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A new N-alkynylated dithieno[3,2- b :2′,3′- d ]pyrrole (DTP) monomer was synthesized using a Buchwald–Hartwig amination of 3,3′-dibromo-2,2′-bithiophene with pent-4-yn-1-amine. The obtained monomer was investigated for the possibility of a pre-polymerization modification via Huisgen 1,3-dipolar cycloaddition (“click”) reaction with azide-containing organic compounds. The synthesized N-alkynylated DTP monomer is soluble in a number of organic solvents and reacts with organic azides via “click” reactions in mild conditions, achieving high yields. The N-alkynylated DTP monomer and its “click”-modified derivative can be electropolymerized to form polymeric films. Herein, the synthesis and characterization of a “click” modified DTP monomer, its pre-modified derivative, and their corresponding polymers are described. The developed method is a facile route to synthesize a new generation of various N-functionalized DTP homopolymers.
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Site-selective [2 + 2 + n ] cycloadditions for rapid, scalable access to alkynylated polycyclic aromatic hydrocarbons
Polycyclic aromatic hydrocarbons (PAHs) are attractive synthetic building blocks for more complex conjugated nanocarbons, but their use for this purpose requires appreciable quantities of a PAH with reactive functional groups. Despite tremendous recent advances, most synthetic methods cannot satisfy these demands. Here we present a general and scalable [2 + 2 + n ] ( n = 1 or 2) cycloaddition strategy to access PAHs that are decorated with synthetically versatile alkynyl groups and its application to seven structurally diverse PAH ring systems (thirteen new alkynylated PAHs in total). The critical discovery is the site-selectivity of an Ir-catalyzed [2 + 2 + 2] cycloaddition, which preferentially cyclizes tethered diyne units with preservation of other (peripheral) alkynyl groups . The potential for generalization of the site-selectivity to other [2 + 2 + n ] reactions is demonstrated by identification of a Cp 2 Zr-mediated [2 + 2 + 1]/metallacycle transfer sequence for synthesis of an alkynylated, selenophene-annulated PAH. The new PAHs are excellent synthons for macrocyclic conjugated nanocarbons. As a proof of concept, four were subjected to alkyne metathesis catalysis to afford large, PAH-containing arylene ethylene macrocycles, which possess a range of cavity sizes reaching well into the nanometer regime. Notably, these high-yielding macrocyclizations establish that synthetically convenient pentynyl groups can be effective for metathesis since the 4-octyne byproduct is sequestered by 5 Å MS. Most importantly, this work is a demonstration of how site-selective reactions can be harnessed to rapidly build up structural complexity in a practical, scalable fashion.
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- Award ID(s):
- 1708210
- PAR ID:
- 10207943
- Date Published:
- Journal Name:
- Chemical Science
- Volume:
- 11
- Issue:
- 11
- ISSN:
- 2041-6520
- Page Range / eLocation ID:
- 3028 to 3035
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/C9SC06102A
