Boron-11 couplings

Scheme 7 Apical boron coupling reactions of 1 -(C6H6)-2,3-(Et)2-1,2,3-FeC2B4H4 and alkynes. Reproduced by permission of the American Chemical Society from Organometallics 2002, 21, 4113.

A commercial assay is performed on an automated analyzer that uses a soluble reagent consisting of dihydroxy-boronate coupled to high molecular weight polyacrylic acid. GHb binds to the boronate. The polyanionic-glycated hemoglobin affinity complex attaches by electro-... 

The magnitude of these quadrupolar interactions for "B in a-Si H,B films provides convincing evidence that most of the "B nuclei ( 90%) are not tetrahedrally coordinated. Even in highly distorted tetrahedral environments, boron coupling constants in borate minerals and boron-containing molecules are always less than — 1 MHz. 

In studies concerned with optimization of the Suzuki cross-coupling of 2-pyridyl nucleophiles, lithium triisopropyl 2-pyridylborates are shown to be the most suitable boron coupling partners (eq 60). The borates are isolated and subjected to coupling with various aryl and hetaryl halides (X = Cl, Br) to give the corresponding azabiaryls. ... 

The most popnlar class of the boronic acid-based sensors utilize an amine gronp proximal to boron coupled to a fluorescence outpnL The Lewis acid-Lewis base interaction between the boronic acid and the tertiary amine has a dual role. Firstly, it enables molecular recognition at nentral pH. Secondly, it can be nsed to signal binding by modnlating the intensity of flnorescence emissions. 

The high-resolution NMR spectrum of diborane(6) has been recorded and details of direct boron-boron coupling were observed. The values are J( B, B)=1.3 Hz, J( B, B)=3.8 0.2 Hz. Coupling constants used for accurately calculating the spectrum are given in Table 2/19 [12]. 

Stable boronate salts 139 and 140, which were developed by Miyaura and coworkers, can be alternatively utilized in cross-coupling reactions with disubsti-tuted bromothiophenes 138 (Scheme 56, Table 34) [353, 354], The one-pot double boronate coupling of 2,4- or 2,3-dibromothiophene 138 proceeds under mild reaction conditions in aqueous solution giving rise to the corresponding products 141 in good to high yields. The application of arylboronic acids instead of the boronate salts results in poorer yields in most of the cases. 

R. Weiss and R. N. Grimes, J. Amer. Chem. Soc., 1978, 100, 1401. Sources of linewidth in boron-11 nuclear magnetic resonance spectra. Scalar relaxation and boron-boron coupling in tetraborane(lO) and pentaborane(9). 

C and the resulting boronate coupled with p-bromo benzonitrile 40 to give to the required aryl acetic acid ethyl ester 32 (Scheme 8). 

Work in the area by direct observation is often severely hindered by boron coupling and quadrupolar broadening effects (e.g.. Figure 17), and indirect measurement via H- X spectroscopy can then be of use. ... 

Allyl boronate i additions T Vinyl boronate / [Pg.368]

The controlled thermal decomposition of dry aromatic diazonium fluoborates to yield an aromatic fluoride, boron trifluoride and nitrogen is known as the Schiemann reaction. Most diazonium fluoborates have definite decomposition temperatures and the rates of decomposition, with few exceptions, are easily controlled. Another procedure for preparing the diazonium fluoborate is to diazotise in the presence of the fluoborate ion. Fluoboric acid may be the only acid present, thus acting as acid and source of fluoborate ion. The insoluble fluoborate separates as it is formed side reactions, such as phenol formation and coupling, are held at a minimum temperature control is not usually critical and the temperature may rise to about 20° without ill effect efficient stirring is, however, necessary since a continuously thickening precipitate is formed as the reaction proceeds. The modified procedure is illustrated by the preparation of -fluoroanisole ... 

D Boronic acid coupling 10 l-(4-Methylphenylsulfonyl)indole- l-Benzyl-3-trifluoromethanesulfonyloxy-l,2,5,6- 92 [10]... 

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