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Heck-type cross coupling of phenylboronic acid and alkenes and alkynes has been demonstrated. [9] Aryl azides and nitroaromatics can also be generated from phenylboronic acid. [4] Phenylboronic acid can also be regioselectively halodeboronated using aqueous bromine, chlorine, or iodine: [10] PhB(OH) 2 + Br 2 + H 2 O → PhBr + B(OH) 3 + HBr
Boronic acids are used extensively in organic chemistry as chemical building blocks and intermediates predominantly in the Suzuki coupling. A key concept in its chemistry is transmetallation of its organic residue to a transition metal. The compound bortezomib with a boronic acid group is a drug used in chemotherapy.
The Suzuki reaction or Suzuki coupling is an organic reaction that uses a palladium complex catalyst to cross-couple a boronic acid to an organohalide. [1] [2] [3] It was first published in 1979 by Akira Suzuki, and he shared the 2010 Nobel Prize in Chemistry with Richard F. Heck and Ei-ichi Negishi for their contribution to the discovery and development of noble metal catalysis in organic ...
The general outline for the organic synthesis of a CBS catalyst is shown below. The first leg of the reaction sequence starts from the azeotropic dehydration of a boronic acid (1) such as one based on toluene to a boroxine (2). This boroxine reacts with the proline derivative (3d) to form the basic oxazaborolidine CBS catalyst (4).
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 traditional Balz–Schiemann reaction employs HBF 4 and involves isolation of the diazonium salt. Both aspects can be profitably modified. Other counterions have been used in place of tetrafluoroborates, such as hexafluorophosphates (PF 6 −) and hexafluoroantimonates (SbF 6 −) with improved yields for some substrates.
[4] [5] The reaction has since been extended to the synthesis of β-keto esters from the condensation between aldehydes and diazo esters. [6] The general reaction scheme is as follows: General Scheme for Buchner Reaction. The reaction yields two possible carbonyl compounds (I and II) along with an epoxide (III). The ratio of the products is ...
Synthesis of β-arylvinyl halide by microwave-induced Hunsdiecker reaction. For unsaturated compounds, the radical conditions associated with the Hunsdiecker reaction can also induce polymerization instead of decarboxylation. [12]: 468 Consequently, reactions with α,β-unsaturated carboxylic acids typically give low yield. [11]