Ferulic acid, a natural cinnamic acid derivative with hydroxyl and methoxy group, was quantitatively converted into protected functional styrene monomers 4–vinylguaiacol (VG) as an intermediate. In a facile and scalable two-step reaction including decarboxylation followed by protection reactions, the monomers 1-ethoxy ethoxy-VG and -butyldimethylsilyl-VG were obtained in high yields. Living anionic polymerization of the acetal (1-ethoxy ethoxy-) and silyl (-butyldimethylsilyl-) protected styrenes proceeded to well-defined polymers with narrow MWD, although the reaction temperatures in THF were dependent on the protecting groups of the monomers. Deprotection of the acetal and silyl groups was conveniently attained under acidic conditions both in THF and water, resulting in well-defined poly(vinylguaiacol). In addition, demethylation with boron tribromide was performed to obtain poly(vinylcatechol) copolymers, which were used to complex Fe(III). Random copolymerization was observed for the statistical EE-VG and styrene copolymerization in THF at –95 °C. Aiming at a fully biobased approach, 4-isopropylstyrene was synthesized from cuminaldehyde by Wittig reaction, and the copolymerization of the latter with EE-VG was also performed, resulting in multi-hydroxyl functional macroinitiators after deprotection, which were employed for subsequent L-lactide and 4-methyl-ε-caprolactone grafting.

中文翻译：

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阿魏酸衍生的取代苯乙烯单体的阴离子聚合

阿魏酸是一种带有羟基和甲氧基的天然肉桂酸衍生物，作为中间体被定量转化为受保护的功能性苯乙烯单体4-乙烯基愈创木酚（VG）。在包括脱羧和保护反应在内的简便且可扩展的两步反应中，以高产率获得了单体 1-乙氧基乙氧基-VG 和丁基二甲基甲硅烷基-VG。尽管在 THF 中的反应温度取决于单体的保护基团，但缩醛（1-乙氧基乙氧基-）和甲硅烷基（-丁基二甲基甲硅烷基-）保护的苯乙烯的活性阴离子聚合可生成具有窄 MWD 的明确聚合物。在酸性条件下，在THF和水中，可以方便地实现缩醛和甲硅烷基的脱保护，得到结构明确的聚(乙烯基愈创木酚)。此外，用三溴化硼进行脱甲基化以获得聚(乙烯基儿茶酚)共聚物，其用于络合Fe(III)。在 –95 °C 的 THF 中统计 EE-VG 和苯乙烯共聚时观察到无规共聚。针对全生物基方法，以异丙苯醛为原料，通过Wittig反应合成4-异丙基苯乙烯，并与EE-VG进行共聚，脱保护后得到多羟基功能性大分子引发剂，用于后续L-丙交酯的制备和4-甲基-ε-己内酯接枝。