84941-00-4Relevant articles and documents
Synthesis of a Strained Spherical Carbon Nanocage by Regioselective Alkyne Cyclotrimerization
Hayase, Norihiko,Nogami, Juntaro,Shibata, Yu,Tanaka, Ken
supporting information, p. 9439 - 9442 (2019/06/24)
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.
METHOD FOR PRODUCING BENZENE COMPOUND AND CATALYST FOR PRODUCING BENZENE COMPOUND
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Paragraph 0028, (2019/03/02)
PROBLEM TO BE SOLVED: To provide a method for producing a benzene compound capable of performing production of various benzene compounds with low environmental load without generating waste as in the case of using benzene as a starting raw material and to provide a catalyst used for the production method. SOLUTION: There are provided: a method for producing a benzene compound from alkynes in the presence of a catalyst, wherein the catalyst is a PdAu supported catalyst obtained by supporting Pd and Au in a molar ratio of 1:1 to 1:10 on a carrier; and a catalyst used for the production method. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPOandINPIT
Divergent reactivity of a new dinuclear xanthene-bridged bis(iminopyridine) di-nickel complex with alkynes
Hollingsworth, Ryan L.,Bheemaraju, Amarnath,Lenca, Nicole,Lord, Richard L.,Groysman, Stanislav
, p. 5605 - 5616 (2017/07/10)
The reaction of a dinucleating bis(iminopyridine) ligand L bearing a xanthene linker (L = N,N′-(2,7-di-tert-butyl-9,9-dimethyl-9H-xanthene-4,5-diyl)bis(1-(pyridin-2-yl)methanimine)) with Ni2(COD)2(DPA) (COD = cyclooctadiene, DPA = diphenylacetylene) leads to the formation of a new dinuclear complex Ni2(L)(DPA). Ni2(L)(DPA) can also be obtained in a one-pot reaction involving Ni(COD)2, DPA and L. The X-ray structure of Ni2(L)(DPA) reveals two square-planar Ni centers bridged by a DPA ligand. DFT calculations suggest that this species features NiI centers antiferromagnetically coupled to each other and their iminopyridine ligand radicals. Treatment of Ni2(L)(DPA) with one equivalent of ethyl propiolate (HCCCO2Et) forms the Ni2(L)(HCCCO2Et) complex. Addition of the second equivalent of ethyl propiolate leads to the observation of cyclotrimerised products by 1H NMR spectroscopy. Carrying out the reaction under catalytic conditions (1 mol% of Ni2(L)(DPA), 24 h, room temperature) transforms 89% of the substrate, forming primarily benzene products (triethyl benzene-1,2,4-tricarboxylate and triethyl benzene-1,3,5-tricarboxylate) in 68% yield, in a ca. 5:1 relative ratio. Increasing catalyst loading to 5 mol% leads to the full conversion of ethyl propiolate to benzene products; no cyclotetramerisation products were observed. In contrast, the reaction is significantly more sluggish with methyl propargyl ether. Using 1 mol% of the catalyst, only 25% conversion of methyl propargyl ether was observed within 24 h at room temperature. Furthermore, methyl propargyl ether demonstrates the formation of cyclooctatetraenes in significant amounts at a low catalyst concentration, whereas a higher catalyst concentration (5 mol%) leads to benzene products exclusively. Density functional theory was used to provide insight into the reaction mechanism, including structures of putative dinuclear metallocyclopentadiene and metallocycloheptatriene intermediates.
