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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]
The boron atom of a boronic ester or acid is sp 2 hybridized possessing a vacant p orbital, enabling these groups to act as Lewis acids. The C–B bond of boronic acids and esters are slightly longer than typical C–C single bonds with a range of 1.55-1.59 Å.
The Miyaura borylation has shown to work for: Alkyl halides, [2] aryl halides, [1] [3] [4] aryl halides using tetrahydroxydiboron, [5] aryl halides using bis-boronic acid, [6] aryl triflates, [7] aryl mesylates, [8] vinyl halides, [9] vinyl halides of α,β-unsaturated carbonyl compounds, [10] and vinyl triflates.
Basic heteroaromatic boronic acids (boronic acids that contain a basic nitrogen atom, such as 2-pyridine boronic acid) display additional protodeboronation mechanisms. [4] A key finding shows the speciation of basic heteroaromatic boronic acids to be analogous to that of simple amino acids , with zwitterionic species forming under neutral pH ...
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 ...
Metal templating by Cu(II/III) acts as a Lewis acid to both activate the thiol ester and deliver R 2 (from either boron directly or via an intermediate Cu-R 2 species), which produces the ketone and a Cu-thiolate. A second equivalent of boronic acid is needed to break the copper sulfur bond and liberate copper back into the catalytic cycle.
The boron reagent is converted to boric acid. The reaction was originally described by H.C. Brown in 1957 for the conversion of 1-hexene into 1-hexanol. [3] Hexanol synthesis. Knowing that the group containing the boron will be replaced by a hydroxyl group, it can be seen that the initial hydroboration step determines the regioselectivity.
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: [42]