Concise Click/ESA-CF Synthesis of Periodically-Positioned Trifunctional kyklo-Telechelic Poly(THF)s

A concise two-step click/ESA-CF process has been developed to prepare a kyklo-telechelic poly(tetrahydrofuran), poly(THF), having three functional groups at the constant intervals. Thus, a key linear precursor (I), having N-phenylpyrrolidinium salt groups at the chain ends and having two hydroxyl groups at the prescribed inner positions, has been prepared through the alkyne−azide addition (click) reaction using one unit of a linear telechelic poly(THF) having a pair of an alkyne and a hydroxyl groups (1) and two units of a linear asymmetric telechelic poly(THF) having an azide and an N-phenylpyrrolidinium salt group (2). The subsequent polymer cyclization by means of an electrostatic self-assembly and covalent f ixation (ESA-CF) process, by employing a dicarboxylate counteranion having an additional alkyne group (3) to I, could produce a trifunctional kyklo-telechelic poly(THF) (II), having two hydroxyl and one alkyne groups positioned at the constant intervals along the ring polymer backbone. The subsequent esterification of the hydroxyl groups in II was performed to give a kyklo-telechelic poly(THF) having three alkyne groups at the constant intervals (III), and a further click reaction of III with 2 was conducted to produce a ring polymer product having three emanating graft segments at the constant intervals along the ring unit (IV), i.e., a three-tail tadpole topology.