Synthesis of a Strained Spherical Carbon Nanocage by Regioselective Alkyne Cyclotrimerization. Issue 28 (6th June 2019)

• Record Type: Journal Article
• Authors: Hayase, Norihiko; Nogami, Juntaro; Shibata, Yu; Tanaka, Ken
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 28(2019)
• Page Start: 9439
• Page End: 9442
• Publication Date: 2019-06-06
• Subjects: alkyne cyclotrimerization -- carbon nanocages -- molecular strain -- reductive aromatization -- rhodium; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201903422
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The smallest spherical carbon nanocage so far, [2.2.2]carbon nanocage, has been synthesized by the cationic rhodium(I)/H8 ‐binap complex‐catalyzed regioselective intermolecular cyclotrimerization of a cis ‐1‐ethynyl‐4‐arylcyclohexadiene derivative followed by the triple Suzuki–Miyaura cross‐couplings with 1, 3, 5‐triborylbenzene and reductive aromatization. This cage molecule is highly strained, and its ring strain is between those of [6] and [5]cycloparaphenylenes. A significant red‐shift of an emission maximum was observed, compared with that of known [4.4.4]carbon nanocage. The sequential cyclotrimerizations of a cis ‐1, 4‐diethynylcyclohexadiene derivative with the same rhodium(I) catalyst followed by reductive aromatization failed to afford [1.1.1]carbon nanocage; instead, a β‐graph‐shaped cage molecule was generated. Abstract : The smallest spherical carbon nanocage ([2.2.2]carbon nanocage) so far has been synthesized by the cationic rhodium(I)/H8 ‐binap complex‐catalyzed regioselective intermolecular homo‐cyclotrimerization of a cis ‐1‐ethynyl‐4‐bromophenyl‐cyclohexadiene derivative, followed by the triple Suzuki–Miyaura cross‐couplings with 1, 3, 5‐triborylbenzene and reductive aromatization.