Organoboron polymer synthesis

Much attention has recently been focused on organoboronic acids and their esters because of their practical usefulness for synthetic organic reactions including asymmetric synthesis, combinatorial synthesis, and polymer synthesis [1, 3, 7-9], molecular recognition such as host-guest compounds [10], and neutron capture therapy in treatment of malignant melanoma and brain tumor ]11]. New synthetic procedures reviewed in this article wiU serve to find further appHcations of organoboron compounds. 

In addition to hydroboration, haloboration and phenylboration have also been used in the synthesis of 7r-conjugated organoboron polymers (9)29 (Fig. 9) and polymers containing B—N bonds.30... 

The synthesis of comblike organoboron polymer was examined (see scheme 2) by dehydrocoupling polymerization of hydroborane monomers bearing an... 

A synthesis of comblike organoboron polymer/boron stabilized imidoanion hybrids was examined via reactions of poly(organoboron halides) with 1-hexylamine and oligo(ethylene oxide) monomethyl ether and subsequent neutralization with lithium hydride (scheme 8). The obtained polymers (10) were amorphous soft solids soluble in common organic solvents such as methanol, THF, and chloroform. In the nB-NMR spectra (Fig. 11), neutralization of the iminoborane unit with lithium hydride... 

Some procedures to prepare main-chain polymeric boron Lewis acids have been also developed. The most commonly used method for the synthesis of main-chain organoboron polymers is the hydroboration polymerization developed by Chujo [29, 30]. For example, hydroboration between (47) and (48) in TH F gave the organoboron... 

Matsumi N, Chujo Y (1997) Synthesis of novel organoboron polymers by hydroboration polymerization of bisaUene compounds. 38. Polym BuU (Berl) 38(5) 531-536. doi 10.1007/s002890050083 Andreou A (2013) Synthesis tmd reactivity of boron hydrides for the preparation of chiral diboranes and bis-phosphines. University of Cambridge, Cambridge 39. 

The organoboron polymers prepared by hydroboration polymerization have a new structure consisting of C-B bonds in the main chain. Generally, these organoboron polymers can be regarded as a polymer homologue of trialkylborane, which is known to be a very versatile compound in organic synthesis [6]. In other words, the obtained polymers by hydroboration polymerization can be expected as a novel type of reactive polymers. 

The synthesis of luminescent organoboron quinolate polymers (21) (Fig. 15) via a three-step procedure starting from a silylated polystyrene has been communicated. The synthesis was initiated by the highly selective borylation of poly (4-trimethylsilylstyrene) (PS-Si), followed by the replacement of the bromine substituents in poly(4-dibromoborylstyrene) (PS-BBr) with substituted thienyl groups (R = H, 3-hexyl, 5-hexyl). In the final step, the 8-hydroxyquinolato moiety was introduced. The hexyl-substituted polymers efficiently emitted light at 513-514nm upon excitation at 395 nm.40... 

N. Matsumi, M. Miyata, and Y. Chujo, Synthesis of organoboron Tr-conjugated polymers by hydroboration polymerization between heteroaromatic diynes and mesitylborane and their light emitting properties, Macromolecules, 32 4467-4469, 1999. 

The use of solid supported, recyclable catalysts, is a well-assessed technique in classic organic chemistry, and many exhaustive reviews dealing with this subject are available [105, 115]. The use of solid supported catalysts for library synthesis in solution has also been reported. Among others, Kobayashi et al. presented the use of a new supported scandium catalyst for 3CC reactions leading to solution libraries of amino ketones, esters, and nitriles (24-member model discrete library) [116], or to quinolines (15-member model discrete library) [117], and Jang [118] presented a polymer bound Pd-catalyzed Suzuki coupling of organoboron compounds with halides and triflates. This area was also briefly reviewed recently [119]. 

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