A mechanistic proposal for the protodeboronation of neat boronic acids: boronic acid mediated reaction in the solid state

Abstract

A combined experimental and computational study suggests that a reduction in the entropy of activation in the solid state can lead to the protodeboronation of boronic acids.

Dehydration of ortho‐, meta‐ and para‐Alkoxy Phenylboronic Acids to their Corresponding Boroxines

“…The decomposition of samples 2 , 3 and 3a is in agreement with previous reports on the possible autooxidation process, which can be initiated by the presence of boroxines in the sample . The protodeboronation reaction as a decomposition path should also be taken into account , . The decomposition of samples 2 , 3 and 3a is not observed in nonsealed pans (Figures S3–S5) probably due to the applied inert atmosphere.…”

Protodeboronation of Heteroaromatic, Vinyl, and Cyclopropyl Boronic Acids: pH–Rate Profiles, Autocatalysis, and Disproportionation

“…Given the importance of boronic acids in Suzuki–Miyaura coupling, a process that is frequently conducted in aqueous–organic solvent media, general mechanistic understanding of direct aqueous protodeboronation is surprisingly limited. Moreover, nearly all studies have focused on substituted phenylboronic acids. ,, The most detailed investigation was reported by Kuivila, who measured the protodeboronation kinetics of a series of ArB­(OH) 2 species (Ar = o , m , p -X-C 6 H 4 ; X = MeO, Me, Cl, and F) in aqueous buffers at 90 °C, with initial ArB­(OH) 2 concentrations in the range 3–5 mM. − By analysis of pH–rate profiles (between pH 1.0 and 6.7), two pathways were identified, Scheme . The first was a specific acid-catalyzed process ( k 1 ), shown to proceed via aromatic electrophilic substitution of B by H. The second pathway was found to be base-catalyzed, and proposed to proceed via hydrolysis ( k 2 ) of the boronate anion ([ArB­(OH) 3 ] − ).…”

Trialkylammonium salt degradation: implications for methylation and cross-coupling

“…To understand the potential for long-term safe storage of trimethylanilinium salts, and knowing the potential for reagent storage to cause adverse degradative effects prior to their use in synthesis, 53 our studies began with an investigation of the solidstate stability of arylammonium halides (primarily aniline derivatives). Salts 1a-1c and 2a-15a composed the core structural library employed in our investigations (Fig.…”