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The general structure of a boronic acid, where R is a substituent. A boronic acid is an organic compound related to boric acid (B(OH) 3) in which one of the three hydroxyl groups (−OH) is replaced by an alkyl or aryl group (represented by R in the general formula R−B(OH) 2). [1]
Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH) 2 where Ph is the phenyl group C 6 H 5 - and B(OH) 2 is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis.
The reaction is much slower with ketones than aldehydes. [40] For example, in Nicolaou's epothilones synthesis, asymmetric allylboration (with an allylborane derived from chiral alpha-pinene) is the first step in a two-carbon homologation to acetogenin: [41] Trifluoroborate salts are stabler than boronic acids and selectively alkylate aldehydes ...
B(C 6 F 5) 3 forms a strong Lewis adduct with water, [5] which was shown to be a strong Brønsted acid having an acidity comparable to hydrochloric acid (in acetonitrile). [6] In consequence, even traces of moisture are able to deactivate B(C 6 F 5) 3 and remaining catalytic activity might only be due to the Brønsted acidity of the water adduct.
Borinic acid, also known as boronous acid, is an oxyacid of boron with formula H 2 BOH. Borinate is the associated anion of borinic acid with formula H 2 BO −; however, being a Lewis acid, the form in basic solution is H 2 B(OH) − 2. Borinic acid can be formed as the first step in the hydrolysis of diborane: [1] BH 3 + H 2 O → H 2 BOH + H 2
The mechanism of organotrifluoroborate-based Suzuki-Miyaura coupling reactions has recently been investigated in detail. The organotrifluoroborate hydrolyses to the corresponding boronic acid in situ, so a boronic acid can be used in place of an organotrifluoroborate, as long as it is added slowly and carefully. [7] [8]
The reaction of boron trichloride with alcohols was reported in 1931, and was used to prepare dimethoxyboron chloride, B(OCH 3) 2 Cl. [3] Egon Wiberg and Wilhelm Ruschmann used it to prepare tetrahydroxydiboron by first introducing the boron–boron bond by reduction with sodium and then hydrolysing the resulting tetramethoxydiboron, B 2 (OCH 3) 4, to produce what they termed sub-boric acid. [4]
The tert-butyloxycarbonyl protecting group or tert-butoxycarbonyl protecting group [1] (BOC group) is an acid-labile protecting group used in organic synthesis. The BOC group can be added to amines under aqueous conditions using di- tert -butyl dicarbonate in the presence of a base such as sodium hydroxide :