Orthogonal C-B Bond Transformation as an Approach for Versatile Synthesis of End-Functionalized Polymers
Orthogonal C-B Bond Transformation as an Approach for Versatile Synthesis of End-Functionalized Polymers
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DOI：
10.1021/acsmacrolett.2c00207
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发表时间：
2022-05-17
影响因子：
7.015
通讯作者：
Ouchi, Makoto
中科院分区：
文献类型：
--
作者：
Kanazawa, Tomoaki;Nishikawa, Tsuyoshi;Ouchi, Makoto
通过正交侧链取代端基和重复单元合成了传统上难以获得的端基功能化乙烯基聚合物，然后通过RAFT聚合合成了端基为异丙烯基硼酸酯的聚合物(IPBpin)，然后在钴(Co)催化的端烯基化反应中得到了端基带有C(Sp2)-B键和重复单元中带有C(Sp3)-B键的聚合物。其中，末端的C(Sp2)-B键是通过钯(Pd)催化的Suzuki-Miyaura交叉偶联选择性地转化的，随后重复的C(SP3)-B单元的转化得到了末端带有各种官能团的聚(α-甲基乙烯醇)[聚(MVA)]。基于硼的分步聚合反应克服了端基官能化聚(MVA)的合成困难，这是由于相应的醋酸异丙烯单体聚合能力差造成的。
Conventionally inaccessible end-functionalized vinyl polymers were synthesized via orthogonal side-chain replacement for terminal and repeating units of poly(alkenyl boronate)s. A terminal-defined polymer of isopropenyl boronic acid pinacol ester (IPBpin) was synthesized via RAFT polymerization, and subsequent cobalt (Co)-catalyzed end olefination afforded the polymer carrying the C(sp2)-B bond at the terminal and the C(sp3)-B bond in repeating units. Herein, the terminal C(sp2)-B bond was selectively transformable via palladium (Pd)-catalyzed Suzuki-Miyaura cross coupling, and subsequent transformation of the repeating C(sp3)-B unit gave the poly(alpha-methyl vinyl alcohol) [poly(MVA)] bearing various functional groups at the terminal. The boron-based stepwise polymer reaction thus overcame the synthetic difficulty of the end-functionalized poly(MVA), which is ascribed to the poor polymerization ability of the corresponding acetate monomer, i.e., isopropenyl acetate.