An alkyne-azide addition, i.e., click, reaction in conjunction with an electrostatic self-assembly and covalent fixation (ESA-CF) process has been demonstrated to effectively construct a variety of unprecedented multicyclic polymer topologies. A series of single cyclic poly(tetrahydrofuran), poly(THF), precursors having an alkyne group (Ia), an azide group (Ib), two alkyne groups at the opposite positions (Ic), and an alkyne group and an azide group at the opposite positions (Id) have been prepared by the ESA-CF process. Moreover, a bicyclic 8-shaped precursor having two alkyne groups at the opposite positions (Ie) was synthesized. The subsequent click reaction of Ia with linear (IIa) and three-armed star (IIb) telechelic precursors having azide groups has been performed to construct bridged-type two-way (IIIa) and three-way (IIIb) paddle-shaped polymer topologies, respectively. Likewise, spiro-type tandem tricyclic (IVa) and tetracyclic (IVb) topologies resulted from Ib/Ic and Ib/Ie, respectively. Furthermore, three types of multicyclic topologies that are composed of repeating ring (Va), alternating ring/linear (Vb), and alternating ring/star (Vc) units have been synthesized from Id, Ic/IIa, and Ic/IIb, respectively.

A tandem alkyne-azide addition, i.e., click, and an olefin metathesis condensation, i.e., clip, reactions in conjunction with an electrostatic self-assembly and covalent fixation (ESA-CF) process, have been demonstrated as effective means to produce constructions of programmed folding of polymers having doubly fused tricyclic and triply fused tetracyclic topologies. Thus, a series of cyclic poly(tetrahydrofuran), poly(THF), precursors having an allyloxy group and an alkyne group (Ia), an allyloxy group and an azide group (Ib), and two alkyne groups (Ic) at the opposite positions was prepared by means of the ESA-CF method. The subsequent click reactions of Ia with a linear telechelic poly(THF) precursor having azide end groups (Id) and of Ib with Ic afforded a bridged dicyclic polymer (IIa) and a tandem spiro tricyclic precursor (IIb), respectively, both having two allyloxy groups at the opposite positions of the ring units. Finally, the intramolecular metathesis condensation reaction of IIa and of IIb in the presence of a Grubbs catalyst was performed to construct effectively a doubly fused tricyclic and a triply fused tetracyclic polymer topologies (III and IV), respectively.

A pentacyclic quadruply fused polymer topology has been constructed for the first time through alkyne-azide addition (click) and olefin metathesis (clip) reactions in conjunction with an electrostatic self-assembly and covalent fixation (ESA-CF) process. Thus, a spiro-type, tandem tetracyclic poly(tetrahydrofuran), poly(THF), precursor having two allyloxy groups at the opposite positions of the four ring units was prepared by the click-linking of one unit of an eight-shaped precursor having alkyne groups at the opposite positions with two units of a single-cyclic counterpart having an azide and an alkene group at the opposite positions. Both are obtainable through ESA-CF. The subsequent metathesis clip-folding of the tetracyclic precursor could afford a pentacyclic quadruply fused polymer product, of "shippo" form, in 19% yield.

An alkyne−azide addition (click) reaction of a linear poly(tetrahydrofuran), poly(THF), precursor having an alkyne group at the center position and cyclic ammonium salt end groups has been applied with the complementary linear poly(THF) precursors having an azide group at single or both chain ends to produce asymmetric star-and H-shaped poly(THF) precursors having cyclic ammonium salt end groups. The subsequent electrostatic self-assembly and covalent fixation (ESA-CF) process after introducing dicarboxylate counteranions having an additional alkene or alkyne group could afford the designated kyklo-telechelic precursors, having either a tadpole form containing an alkyne group at the top-head and an alkene group at the tail-end positions or an isomeric manacle/theta form containing two alkene groups at the orthogonal positions. The further click coupling of the former with a linear telechelic precursor having azide groups followed by the metathesis folding (clip) process could produce effectively a doubly f used tricyclic polymer having β-graph topology. Moreover, the convergent folding by the clip reaction of the latter manacle/theta isomeric precursors could produce exclusively another doubly f used tricyclic polymer having γ-graph topology.

Ap entacyclic quadruply fused polymer topology has been constructed for the first time through alkyne-azide addition (click)a nd olefin metathesis (clip) reactions in conjunction with an electrostatic self-assembly and covalent fixation (ESA-CF) process.T hus,aspiro-type,t andem tetracyclic poly(tetrahydrofuran), poly(THF), precursor having two allyloxy groups at the opposite positions of the four ring units was prepared by the click-linking of one unit of an eightshaped precursor having alkyne groups at the opposite positions with two units of as ingle-cyclic counterpart having an azide and an alkene group at the opposite positions.B oth are obtainable through ESA-CF.T he subsequent metathesis clip-folding of the tetracyclic precursor could affordapentacyclic quadruply fused polymer product, of "shippo" form, in 19 %y ield.The programmed folding of polymer molecules,w hich is widely observed in diverse biopolymer events including DNA packaging and protein 3D structure formation, has also been highlighted in av ariety of cyclic peptides,c yclotides,c onstructing fused multicyclic structures formed through the intramolecular SÀSb ridging with cysteine residues,t obe crucial for their extraordinary stability and bioactivity. [1,2] Notably,inparticular, atopologically intriguing,prototypical non-planar K 3,3 -graph construction, which cannot be embedded in the plane in such away that its edges intersect only at their endpoints,h as recently been identified in cyclotides from diverse origins. [1,3] Thee ffective and programmed folding by synthetic polymers into designated multicyclic forms,o nt he other hand, has been an ongoing challenge in polymer chemistry. [4] We have developed an electrostatic self-assembly and covalent fixation (ESA-CF) method [5] for the programmed polymer folding in which linear, star, and other branched telechelic precursors having cyclic ammonium salt groups carrying plurifunctional carboxylate counteranions were employed to form polymeric self-assemblies as key intermediates.T he three forms of dicyclicc onstructions,t hat is, q (fused), 8( spiro), and manacle (bridged), as well as at refoil (spiro-tricyclic) construction have been effectively produced through the ESA-CF process. [5,6] Ac lass of fused multicyclic polymer topologies,r ather than their spiro and bridged counterparts,a re particularly attracting not only by their relevance to their programmed folding of cyclotides but also from the significanse of topological geometry conjectures [5,7] (Scheme 1). Thus,atetracyclic triply fused macromolecular K 3,3 -graph has been constructed through the ESA-CF method using au niformsize dendritic polymer precursor having six cyclic ammonium salt end groups carrying two units of at rifunctional carboxylate counteranions,a nd subsequent covalent conversion by the ring-opening reaction of cyclic ammonium salt groups at an elevated temperature under dilution.[8]Moreover,atandem alkyne-azide addition (click) and olefin metathesis (clip) reaction in conjunction with the ESA-CF proces...