Facile and Reliable Synthesis of Tetraphenoxyborates and Their Properties

Abstract

Tetraphenoxyborates are reliably prepared in a two-step sequence, exploiting less corrosive reagents like boric acid and the corresponding phenols. The broad scope of this transformation is demonstrated in 22 examples. Several solid-state structures reveal the preferential conformation of the phenoxy moieties allowing cation interaction. Furthermore, a

Sodium Tetraalkoxyborates: Intermediates for the Quantitative Reduction of Aldehydes and Ketones to Alcohols through Ball Milling with NaBH4

“…[18] Phenols and NaBH 4 (2) react to give related tetraaryloxyborates in THF, [19] or as a result of their low hydrolytic sensitivity, by reaction of boric acid with phenols. [20] …”

Unexpected Highly Chemoselective Anodic ortho‐Coupling Reaction of2,4‐Dimethylphenol on Boron‐Doped Diamond Electrodes

“…Because excess of 1 is easily recovered virtually no loss of material occurs, creating a good basis for a continuous preparation of 2. [13] The elaborated protocol for the oxidative coupling process was applied to a series of low-melting phenols. [14] Either no conversion was observed or the substrate was completely destructed.…”

“…4) are produced in significant amounts (Scheme 1). [1] To overcome this lack of selectivity, we developed recently a template-directed electrochemical synthesis: The phenols are converted to tetraphenoxy borate species, [2] which represent superb substrates for the anodic transformation. [3] Although this process can be performed on a large scale and exhibits excellent selectivity for 2, it requires a multi-step sequence, including the isolation of the temScheme 1.…”

ortho‐Selective Phenol‐Coupling Reaction by Anodic Treatment on Boron‐Doped Diamond Electrode Using Fluorinated Alcohols

“…[10] To prevent electrochemical incineration and to avoid by-products only partial conversion of about 30 % is performed. [11] In such cases the electrochemical transformation is very clean. By using these particular conditions 2,4-dimethylphenol is converted to the biphenol (Scheme 1).…”

“…Methyl-substituted phenols are prone to side reactions and 2,4-dimethylphenol in particular results in predominantly polycyclic architectures upon anodic treatment. [6] To circumvent this challenge we developed a boron-based template strategy [7,8] that can be performed on larger scale. [9] A protocol for the conversion of neat phenol (1) on boron-doped diamond (BDD) electrodes was developed in our laboratory.…”