725264-48-2Relevant academic research and scientific papers
A highly selective catalytic system for the cross-coupling of (E)-Styryl Bromide with Benzeneboronic acid: Application to the synthesisof all-trans poly(arylenevinylene)s
Wakioka, Masayuki,Mutoh, Yuichiro,Takita, Ryo,Ozawa, Fumiyuki
supporting information; experimental part, p. 1292 - 1298 (2010/01/30)
Ahighlyselective system for palladium-catalyzed polycondensation of (E, E)-1,4-bis(2-bromoethenyl)benzene ((E, E)-1)with 2,5-dioctyloxybenzene-1,4- diboronicacid(2a)togive all-trans poly[(p-phenylenevinylene)-alt-(2,5- dioctyloxy-1,4-phenylenevinylene)] (all-trans 3) has been investigated using (E)-styryl bromide ((E)-4) and 2,5-dioctyl- oxybenzeneboronicacid(5a) as model compounds of and 2a, respectively. The reaction of (E)-4 and 5a in toluene in the presence of Pd(PPh3)4 catalyst and aqueous K 2CO3 base affords considerable amounts of homocoupling products (i.e., 1,4-diphenylbutadiene (13%) and 2,2',5,5'-tetraoctyloxybiphenyl (22%)), together with (E)-2,5-dioctyl- oxystilbene ((E)-6a) as the cross-coupling product (30%). The use of aqueous NaOH as a strong base and Bu4NBr as a phase-transfer catalyst notably reduces the homocoupling products, and the use of Pd(PBut3)2 instead of Pd(PPh3)4 results inalmost perfect selectivity of the cross-coupling product (E)-6a. Under optimized catalytic conditions, the desired all- trans 3 has been successfully prepared without notabledefects in the polymer chain.
