Circular Discovery in Small Molecule and Conjugated Polymer Synthetic Methodology

Abstract

Simple and efficient methods are a key consideration for small molecule and polymer syntheses. Direct arylation polymerization (DArP) is of increasing interest for preparing conjugated polymers as an effective approach compared to conventional cross-coupling polymerizations. As DArP sees broader utilization, advancements are needed to access materials with improved properties and different monomer structures and to improve the scalability of conjugated polymer synthesis. Presented herein are considerations for developing new methods of conjugated polymer synthesis from small molecule transformations, exploring how DArP has successfully used this approach, and presenting how emerging polymerization methodologies are developing similarly. While it is common to adapt small molecule methods to polymerizations, we demonstrate the ways in which information gained from studying polymerizations can inform and inspire greater advancements in small molecule transformations. This circular approach to organic synthetic method development underlines the value of collaboration between small molecule and polymer-based synthetic research groups.

Group 16 conjugated polymers based on furan, thiophene, selenophene, and tellurophene

“…Recently, direct arylation polymerization (DArP) has been advanced rapidly and established as a promising tool for the synthesis of CPs, as highlighted in several reviews. [85][86][87][88][89] DArP features dehydrohalogenative cross-coupling reactions between halogenated (hetero)arenes and non-functionalized (hetero)arenes. Due to the direct use of C-H bonds, DArP circumvents the installation of organometallic functionalities, which improves atom economy and generates environmentally benign byproducts.…”

Synergistic catalysis for the synthesis of semiconducting polymers

“…c DArP of indole and d newly proposed direct arylation mechanism. Reproduced with permission from the American Chemical Society [66] Scheme 17 Room-temperature benzofuran direct arylation by aryl iodide using hexafluoroisopropanol (HFIP) as the solvent. Reproduced with permission from the American Chemical Society [64] that transferring the equivalent small-molecule reactions to polymerization has not always worked.…”

Recent Advances in Room-Temperature Direct C–H Arylation Methodologies

“…Several reviews and personal accounts provide a systematic analysis of direct C-H arylation reactions in general 12,15,18 as well as on specific topics such as directinggroup-assisted arylation, direct arylation polymerization, 19,20 sustainable approaches, 21,22 and mild C-H activation. 23 Nonetheless, a detailed analysis of C-H bond activation at ambient temperature is lacking.…”

“…17 Since then, various methods enabling C-H bond activation at room temperature have been realized, further reducing the environmental and economic footprint of direct C-H arylation reactions. Several reviews and personal accounts provide a systematic analysis of direct C-H arylation reactions in general 15,18,19 as well as on specific topics such as directing group assisted arylation, direct arylation polymerization, 20,21 and sustainable approaches, 22,23 mild C-H activation 24 . Nonetheless, a detailed analysis of C-H bond activation at ambient temperature is lacking.…”