Boronate oligomers, synthesis

Catalysts used in the polymerization of C-5 diolefins and olefins, and monovinyl aromatic monomers, foUow closely with the systems used in the synthesis of aHphatic resins. Typical catalyst systems are AlCl, AIBr., AlCl —HCl—o-xylene complexes and sludges obtained from the Friedel-Crafts alkylation of benzene. Boron trifluoride and its complexes, as weU as TiCl and SnCl, have been found to result in lower yields and higher oligomer content in C-5 and aromatic modified C-5 polymerizations. 

The solvent-free, microwave-assisted coupling of thienyl boronic acids and esters with thienyl bromides, using aluminum oxide as the solid support, served to rapidly check the reaction trends on changing times, temperature, catalyst, and base and easily optimize the experimental conditions to obtain the desired product in fair amounts. This procedure offers a novel, general, and very rapid route to the preparation of soluble thiophene oligomers. Quaterthiophene 265 was obtained in 6 min by reaction of 2-bromo-2,2 -bithiophene with bis(pinacolato)diborane(4) in 65% yield, whereas dithiophene 266 was obtained with 70% yield. The synthesis of new chiral 2,2 -bithiophenes also was reported. The detailed... 

Synthesis of Boron-rich Building Blocks for Phosphodiester Oligomers in Boron Neutron Capture Therapy... 

Drechsel, K. Lee, C.S. Leung, E.W. Kane, R.R. Hawthorne, M.F. Synthesis of new building blocks for boron-rich oligomers in boron neutron capture therapy (BNCT). 1. Tetrahedron Lett., 35,6217-6220,1994. 

Reaction Mechanism of Boron Modified Prepolymer Synthesis. The Source for the Dimethylene Ether Bridge is a Dimer and higher Oligomers, as Shown in the Transition State. 

Kagan reported in 1983 the synthesis of the whole series of H—T —H via organoboranes [26d]. The oligomers can be prepared separately in acceptable yields with organoborane reagents. To a solution of Li—T —H 9, 15, 16, 28, the 9-methoxy derivative of 9-borabicyclo[3.3.1]nonane is added and a corresponding boronated thiophene 29-32 is formed [Eq. (12)]. After neutralization with boron trifluoride etherate, a second Li—T -H, which may differ from the previous one, is added to boranes 33-36 and the resulting complex 37-41 is oxidized with iodine in order to... 

The method employed for the synthesis of boronated oligonucleotides is similar to the phosphoramidite method used for the synthesis of normal oligomers, except that the oxidation step has been replaced by reaction with dimethylsulfide-borane. Scheme 1. Yields have not been optimized. 

As allyl components for IPN synthesis the following compounds were used diethylene glycol bis(allyl carbonate) (DEGAC), diallyl phthalate (DAP), dial-lyl adipate (DAA), and the commercial product of condensation of monoallyl maleinate and epoxy oligomer ED-20. Polymerization of diallyl compoimds by formation of IPNs had been performed in the presence of 5 mass % of dibenzoyl peroxide for DEGAC and diciunyl peroxide. As a hardener of epoxy oligomer, complexes of boron trilluoride with an aniline and benzylamine have been used. 

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