Benzene-1,4-diboronic acid

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... 

Weber and Thomas [270] prepared rigid poly(p-phenylene)-type polymeric networks by reacting tetrafunctional building blocks of tetrabrominated 9,9 -spirobifluorene with benzene-1,4-diboronic acid or 4,4 -biphenyldiboronic acid in a mixed organic solvent. Here, the contorted unit of spirobifluorene forces the four polyphenylene chains to grow in four different directions. 

Solid polymer electrolytes have been actively pursued as a major contribution to the development of high-energy density batteries, particularly lithium secondary batteries. The poly(p-phenylene)s substituted with oligo(oxymethylene) side chains and blends of these novel polymers with lithium salts are achieved by biaryl coupling of benzene-1,4-diboronic acids (Fig. 4). ° OctapoIy(p-phenylene) functions as the artificial ion channel which specially recognizes (bio)membranes by their thickness (Fig. 5). ... 

An improved procedure for benzene diboronic acid and ester (50-60%) Todd, M. H. Balasubramanian, S. Abell, C. Tetrahedron Lett. 1997,38, 6781. 

HB polyarylenes were synthesized by two research groups via different C-C coupling methods. Smet et. al [65]. studied the condensation of isatins with a trifiinctional phenyl ether (see Formula 10.3). Trifluoromethane sulfonic acid served as catalyst and the low monomer concentration prevented gelation. This approach is, in principle, a variant of the acid catalyzed aldehyde-phenol polycondensation developed more than 100 years before for the production of Novolac and Bakelite (see Chap. 2). Possum et al. [66]. studied Pd-catalyzed polycondensations of 1,4-benzene diboronic acid with tri(4-bromophenyl)phosphioxide (see Formula 10.3). 

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... 

A solution of the pinacol ester of diboronic acid (1 mmol), l-bromo-3,4-methylenedioxy benzene (2 mmol), 10% Pd/C (80mg) and CS2CO3 (3.7 mmol) were dissolved in 10ml methyl alcohol and heated to 55 °C 16 hours. GC analysis indicated that the product constituted of 83.5% 2-(bisl,3-benzodioxole and 16.5% l-bromo-3,4-methylenedioxy)benzene. 

We discovered that the addition of pyridine to a tetrahydrofuran (THF) solution of benzene-l,4-diboronic acid (BDBA) and 1,2,4,5-tetrahydroxybenzene (THB) induced hierarchical molecular self-assembly to give well-defined submicrospheres (Figure 12.1). ... 

Kubo and Nishiyabu describe the use of reversible boronate esterification to build well-ordered microparticles through supramolecular polymerisation of benzene-l,4-diboronic acid with tetraols. When pentaerythritol is used as the tetraol component for self-assembly, thermodynamically stable flower-like microparticles are produced. Surface functionalisation enables formation of nanometal-deposited heterogeneous catalysts and white-light-emissive chemosensors. 

In 1992, the same group reported the synthesis of various 4,4"-disubstituted terphenyls by the reaction of para diboronic acids (37) with j ara-bromo-Y functionalized benzenes (38) [75] (Scheme 6.23). 

When a-oximehydrazones were used as the chelating agents, researches succeeded in the synthesis of mono- and bis-clathrochelate iron and cobalt(II) oximehydrazonates [185-187], At the first stage, mono- and bis-semiclathrochelate iron and cobalt(II) complexes were isolated by a cross-linking with phenylboronic or ferrocenylboronic acids, and with benzene-1,4-diboronic or l,l -ferrocenyldiboronic acids. 

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