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Acid fluorides, relative reactivity toward

The main limitations of using organoboronic acids in cross-coupling chemistry are threefold. These compounds are quite reactive towards many nucleophiles and oxidants, which prohibits installation of the boronic acid functional group early in a synthetic sequence. Moreover, purification of boronic acids is often problematic. Finally, since the C—B bond is relatively nonpolar, transmetalation of an organoboron reagent to Pd(ll) will not occur without coordination of an anionic base or a fluoride ion to the boron atom to afford a four-coordinate ate -complex (e.g. 20 shown below). This requirement poses some limitations with respect to transformations of base- or fluoride-sensitive substrates, although these... [Pg.7]

Hardness or softness is a property of a Lewis acid or base that is independent of its strength. An important aspect of electron availability is polarizability, the ease of distortion of the valence electron shell of an atom by an adjacent charge. For example, the valence electrons of iodide are shielded from the nuclear charge by all of the core electrons and thus are capable of being distorted toward a partially positive reactive site much more easily than the valence electrons of fluoride. Polarizability increases going down a column in the periodic table. For our purposes, it is more important to be able to compare the relative hardness of acids and bases several trends are helpful. [Pg.41]


See other pages where Acid fluorides, relative reactivity toward is mentioned: [Pg.216]    [Pg.202]    [Pg.298]    [Pg.8]    [Pg.350]    [Pg.2]    [Pg.20]   


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Acid fluorides

Acids relative

Fluoride reactivation

Reactivity acidity

Reactivity acids

Reactivity relative reactivities

Relative reactivities

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