Thexylborane, hydroboration polymerization

The preparation of a functional segmented block copolymer was also investigated (scheme ll).15 First hydroboration polymerization of the oligomer using thexylborane was carried out. Then the obtained organoboron polymer was subjected to a chain-transformation reaction (DCME rearrangement). DCME and lithium alkoxide of 3-ethyl-3-pentanol in hexane was added to a THF solution of the polymer at 0°C. 

In the present hydroboration polymerization, thexylborane was employed as a monoalkylborane (bifunctional hydroborane) component because thexylborane is known to be stable enough after distillation. As a diene monomer, relatively longer chain dienes were used to avoid the... 

As summarized in Table 1, this hydroboration polymerization can be applied to various combinations of dienes such as 1,9-decadiene, p-divinylbenzene, p-diallylbenzene, bis(allyl ether)s of ethylene glycol, tetramethylene glycol, triethylene glycol, hydroquinone and bisphenol-A with thexylborane to produce the corresponding organoboron polymers. 

Scheme 2 demonstrates the versatile reactions of organoboron polymers prepared by hydroboration polymerization. For example, the polymer prepared from thexylborane and 1,7-octadiene was reacted with carbon monoxide at 120°C followed by treatment with NaOH and H2O2 to produce a poly alcohol [7]. This conversion includes the migrations of polymer chain and thexyl group from boron atom to carbon as shown in Scheme 3. When this reaction was carried out under milder condition,...

For the selective preparation of polyketone, the organoboron polymer prepared by hydroboration polymerization between thexylborane and 1,7-octadiene was subjected to reaction with KCN [8]. After oxidation of the reaction mixture followed by coagulation, the desired polyketone was obtained selectively. The polymer formed was a... 

As a typical example for hydroboration polymerization of internal diyne, the reaction of 3,9-dodecadiyne and thexylborane was carried out in THF at 0°C under nitrogen (20). The polymerization behavior was quite similar to hydroboration polymerization of dienes. The organoboron polymer obtained was a colorless wax and soluble in common organic solvents such as benzene, THF or chloroform. An IR spectrum of the polymer showed the absorption band assignable to C=C bond, which was also supported by H- and B-NMR spectra. 3,8-Undecadiyne and 3,10-tridecadiyne were also used in hydroboration polymerization with thexylborane to produce the corresponding organoboron polymers. 

As an alternative method for the preparation of polyalcohols from organoboron polymers, dichloromethyl methyl ether (DCME) can be used (23). Various organoboron polymers prepared by hydroboration polymerization of dienes and thexylborane were reacted with DCME at 0°C in THF followed by treatment with lithium triethylmethoxide. After oxidative treatment with NaOH and H2O2, the corresponding poly(alcohol)s were obtained. The... 

Hydroboration of terminal diyne gives organoboron polymer having branched structure due to the further hydroboration reaction toward the initially formed vinylborane structures. That is, terminal diynes are taken to have a potential as a multifunctional monomer. When the polymerization between 1,7-octadiene and thexylborane was carried out in the presence of a small amount of 1,7-octadiyne, the molecular weights of organoboron polymers were found to be increased when the ratio of diyne/diene was increased [5]. 

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