{{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 that is useful in organic synthesis. This colourless liquid is a derivative of catechol and a 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 (BH<sub>3</sub>) in a cooled solution of 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 (LiBH<sub>4</sub>, NaBH<sub>4</sub>, KBH<sub>4</sub>) with tris(catecholato)bisborane in an ethereal solvent such as diethyl ether.<ref>[https://www.freepatentsonline.com/4739096.html Process for producing catecholborane – Patent 4739096<!-- Bot generated title -->]</ref> In 2001, Herbert Brown and coworkers prepared catecholborane by treatment of tri-''o''-phenylene bis-borate with 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 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, 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 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 reducing agent when converting β-hydroxy ketones to syn 1,3-diols.
Catecholborane oxidatively adds to low valent metal complexes, affording boryl complexes.<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