Diphenylboronic acid

Diphenylboronic acid (Ph2BOH), which is soluble in water, is an effective catalyst for the Mukaiyama aldol reaction in the presence of dodecyl sulfate (SDS) as surfactant. Yields of 93% with syn/anti ratios of 94 6 have been reached according to Eq. (3). The proposed mechanism of this reaction is shown in Scheme 1 [10b]. 

A five-fold increase in sensitivity in the detection of aldopentoses on paper chromatograms has been achieved by using a spray reagent composed of diphenylboronic acid and 2-amino-ethanol prior to spraying with a 4-anisidine phosphate reagent. 

A and n.m.r. study of redistribution phenomena of fluorine and chlorine monofunctional three- and four-co-ordinated boron centres has appeared. and C n.m.r. have been used to study the stereodynamics of enantiomerization in bis(di-isopropylamine)aminoboranes, to study 1,3,2-diazaboracycloalkanes and phenylborane derivatives, and to study three reversible exchange processes in diphenylboronic acid diethanolamine ester. A variety of spectral data (m.s., i.r., and C, and n.m.r.) have been used to investigate the molecular structure of (l-imidazolyl)diorganylboranes. Crystal structures have been published for the following molecules 4-methyl-2-phenyl-(3/f)-l, 3,5,2-oxadiazaboroline, hydrazinium tetraethynylborate... 

Figure 7 The single-crystal X-ray structure of the diphenylboronic acid - fructose complex obtained by Fallon and co-workers from a 2 to 1 ratio ofphenylboronic acid and d-fructose under non-basic conditions and in the absence of Lewis basic components. Atoms marked in red represent oxygen, pink boron and grey carbon. For clarity hydrogen atoms are not displayed. From the structure it can be observed that the O-B-0 bond angles are reduced, in this instance, to 113° from 120°, while the...

Figure 8 The compressed O-B-0 bond angle of the diphenylboronic acid - D-fructose complex" is found to be between the bond angles expected for sp and sp geometry, sp Geometry provides the closest match to the bound complex, meaning that formation of the tetrahedral boronate dial complex reduces ring strain and lowers the energy of the bound species. This results in a shift of the dynamic equilibrium between the neutral boronic acid dial complex 19 atui the boronate anion diol complex 20, causing the observed increase in the value of the acidity constant, Kf.

Deaggregation of the porphyrin-diboronic acid 6 occurred when it complexed with a sugar, particularly D-fhictose, due to increased hydrophilicity. This resulted in a marked increase in absorbance at 400 nm or fluorescence intensity." Complexation of the diphenylboronic acid derivative 7 with mono- and di-saccharides was studied by c.d., resulting in a method for predicting the absolute configuration of saccharides." ... 

Diphensiiure, /. diphenic acid. Diphenyl-arsenchloriir, n. diphenylarseni oua chloride (chlorodiphenylarsine). -borchlorid, n, diphenylboron chloride, -schwarz, n. diphenyl black,... 

Diphenylboron chloride combines with BSD in methylene chloride to give shiny yellow bis(diphenylboryl)diazene (26) in about 30 % yield (62,63) [Eq. (59)]. Thermostable and acid-resistant compound 26 forms the first... 

The combination of SDS and a Bronsted acid was also investigated in aldol reaction using diphenylboronic add (Scheme 3.71). In this reaction, it should be noted that boron enolates were formed in water, and that high syn selectivity of the product was observed. Boron enolates are known to be water-sensitive, but such species can be successfully used in water imder these reaction conditions. 

Ketoximes have been reacted with aliphatic aldehydes and diphenylborinic acid. " a-Hydroxyalkylation at the oxime oxygen is favoured by a bulky substituent in the aldehyde (leading subsequently to a BOCON diphenylboron chelate), while formaldehyde reacts by A-alkylation (giving a COBON chelate). 

Carbalkoxyhorinic acid esters.—Borinic acid vinyl esters. Ethyl acetoacetate in n-pentane added dropwise to diphenylboron chloride in the same solvent 2-ethoxycarbonyl-l-methylvinyl diphenylborinate. Y 99%.—The product is chelated and quite stable. F. e. s. W. Gerrard, M. F. Lappert, and R. Shaffer-man, Soc. 1958, 3648. 

Aminoethanolato-lA,0)diphenylboron, lOCI. Diphenylborinic acid 2-aminoethyl ester. Aminoethyl diphenylborinate. Hydroxydiphenylborane ethanolamine [15614-89-8]... 

Hydroxy-1,1 -azonaphthalene-4-sulfonic acid, see H-00350 (2-Hydroxybenzaldehydato-0,0 ) diphenylboron, H-OOlOO... 

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