氨基酸功能化环辛烯单体的区域及立体选择性开环易位聚合

合成具有可控初级结构的侧链型氨基酸聚合物,使其与具有完全精确初级结构的生物大分子相媲美,在高分子合成化学中仍然是一个长期的挑战。 在本文中,设计与合成了(环辛基-2-烯-1-羰基)-L-亮氨酸酰胺甲酯(1)和(环辛基-2-烯-1-羰基)-L-亮氨酸酰胺(2),通过Grubbs二代催化的开环易位聚合,合成了具有高反式双键选择性、高头尾区域选择性的亮氨酸衍生均聚物以及共聚物,这些聚合物具有相对较窄的相对分子质量分布(1.3~1.6)。 当组成为n(1)：n(2)=50：50嵌段共聚物在丙酮中形成以亲水嵌段poly(2)为核,疏水嵌段poly(1)为壳的半径为30 nm的反相胶束。 然而,相同组成的无规共聚物则难溶于丙酮中。这些具有明确的区域及立体结构的氨基酸衍生聚合物为仿生材料的相关应用奠定了基础。

Regio-and Stereoselective Ring-Opening Metathesis Polymerization of Amino Acid Functionalized Cyclooctenes

Synthesis of side-chain amino acid-bearing polymers with controllable primary structures is still a long-term challenge in polymer chemistry compared to biomacromolecules(such as proteins and DNA)with completely precise microstructures.Here,we describe the synthesis of high trans-stereoregular(>99%)and high head-to-tail regioregularity(>99%)leucine-based homopolymers and block copolymers with relatively low polydispersities ranging from 1.3 to 1.6,using two designed monomers,namely(cyclooct-2-ene-1-carbonyl)-L-leucine methyl ester(1)and(cyclooct-2-ene-1-carbonyl)-L-leucine(2),via Grubbs 2nd catalyst at mild conditions.Importantly,the block copolymer of monomers 1 and 2 with molar ratio n(1):n(2)=50:50 is soluble in acetone to form reverse micelles with radius around 30 nm,which is composed of a hydrophilic core of poly(2)and a hydrophobic shell of poly(1).However,the random copolymers with the same proportion was partially insoluble in the solvent.These amino acid-bearing polymers with well-defined regio-/stereoregular structures provide the basis for relevant applications in biomimetic materials.