Site-selective and direct C–F bond transformation of perfluoroalkylarenes was achieved with allylic stannanes via an iridium photoredox catalyst system. The present defluoroallylation proceeds ...exclusively at the benzylic position through perfluoroalkyl radicals generated by a single-electron transfer from an excited photoredox catalyst to perfluoroalkylarenes. A variety of perfluoroalkyl groups are applicable: linear perfluoroalkyl-substituted arenes such as Ar– n C4F9 and Ar– n C6F13 and heptafluoroisopropylarenes (Ar–CF(CF3)2) underwent site-selective defluoroallylation. DFT calculation studies revealed that the in situ generated Bu3SnF traps F– to prevent a retroreaction from the unstable perfluoroalkyl radical intermediate, and the radical intermediate favorably reacts with allylic stannanes. The synthesis of a bis(trifluoromethyl)methylene unit containing compound, which is an analog that is useful as a pharmaceutical agent for the prophylaxis or treatment of diabetes and inflammatory diseases, demonstrated the utility of this reaction.
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A nonbenzenoid hydrocarbon, difluoreno1,9,8-alkj:1′,9′,8′-gfedheptalene 1, is synthesized. Experimental and theoretical investigations demonstrate that the planar and symmetric heptalene core ...within 1 effectively induces the antiaromatic and open-shell character. These properties are not shared by bisanthene 2, a benzenoid isomer of 1.
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Organogallium and ‐indium compounds are useful reagents in organic synthesis because of their moderate stability, efficient reactivity and high chemoselectivity. Carbogallation and ‐indation of a ...carbon‐carbon multiple bond achieves the simultaneous formation of carbon‐carbon and carbon‐metal bonds. Heterogallation and ‐indation construct carbon‐heteroatom and carbon‐metal bonds. Therefore, these reaction systems represent a significant synthetic method for organogalliums and ‐indiums. Many chemists have attempted to apply various types of unsaturated compounds such as alkynes, alkenes, and allenes to these reaction systems. This minireview provides an overview of carboindation and ‐gallation as well as heteroindation and ‐gallation.
Organogallium and ‐indium compounds are useful reagents in organic synthesis due their moderate stability. Carbogallation and ‐indation of carbon‐carbon multiple‐bonds achieves simultaneous formation of carbon‐carbon and carbon‐metal bonds. And, heterogallation and ‐indation are used to construct carbon‐heteroatom and carbon‐metal bonds. So, these reaction systems represent significant synthetic methods for the use of organogalliums and ‐indiums. Various unsaturated compounds, such as alkynes, alkenes, and allenes are applicable to these reaction systems to access to organogalliums and ‐indiums with diverse functionalities.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
In the heterodifunctionalization of alkenes, 1,1-regioselectivity remains elusive in sharp contrast to 1,2-regioselectivity. Herein, the 1-fluoro-1-sulfonyloxylation of styrenes with Bu4NBF4 and ...sulfonic acids using a hypervalent iodine ArI(OAc)2 is reported. Regression analysis of substituents on ArI(OAc)2 suggested that their electron-withdrawing ability and steric factor influence the 1,1-heterodifunctionalization. We designed o-{2,4-(CF3)2C6H3}- and p-NO2-substituted ArI(OAc)2 by the regression analysis to achieve high selectivity.
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The oxyindation of carbonyl-ene-yne compounds with indium trihalides proceeded efficiently to give di-, tri-, and tetrasubstituted 2-pyrones bearing a carbon–indium bond. The metalated 2-pyrone and a ...zwitterion intermediate were identified by X-ray crystallographic analysis. The application of organoindium compounds to oxidation or cross-coupling provided easy access to various multifunctionalized 2-pyrones. Some 2-pyrone derivatives show intense fluorescence only in the solid state (aggregation-induced emission).
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The chemistry of nonalternant hydrocarbons has recently experienced a considerable resurgence. As the relationship between naphthalene and azulene shows, an important design concept for a ...nonalternant framework is to replace the two hexagons of an alternant system with a pentagon and heptagon pair. The pursuit of the nonalternant isomers of pyrene, which has seven possible nonalternant isomers, has been the most significant related project. Through enormous dedication by many pioneering works, six of the seven possible nonalternant isomers of pyrene have been isolated and characterized as stable aromatic molecules, differentiating themselves from pyrene in terms of optoelectronic properties. However, the only unsynthesized isomer, bis‐periazulene (cycloheptadeffluorene), had remained an uncharacterized hydrocarbon until 2022, despite many synthetic and theoretical investigations since it was first reported in 1955. In this review, we summarize the chemistry of the pyrene's nonalternant isomers, including our recent achievements in synthesizing and characterizing bis‐periazulene derivatives. The historical perspectives, synthetic approaches, fundamental properties, and comparisons to related systems are documented.
Since it was first reported in 1955, bis‐periazulene had remained an uncharacterized hydrocarbon until 2022. In this review, the chemistry of the pyrene's nonalternant isomers, which has a long history of investigation, is documented and recent achievements in synthesizing and characterizing bis‐periazulene derivatives are described.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Bis-periazulene (cyclohepta
fluorene) is one of the seven possible non-alternant isomers of pyrene. Different from the other isomers, bis-periazulene had remained an uncharacterized hydrocarbon until ...2022, since it was first reported in 1955. This paper documents our recent achievements in synthesizing and characterizing bis-periazulene derivatives. Its triaryl derivatives
exhibited the superimposed electronic structures of peripheral, polarized, and open-shell π-conjugated systems. Furthermore, in contrast to previous theoretical predictions, bis-periazulene derivatives showed the singlet ground state.
Mesityl derivatives of the unknown dibenzopentalene isomer dibenzoa,fpentalene were synthesized. The molecular geometry and physical properties of dibenzoa,fpentalene were investigated. ...Dibenzoa,fpentalene combines a large antiaromatic and appreciable singlet open-shell character, properties not shared by well-known isomer dibenzoa,epentalene.
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The Tsallis entropy is a
q
-parameter extension of the Shannon entropy. By maximizing it within the framework of fuzzy
c
-means, statistical mechanical membership functions can be derived. We propose ...a clustering algorithm that includes the membership function and deterministic annealing. One of the major issues for this method is the determination of an appropriate values for
q
and an initial annealing temperature for a given data distribution. Accordingly, in our previous study, we investigated the relationship between
q
and the annealing temperature. We quantitatively compared the area of the membership function for various values of
q
and for various temperatures. The results showed that the effect of
q
on the area was nearly the inverse of that of the temperature. In this paper, we analytically investigate this relationship by directly integrating the membership function, and the inversely proportional relationship between
q
and the temperature is approximately confirmed. Based on this relationship, a
q
-incrementation deterministic annealing fuzzy
c
-means (FCM) algorithm is developed. Experiments are performed, and it is confirmed that the algorithm works properly. However, it is also confirmed that differences in the shape of the membership function of the annealing method and that of the
q
-incrementation method are remained.
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