Hexamethyldisilazane-mediated controlled polymerization of α-Amino acid N-carboxyanhydrides
Hexamethyldisilazane-mediated controlled polymerization of α-Amino acid N-carboxyanhydrides
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DOI：
10.1021/ja074961q
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发表时间：
2007-11-21
影响因子：
15
通讯作者：
Cheng, Jianjun
中科院分区：
文献类型：
--
作者：
Lu, Hua;Cheng, Jianjun
α-氨基酸N-羧酸酐(NCA)以胺为引发剂进行开环聚合，通常形成相对分子质量不可控且分子量分布较宽的多肽。然而，我们发现，六甲基二硅氮烷(HMDS)介导的受控NCA聚合得到的多肽具有可预测的相对分子质量和窄的相对分子质量分布。通过MS、核磁共振和FT-IR分析，证明了引发步骤涉及HMDS N-Si键的断裂和氨基甲酸三甲基硅酯(TMS-CBM)末端基团的形成。多肽链通过TMS-CBM末端基团的TM迁移到传入单体上而传播，并形成新的TMS-CBM端基。这种有机硅试剂介导的NCA聚合提供了一种无金属的策略，可以方便地合成具有可预测的相对分子质量和窄的相对分子质量分布的同质或嵌段多肽。
Ring-opening polymerizations of alpha-amino acid N -carboxyanhydrides (NCAs) initiated with amines typically form polypeptides with uncontrolled molecular weights and broad molecular weight distributions. However, we found that hexamethyldisilazane (HMDS)mediated controlled NCA polymerizations gave polypeptides with predictable molecular weights and narrow molecular weight distributions. Using MS, NMR, and FT-IR, we demonstrated that the initiation step involved the cleavage of the N-Si bond of HMDS and the formation of a trimethylsilyl carbamate (TMS-CBM) terminal group. Polypeptide chains were propagated through the migration of TMS of the TMS-CBM end group to the incoming monomer and formed a new TMS-CBM terminal group. This organosilicon reagent mediated NCA polymerization offers a metal-free strategy for the convenient synthesis of homo- or block polypeptides with predictable molecular weights and narrow molecular weight distributions.