フッ素置換錯体を基盤とする有機フッ素化合物の触媒的合成法

科学研究費助成事業 研究成果報告書：基盤研究(C)2015-2017課題番号 : 15K0541

Catalytic Synthesis of Organofluorine Compounds Based on Difluorocarbene Complexes

科学研究費助成事業(科学研究費補助金)研究成果報告書：挑戦的萌芽研究2010-2011課題番号：2265501

Synthesis of Pinpoint-Fluorinated Polycyclic Aromatic Hydrocarbons: Benzene Ring Extension Cycle Involving Microwave-Assisted SNAr Reaction

Fluoroarenes bearingnoelectron-withdrawing groups (non-activated fluoroarenes) readily underwent nu-cleophilic aromatic substitution with a-cyanocarbanions under microwave irradiation. The sequence (i)formylalkyla-tion involving the cyanoalkylation of fluoroarenes, (ii)di-fluorovinylidenati on, and (iii)Friedel–Crafts-typecycliza-tion, afforded extended fluoroarenes by one benzene ring per cycle. Furthermore, the performance of multiple cyclessuccessfully providedhigher-order pinpoint-fluorinated polycyclic aromatic hydrocarbons (F-PAHs)

Single C−F Bond Activation of the CF3 Group with a Lewis Acid: CF3‐Cyclopropanes as Versatile 4,4‐Difluorohomoallylating Agents

The selective activation of one C−F bond (single activation) of the CF3 group on cyclopropanes was achieved for the first time. When (trifluoromethyl)cyclopropanes were treated with arenes, allylsilanes, silyl enol ethers, or hydrosilanes in the presence of Me2AlCl, fluoride elimination and the subsequent ring opening proceeded to afford 4,4‐difluorohomoallylated products. In the absence of external nucleophiles, an alkyl group of AlR3 was effectively introduced to provide the corresponding 1,1‐difluoroalkenes

Synthesis of (difluoromethyl)naphthalenes using the ring construction strategy: C–C bond formation on the central carbon of 1,1-difluoroallenes via Pd-catalyzed insertion

The insertion of 1,1-difluoroallenes was carried out to form a C–C bond exclusively on their central carbon. o-Bromophenyl-bearing 1,1-difluoroallenes underwent intramolecular insertion in the presence of a palladium catalyst. Regioselective C–C bond formation occurred to form a six-membered carbocycle, leading to pharmaceutically and agrochemically promising difluoromethylated naphthalenes

Pinpoint-fluorinated polycyclic aromatic hydrocarbons (F-PAHs): Syntheses of difluorinated subfamily and their properties

Difluorinated polycyclic aromatic hydrocarbons (PAHs) containing three to five benzene rings were systematically synthesized by the Pd(II)-catalyzed Friedel–Crafts-type cyclization of 1,1,2-trifluoro- and 1,1-difluoro-1-alkenes and the In(III)-catalyzed tandem cyclization of bis(1,1-difluoroallene)s. Using an array of the difluorinated PAHs that were obtained and previously reported monofluorinated PAHs, the physical properties of the pinpoint-fluorinated PAHs were investigated. (i) The 19F NMR signals of the bay-region fluorine atoms were shifted downfield by ca. 8–14 ppm for vic-difluorinated PAHs and ca. 11–19 ppm for non-vic-difluorinated and monofluorinated PAHs. (ii) The introduction of fluorine into PAH molecules increased their solubilities in organic solvents, which was best exemplified by the high solubilities of 6,7-difluoropicene (5.4 wt%) and 6-fluoropicene (5.3 wt%) in THF. (iii) The HOMO–LUMO energy gaps of the pinpoint-fluorinated PAHs were smaller than that of the corresponding fluorine-free PAH (i.e., picene) by 0.02–0.26 eV, and the HOMO and LUMO energy levels were lowered by 0.10–0.22 eV and 0.12–0.41 eV, respectively

Facile Synthesis of Polycyclic Aromatic Hydrocarbons: Brønsted Acid Catalyzed Dehydrative Cycloaromatization of Carbonyl Compounds in 1,1,1,3,3,3-Hexafluoropropan-2-ol

The cycloaromatization of aromatic aldehydes and ketones was readily achieved by using a Brønsted acid catalyst in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP). In the presence of a catalytic amount of trifluoromethanesulfonic acid, biaryl-2-ylacetaldehydes and 2-benzylbenzaldehydes underwent sequential intramolecular cationic cyclization and dehydration to afford phenacenes and acenes, respectively. Furthermore, biaryl-2-ylacetaldehydes bearing a cyclopentene moiety at the α-position underwent unprecedented cycloaromatization including ring expansion to afford triphenylenes. HFIP effectively promoted the cyclizations by suppressing side reactions presumably as a result of stabilization of the cationic intermediates