1,3,2-benzodioxaborole catecholborane

Hydroboration, the addition of a boron-hydrogen bond across an unsaturated moiety, was first discovered by H. C. Brown in 1956. Usually, the reaction does not require a catalyst, and the borane reagent, most commonly diborane (B2H6) or a borane adduct (BH3-THF), reacts rapidly at room temperature to afford, after oxidation, the /AMarkovnikov alkene hydration product. However, when the boron of the hydroborating agent is bonded to heteroatoms which lower the electron deficiency, as is the case in catecholborane (1,3,2-benzodioxaborole) 1 (Scheme 1), elevated temperatures are needed for hydroboration to occur.4 5... 

Catecholborane (1,3,2-benzodioxaborole) with a purity of 95% was purchased from Aldrich Chemical Company, Inc. and purified by distillation under nitrogen, bp 58°C (52 mm). For the distillation and handling of air and moisture sensitive compounds, see references 3-5. Catecholborane is a liquid at room temperature, and the neat material is 9.0 H in catecholborane. The preparation of catecholborane from borane and catechol has been reported. ... 

Another secondary borane useful for the conversion of alkenes into alcohols and of alkynes to aldehydes or ketones is catecholborane (1,3,2-benzodioxaborole), which is prepared from catechol and borane in tetrahydrofuran [1201] (equations 600 and 601). 

Catecholborane (1,3,2-Benzodioxaborole), 4,25, 69-70 5, 100-101 6, 33-34, 98. Hydroboration, This process has been reviewed (66 references). Deoxygenation (6, 98). Tosylhydrazones of a, -unsaturated carbonyl compounds are reduced by 1 equiv. of this hydride (1) to methylene derivatives, with migration of the double bond. The reaction is believed to proceed through a diazene intermediate. ... 

Several oxygen- and sulfur-substituted boranes have been reported (125—130). 1,3,2-Benzodioxaborole [274-07-7] (catecholborane, CB) (15) is the one best studied. It is commercially available or can be prepared by the reaction of catechol with borane-THF (57,131), or by other procedures (132). The product is a Hquid existing as a monomer, remarkably stable to disproportionation. No... 

In the hydroboration/oxidation reaction of 2-cyclohexen-l-ol derivatives the regio- as well as the stereoselectivities can be steered in either of two directions by use of different reagents and reaction conditions. Dialkylboranes, e.g., 9-BBN, give mainly tn rs-l,2-diols, whereas with 1,3,2-benzodioxaborole ( catecholborane") in the presence of the rhodium hydrogenation catalyst Rh(PPh3)jCl the trans-1,3-diols become predominant. The cis- 1,2-diols are usually only formed in trace amounts, but the cis-l,3-diols are always produced as byproducts in 10 — 20% yield (D.A. Evans, 1988). 

Acyclic dialkoxyboranes, (RO)2BH, readily disproportionate, 4 but a number of heterocyclic analogs, such as the trimethyldioxaborinane (1), catecholborane (2 1,3,2-benzodioxaborole) and 1,3,2-dithiaboro-... 

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