Effective Click Construction of Bridged- and Spiro-Multicyclic Polymer Topologies with Tailored Cyclic Prepolymers (kyklo-Telechelics)

Abstract

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.

Topological polymer chemistry for designing multicyclic macromolecular architectures

“…54 Tandem spiro-multicyclic polymers with multiple ring units were also produced by the click self-polycondensation of a cyclic precursor with alkyne and azide groups at opposite positions of the ring unit, which is obtainable by the ESA-CF technique (Scheme 8). 54 Bridged-multicyclic constructions Among a series of bridged-multicyclic constructions (Scheme 9), a dicyclic manacle-shaped polymer was obtainable in conjunction with a y-shaped polymeric isomer through the ESA-CF with an assembly composed of three linear bifunctional precursor units carrying two trifunctional carboxylate counteranion units (Scheme 10), as described in the previous section. 18,19 The ESA-CF procedure was also applicable to an assembly composed of two starshaped trifunctional precursor units carrying three bifunctional carboxylate counteranion units (Scheme 10).…”

“…21 The selective construction of a dicyclic, manacle-shaped polymer topology was achieved through the click coupling of a bifunctional linear telechelic precursor containing azide groups with a cyclic polymer precursor bearing an alkyne group obtainable through the ESA-CF protocol (Scheme 10). 54 Likewise, a bridged-tricyclic three-way paddle-shaped polymer was obtained by the relevant click coupling reaction between a star-shaped trifunctional precursor containing azide groups with a cyclic polymer precursor bearing an alkyne group (Scheme 10). 54 Bridgedmulticyclic polymers consisting of cyclic and linear or branched polymer units were also produced by the click polycondensation of a cyclic precursor containing two alkyne groups at the opposite positions of the ring unit from the respective linear/branched telechelic precursors with azide groups (Scheme 10).…”

Topological Polymer Chemistry in Pursuit of Elusive Polymer Ring Constructions

“…5 They are subjected to further topological transformation by taking advantage of effective inter-and intramolecular covalent-linking processes, such as a ring-closing metathesis (RCM) in the presence of a Grubbs catalyst, 12,22 a palladium-mediated coupling reaction, 23 or the "click" process. 24 As for the latter two processes, the introduction of the relevant functional groups could be achieved by the esterification of the hydroxyl groups with the corresponding carboxylate derivatives. In particular, the metathesis condensation has been proven as a versatile means to cause effective polymer cyclization even under dilution with functional group tolerance (Scheme 3).…”

A novel strategy towards cyclic aliphatic (co)polyesters

“…Therefore, synthesis of well-defined macrocycles, extending over a large range of macromolecular characteristic features is of the utmost importance for improving basic knowledge and ultimately mimicking compounds with a specific biological activity. The main approaches to macrocycles are based on the end-to-end ring-closure (coupling) of homo-or hetero-difunctional linear precursors under very high dilution by any reaction known in the state of the art, such as nucleophilic substitution [7,8], addition on unsaturations [9][10][11][12][13], metathesis reaction [14][15][16], amidification [17], 'click' reaction [18][19][20][21][22], and electrostatic interaction followed by covalent…”