Selective Radical Addition with a Designed Heterobifunctional Halide: A Primary Study toward Sequence-Controlled Polymerization upon Template Effect
Selective Radical Addition with a Designed Heterobifunctional Halide: A Primary Study toward Sequence-Controlled Polymerization upon Template Effect
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DOI：
10.1021/ja9031314
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发表时间：
2009-08-12
影响因子：
15
通讯作者：
Sawamoto, Mitsuo
中科院分区：
文献类型：
--
作者：
Ida, Shohei;Terashima, Takaya;Sawamoto, Mitsuo
钌（II）催化，高选择性，定量自由基加成的烯烃，甲基丙烯酸（MAA），已经实现了模板卤化物(2)含有内置胺基作为识别位点的底物的羧基。胺模板（1:1摩尔比）对MAA的特异性离子结合导致优先形成1:1的MAA-2加合物，而没有模板的类似卤化物即使在外部添加胺的情况下也会诱导MAA寡聚化。MAA与其酯形式[甲基丙烯酸甲酯（MMA）]在卤化物上的竞争性自由基加成进一步表明，相对于非模板卤化物的结果，分子内模板引入对2的底物选择性[k'(MAA)/k'(MMA)]提高了10倍以上。这些特异性很可能是由MAA中羧基通过酸选择性模板胺的特异性相互作用（识别）引发的，该模板胺被植入2中自由基加成位点附近。这些结果表明了在精确聚合中控制重复单元序列的可能性。
A ruthenium(II)-catalyzed, highly selective, quantitative radical addition of an alkene, methacrylic acid (MAA), has been achieved by using a template halide (2) containing a built-in amine group as a recognition site for the carboxyl group of the substrate. The specific ionic binding of MAA by the amine template (1:1 molar ratio) led to preferential formation of the 1:1 MAA-2 adduct, whereas a similar halide without a template induced MAA oligomerization even in the presence of an externally added amine. A competitive radical addition of MAA versus its ester form [methyl methacrylate (MMA)] on the halide further demonstrated that the substrate selectivity [k'(MAA)/k'(MMA)] for 2 is enhanced more than 10 times by the intramolecular introduction of the template relative to the result for the nontemplate halide. These specificities are most likely triggered by the specific interaction (recognition) of the carboxyl group in MAA via the acid-selective template amine, which is implanted in the close vicinity of the radical addition site in 2. These results intimate possibility of control over the repeat-unit sequence in precision polymerization.