Cycloparaphenyleneacetylenes (CPPA) are carbon nanohoops consisted of fully-conjugated para-phenylenes and acetylenes. They have unique photophysical and supramolecular properties due to their curved pi-surfaces and strained alkynes. Kawase and Oda reported the first synthesis in 1996 using McMurry coupling for macrocyclization followed by a sequence of bromination/elimination. However, the macrocyclization resulted in a mixture macrocycles and oligomers with low yield. Our group used alkyne metathesis for the macrocyclization and solved the bottleneck step. However, the final reductive aromatization reaction was problematic in performing in large scale. Here, we present a new synthetic pathway toward preparing CPPAs in high yield and large scale.

Synthesis of Cycloparaphenyleneacetylene (CPPA) via Alkyne Metathesis

ACS Spring Meeting 2021

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