Synthesis ofpara-Substituted 3-Formyl Arylboronic Esters

Abstract

S y n t h e s i s o f p a r a -S u b s t i t u t e d 3 -F o r m y l A r y l b o r o n i c E s t e r sAbstract: The synthesis of novel para-substituted amino-and phenoxy-3-formylarylboronic acids is described. These compounds are formed by the hitherto unreported nucleophilic aromatic substitution of fluorine with a range of phenols and amines in the presence of a boronic acid moiety. These reactions proceed in moderate to good yields (37-92%) and provide a useful regioselective synthetic route to trisubstituted arylboronates. These compounds are important both as intermediates in organic synthesis and as end products in their own right.

The Potential of Palladacycles: More Than Just Precatalysts

“…Suzuki couplings used to synthesize the disubstituted biphenylaldehyde led to protodeboronation when using 163 but proceeded smoothly with Pd-(PPh 3 ) 4 (Scheme 122). 304 Similar protodeboronations were also observed, influenced by both the choice of catalyst and the nature of the aryl bromide (Scheme 123). 305 To avoid many of these undesirable decomposition pathways, many of which are due to the high temperatures and long reaction times employed, it might be desirable to develop or employ (i) palladacycles that are active at lower temperatures (e.g.…”

“…Suzuki couplings used to synthesize the disubstituted biphenylaldehyde led to protodeboronation when using 163 but proceeded smoothly with Pd(PPh 3 ) 4 (Scheme ) . Similar protodeboronations were also observed, influenced by both the choice of catalyst and the nature of the aryl bromide (Scheme ) …”

Scalable Synthesis of the Desoxy-biphenomycin B Core

“…The introduction of the boronic acid was accomplished by Schmidt et al via a Grignard protocol. , We considered a low temperature (−75 °C) bromo–lithium exchange pathway more attractive for scale-up since the reaction was dose-controlled and could be monitored more precisely . The price to pay was a higher dilution (0.45 mol/L) in order to keep the reaction mixture agitated at −75 °C.…”

“…The synthesis of the biphenyl derivative 21 was achieved via a Suzuki coupling between bromoaryl 10 and boronic acid 11 . ,, The solvent of choice was a 97:3 mixture of toluene and water from which the desired product conveniently crystallized directly from the reaction mixture.…”

Syntheses of Sterically Hindered Zwitterionic Pyridinium Phenolates as Model Compounds in Nonlinear Optics

“…[19] Finally, boronic acid 16 was converted into ester 7 at room temperature in THF by reaction with pinacol in the presence of molecular sieves. [20] Eventually, the synthesis of boronic ester 7 was performed in 57 % overall yield from bromoanisole 3 and in a 77 % yield from 2,6-di-tert-butylphenol. …”