Diboronic acid

Polymerization by G—G Goupling. An aromatic carbon—carbon coupling reaction has been employed for the synthesis of rigid rod-like polyimides from imide-containing dibromo compounds and aromatic diboronic acids ia the presence of palladium catalyst, Pd[P(CgH )2]4 (79,80). 

Porphyrin-based diboronic acids as artificial receptors for saccharides 98YGK831. 

In a classical multi-step route the critical point is to conduct (he ring closure quantitatively and regioseleclively. In the synthesis of I.PPP, the precursor polymer 13 is initially prepared in an aryl-aryl coupling from an aromatic diboronic acid and an aromatic dibromoketone. 

Finally, a huge number of different boronic and diboronic acids has been designed with the aim to use them as molecular receptors for saccharide... 

Scheme 1. Formation of a macrocyclic complex between a diboronic acid and a saccharide...

Compounds 167-171 outlined in Fig. 43 form another series of diboronic acids that form complexes with mono- and disaccharides. In these cases the asymmetrical immobilization of chromophoric functional groups, e.g., aromatic rings in 167-170 or Fe -complexation with the related boronate 171, can be analyzed by circular dichroism measurements [256-262]. 

Fig. 43. Compounds 167-171 form a series of diboronic acids for the complexation of saccharides with functional groups that permit analysis by circular dichroism measurements...

Poly(dioxaboralane)s (82) (Fig. 51) with controllable molecular weights were reported to be readily obtained through the condensation reaction between 9,9-dihexylflourene-2,7- diboronic acid and pentaerythritol in toluene with an associated azeotropic removal of water. The molecular weights of the resulting polymers, which ranged between 10,000 and 76,900, were found to depend on the processing conditions of the polymers.117... 

Figure 51 Poly(dioxaboralane)s (82) obtained through the condensation reaction between 9,9-dihexylflourene-2,7-diboronic acid and pentaerythritol in toluene. (Adapted from ref. 117.)...

Yang W, Fan H, Gao X et al (2004) The first fluorescent diboronic acid sensor specific for hepatocellular carcinoma cells expressing sialyl Lewis X. Chem Biol 11 439 148... 

Many other PF copolymers, which do not contain a particularly electron-active moiety, but nevertheless, can improve the performance of the material in PLED have been synthesized. The Huang group [364,365] at Institute of Materials Research and Engineering (IMRE, Singapore) synthesized deep-blue copolymer 272 by Suzuki copolymerization of fluorene-diboronic acid with dibromobenzene. The emission band of 272 has a peak at 420 nm and a well-defined vibronic feature at 448 nm with a fwhm of 69 nm, and virtually no green emission,... 

A very efficient green-emitting fluorene copolymer 304 was synthesized by Shim and coworkers [390] via Suzuki coupling of dibromothieno[3,2-b]thiophene with dialkylfluorene-diboronic acid [390]. The authors compared the EL properties of this copolymer with PFO homopolymer 196 and PFO-bithiophene copolymer 295. Both the absorption and emission spectra of 304 are red-shifted compared with PFO 196 but slightly blue-shifted compared to bithiophene-based copolymer 295. PLEDs fabricated in the configuration ITO/ PEDOT/304/LiF/Al showed a pure green emission (CIE . v 0.29, r 0.63) close to the... 

Mikami, M. Shinkai, S. Synthesis of helical polymers by polycondensation of diboronic acid and chiral tetrols. Chem. Lett. 1995, 603-604. 

A recent example of diasteromeric amplification with achiral guests and a racemic library can be seen in the work of Iwasawa and coworkers. The library members consisted of a racemic polyol and l,4-benzenedi(boronic acid) [2], When these components were mixed in an equimolar ratio in methanol, a precipitate formed, which was insoluble in other organic solvents and thought to be a polymeric boronate. However, when the library members were mixed in the presence of toluene or benzene, a precipitate again formed, but it was soluble in several (nonprotic) organic solvents where boronic ester exchange is slow. With toluene a [2 2] complex of the polyol and diboronic acid formed, as evidenced by NMR and FAB-MS data. X-ray crystallography confirmed that a cyclic structure formed with... 

The Stille coupling was also employed successfully to prepare covalently bound DNA base-pairs. 1,4-, and l,3-bis(stannyl)benzenes were used to connect purine units covalently through a phenylene linker. The reactions gave the desired products in mediocre yield, along the by-products of destannylation and mono-coupling (8.21.), The extension of the procedure to benzene-1,4-diboronic acid met with limited success.29... 

Metalated ferrocenes have served as valuable intermediates for the synthesis of a number of other derivatives. Treatment of lithiated ferrocenes with tributyl borate followed by hydrolysis leads to ferroceneboronic acid (XXXIII) as well as the diboronic acid (73). Ferroceneboronic acid, like benzeneboronic acid, is readily cleaved by cupric bromide or cupric chloride to form the corresponding halo derivatives (XXXIV). Ferrocene-l,l -diboronic acid reacts in the same manner, and either one or two carbon-boron bonds can be cleaved. Further reactions of this type have led to a variety of mixed dihaloferrocenes (73, 75). 

Todd, M. H. Balasubramanian, S. Abell, C. Studies on the Synthesis, Characterisation and Reactivity of Aromatic Diboronic Acids, Tetrahedron Lett. 1997, 38, 6781-6784. 

The analogy between oxygen and nitrogen could not be extended to the formation of 2//-benz[e ][ 1,2]oxaborins from styrenes treatment of 2-hydroxystyrene with boron halides gave only tars. However, tolan-2,2 -diboronic acid was cyclized in the presence of alkali to give a product whose structure was suggested to be (198) (59TL(14)21). 

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