Synthesis of Ring-Locked Tetracyclic Dithienocyclopentapyrans and Dibenzocyclopentapyran via 1,5-Hydride Shift and Copper-Catalyzed C–O Bond Formation for Nonfullerene Acceptors

Abstract

We discovered a unique synthetic route to construct 2H-pyran-containing tetracyclic dithienocyclo­pentapyran (DTCP) and dibenzocyclo­pentapyran (DBCP) architectures. The synthesis involves an acid-induced dehydration cyclization followed by a [1,5] hydride-shift isomerization to form a cyclopentanone moiety which was converted to the pyran-embedded tetracyclic products by a CuI-catalyzed intramolecular C–O bond formation in good yield. DTCP was used as a building block to prepare an acceptor–donor–acceptor (A–D–A) type n-type material DTCP-BC leading to a solar cell efficiency of 9.32%.

Conjugated polymers and small molecules containing the thiophene–vinylene–thiophene (TVT) unit for organic photovoltaic applications

“…Cheng et al developed an all-fused TVT derivative dithienocyclopentapyran (DTCP), with which as the electron-donor they obtained an A–D–A type narrow-bandgap molecule M6 . 114 When PBDB-T was selected as the donor, the devices delivered a decent PCE of 9.32%. Recently, Zhu et al developed another two all-fused TVT building blocks, 4,8-dihydropentaleno[1,2- b :4,5- b ′]dithiophene (PDT) and 4,8-dihydropentaleno[1,2- b :4,5- b ′]dithieno[3,2- b :2′,3′- d ]thiophene (PDTT) when they were end-capped by two 2-(5,6-difluoro-3-oxo-2,3-dihydro-1 H -inden-1-ylidene)malononitrile (DFIC) groups, generating two SMs M7 and M8 .…”