSignalWord = Danger
|HPhrases = {{H-phrases|225|314}}
|PPhrases = {{P-phrases|210|233|240|241|242|243|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|321|363|370+378|403+235|405|501}}
|FlashPtC = 2
}}
}}

'''Catecholborane''' (abbreviated HBcat) is an [organoboron compound](/source/organoboron_compound) that is useful in [organic synthesis](/source/organic_synthesis). This colourless liquid is a derivative of [catechol](/source/catechol) and a [borane](/source/borane), having the formula C<sub>6</sub>H<sub>4</sub>O<sub>2</sub>BH.

==Synthesis and structure==
Traditionally catecholborane is produced by treating catechol with [borane](/source/borane) (BH<sub>3</sub>) in a cooled solution of [THF](/source/THF). However, this method results in a loss of 2 mole equivalents of the hydride. Nöth and Männig described the reaction of [alkali-metal boron hydride](/source/Borohydride) (LiBH<sub>4</sub>, NaBH<sub>4</sub>, KBH<sub>4</sub>) with tris(catecholato)bisborane in an ethereal solvent such as [diethyl ether](/source/diethyl_ether).<ref>[https://www.freepatentsonline.com/4739096.html Process for producing catecholborane – Patent 4739096<!-- Bot generated title -->]</ref> In 2001, [Herbert Brown](/source/Herbert_C._Brown) and coworkers prepared catecholborane by treatment of tri-''o''-phenylene bis-borate with [diborane](/source/diborane).<ref>{{cite journal|doi=10.1021/op000291w|title=New Economical, Convenient Procedures for the Synthesis of Catecholborane|year=2000|last1=Kanth|first1=Josyula V. B.|last2=Periasamy|first2=Mariappan|last3=Brown|first3=Herbert C.|journal=Organic Process Research & Development|volume=4|issue=6|pages=550–553}}</ref>

Unlike borane itself or alkylboranes, catechol borane exists as a monomer. This behavior is a consequence of the electronic influence of the aryloxy groups that diminish the Lewis acidity of the boron centre.  [Pinacolborane](/source/Pinacolborane) adopts a similar structure.

==Reactions==
Catecholborane is less reactive in hydroborations than borane-THF or borane-dimethylsulfide.

When catecholborane is treated with a terminal [alkyne](/source/alkyne), a trans vinylborane is formed:
:C<sub>6</sub>H<sub>4</sub>O<sub>2</sub>BH + HC<sub>2</sub>R → C<sub>6</sub>H<sub>4</sub>O<sub>2</sub>B-CHCHR
The product is a precursor to the [Suzuki reaction](/source/Suzuki_reaction) and is the only borane which stops at the alkene instead of reacting further to the alkane. <ref>Janice Gorzynski Smith, ''Organic Chemistry: Second Ed''. 2008. pp 1007</ref><ref>{{OrgSynth|author1-link=Norio Miyaura|author2-link=Akira Suzuki (chemist)|first1=Norio|last1=Miyaura|first2=Akira|last2=Suzuki| year = 1990|title=Palladium-Catalyzed Reaction of 1-Alkenylboronates with Vinylic Halides: (1Z,3E)-1-Phenyl-1,3-octadiene|volume=68|page= 130|doi=10.15227/orgsyn.068.0130}}</ref>

Catecholborane may be used as a [stereoselective](/source/stereoselective) [reducing agent](/source/reducing_agent) when converting β-hydroxy ketones to syn 1,3-diols.

Catecholborane [oxidatively adds](/source/oxidative_addition) to low valent metal complexes, affording [boryl complex](/source/boryl_complex)es.<ref>{{cite journal |doi=10.1021/acs.chemrev.6b00193|title=Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse|year=2016|last1=Neeve|first1=Emily C.|last2=Geier|first2=Stephen J.|last3=Mkhalid|first3=Ibraheem A. I.|last4=Westcott|first4=Stephen A.|last5=Marder|first5=Todd B.|journal=Chemical Reviews|volume=116|issue=16|pages=9091–9161|pmid=27434758|doi-access=free|hdl=1807/78811|hdl-access=free}}</ref>
:C<sub>6</sub>H<sub>4</sub>O<sub>2</sub>BH  +  Pt(PR<sub>3</sub>)<sub>2</sub> →  (C<sub>6</sub>H<sub>4</sub>O<sub>2</sub>B)Pt(PR<sub>3</sub>)<sub>2</sub>H

==References==
<references/>

Category:Benzene derivatives
Category:Organoboron compounds
Category:Boranes

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Adapted from the Wikipedia article [Catecholborane](https://en.wikipedia.org/wiki/Catecholborane) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Catecholborane?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.