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submitted on 30.07.2020 and posted on 31.07.2020by Andrew Eisterhold, Steffen Otterbach, Stefan Bräse, Patrick Weis, Xiqu Wang, Ksenia V. Kutonova, Ognjen Miljanic
Cyclobenzoins are stable and shape-persistent macrocycles which offer promise as components of optoelectronic and porous materials. We report three new cyclotetrabenzoins, derived from biphenyl, naphthalene, and tolane skeletons. Their synthesis relied on the N-heterocyclic carbene-catalyzed benzoin condensation. Isolated as their acetic esters, these compounds are characterized by structures similar in shape, but larger in size than the parent cyclotetrabenzoin. Alkyne groups of the tolane-based cyclotetrabenzoin were post-synthetically functionalized with Co2(CO)6 moieties under mild reaction conditions.
We acknowledge the support from the US National Science Foundation (award DMR-1904998 to O. Š. M.), the Welch Foundation (award E-1768 to O. Š. M.), the donors of the American Chemical Society Petroleum Research Fund (award ND-58919 to O. Š. M.), and the University of Houston. K. V. K. thanks Deutsche Forschungsgemeinschaft (DFG) for funding under Germany’s Excellence Strategy – 2082/1 – 390761711. P. W. thanks the generous funding from the DFG Collaborative Centre SFB/TRR 88 “3MET” (Project C6). O. Š. M. thanks the Max Kade and Alexander von Humboldt Foundations for supporting his summer stay at the Ruprecht-Karls-Universität in Heidelberg (Germany), during which the collaboration that produced these results was initiated.