Substituted fluorenones

Early ESR studies demonstrated that the hyperfine coupling constant (ac 13) for 13C(car-bonyl)-substituted fluorenone radical anion is counterion-dependent. For the free ion, ac 13 = 2.75 Gauss. In contrast, when the counterion is Li+, ac 13 = 6.2 Gauss23. Consider Scheme 4 For the free ion, canonical structure 1 and 2 are contributors to the resonance hybrid. For the >C=0 / Li+ ion pair, association of Li+ with oxygen increases the relative contribution of canonical structure 1 to the resonance hybrid, resulting in greater spin density at carbon. The fact that spin (and charge density) varies as a function of counterion (and presumably solvent) will certainly affect the reactivity of the radical ion. However, very few quantitative studies exist which directly address this point. 

The products obtained from esters of anthranilic acid and substituted anthranilic acids are of interest because fluorenones can be prepared from them. From diazotized methyl anthranilate and benzene, 2-carbometh-oxybiphenyl is obtained in 24% yield. Hydrolysis affords 2-biphenylcar-boxylic acid, which can be cyclized to fluorenone. By this procedure, a number of 2- and 3-substituted fluorenones have been prepared.16 Thus, 3-chlorofluorenone was prepared from methyl 4-chloroanthranilate and benzene through the following steps. 

Ring closure of w s-o-aminostilbene (XIX) to phenanthrene, o-aminobi-benzyl (XX) to 9,10-dihydrophenanthrene, and o-aminodiphenylmeth-ane (XXI) to fluorene can be effected likewise through the diazoniflm reaction.26 A number of substituted fluorenones have been prepared by this method.26 ... 

Phenanthridone has been obtained from both fluorenone and its oxime by Schmidt and Beckmann procedures, respectively. Starting from unsymmetrically substituted fluorenones, mixtures of isomeric phenanthridones are frequently formed. 

Section 15.2 contains hydrocarbon and substituted hydrocarbon anion radicals. It is divided into two main parts Section 15.2.1 deals with hydrocarbon radical anions whilst Sect. 15.2.2 deals with substituted compounds and is subdivided into 3 subsections. Section 15.2.2.1 is concerned with the substituted radical anions, Sect. 15.2.2.2 deals with perfluoro and perchloro substituted radical anions, and Sect. 15.2.2.3 contains substituted fluorenones. These have been included for completeness and because we feel that they may not be included elsewhere. Mono-, di- and trianions are also included. 

The cationic rhodium(l)/axially chiral biaryl bisphosphine complex-catalyzed [2+2+2] cycloaddition of biaryl-linked tetraynes with dialkynylketones or dialkynylphosphine oxides afforded helically chiral l,l -bitriphenylenes, containing adensely substituted fluorenone or phosphafluorene core (Scheme 21.23) [27]. 

The rho values (2.78 overall, 3.78 for reduction to the cis product and 1.96 for reduction to the trans), determined from a study of the rates of reduction with NaBH4 of a series of 4-substituted cyclohexanones, have been interpreted as supporting a transition state late in the reaction.Other groups have observed positive rho values (2.5 to 3.1) for the reduction with NaBH4 of fluorenones and acetophenones. These results show clearly... 

The TCNQ molecule in [TR(bzim)]2-TCNQ is sandwiched between two units of [ J,-N, C -bzimAu]3 in a face-to-face manner so that it is best represented by the formula (7t-[ J,-N, C -bzimAu]3)( j,-TCNQ)(7t-[p-N, C -bzimAu]3). The cyanide groups clearly are not coordinated to the gold atoms. The distance between the centroid of TCNQ to the centroid of the AU3 unit is 3.964 A. The packing of [TR(bzim)]2-TCNQ shows a stacked linear-chain structure with a repeat pattern of-(Au3)(Au3)(p-TCNQ) (Au3)(Au3)(p-TCNQ)- an ABBABB repeat The complex [TR(bzim)]2-TCNQ contains two very short intermolecular Au Au distances of 3.152 A (identical for the two aurophilic bonds). The intermolecular Au Au distance is even shorter than the intramolecular distances in the starting compound, which are 3.475, 3.471, and 3.534 A. The adjacent AU3 units in [TR(bzim)]2-TCNQ form a chair-type structure rather than the face-to-face (nearly eclipsed) pattern reported in Balch s studies of the nitro-9-fluorenones adducts with the trinuclear Au(I) alkyl-substituted carbeniate complexes. 

Patents of Dow Chemicals first described 9,9-diaryl-substituted PF homopolymers 204 and 205 by Yamamoto polymerization of the corresponding 2,7-dibromo monomers [272], although the methods for monomer preparation were not described. For unsubstituted fluorenone, a convenient method for its conversion into 9,9-(4-hydroxyphenyl)-[307-309] and 9,9-(4-alkoxyphenyl)fluorenes [310] was reported previously, which included condensation of fluorenone with phenol or its ethers in acidic conditions (dry HC1 [308,309] or H2SO4 [307,311]) in the presence of (3-mcrcaptopropionic or mercaptoacetic acids. Both polymers 204 and 205 showed similar Mn 21,000 with PDI of 1.48 and 1.75, respectively, and spectral data typical for PF (205 Aabs = 389 (r 50,000 //(mol cm) APL = 417, 439, and 473 mn (THF)) (Chart 2.48). 

Polynitro-fluorenones 44 and 9-dicyanomethylenenitrofluorenes 45 (as acceptors) form molecular complexes with substituted anilines in various solvents146. The constant of... 

In case of fluorenone, the situation is reversed. A general bond-order increase is expected when an electron is added to a substituted cyclopentadienone such as fluorenone (Scheme 2.39). 

Similar surface-supported amides have been derived from the Sm" amide Sm N-(SiHMe)2 2(thf)x by grafting on MCM-41, MCM-48 or AS-200 further elaboration led to the formation of the corresponding Sm-fluorenone ketyl, which was shown to contain surface-confined ketyl radicals.Treatment of Sm N(SiHMe2)2 (thf)x MCM-41 with MeOH, AlHBu 2 or Si(H)Me2-substituted indene gave surface-supported catalysts for methyl methacrylate polymerisation. 

The Balz-Schiemann synthesis can be applied not only to substituted anilines but also to aminobiphcnyls1,131 or amino-substituted fused polyaromatic compounds, such as naphthalene,1114,119,129 anthracene,136 phenanthrene,1135 acenaphthene,133 fluorene,1,131,134 benzanthracene,130 136 pyrene,136 chrysene,136 fluoranthene,131 fluorenone,1,131 anthra-quinone,1,137,139,140 benzanthrone,1,117,118 phenanthraquinone,138 or xanthone.132 Fluorinated pyridines,1,141"146 methylpyridincs,126,147 149 pyridinecarboxylic acids,150 quinolines,1,151 isoquinolines,152 quinazolone,1 thiazoles,153,154 isothiazoles,156 benzothiazoles,157 thiadiazoles,155 and thiophenes154 can also be obtained from the corresponding aminated heterocycles. Modified Balz-Schiemann methods are recommended for amino nitrogen-containing heterocycles, the diazonium salts of which are rather water-soluble and unstable (a violent explosion was reported for pyridine-3-diazonium tetrafluoroborate).159 These new techniques have also been specially adapted for pyrazol-, imidazol-, or triazolamines which fail to react under classical conditions.158... 

Concerning electrophilic side reactions, intramolecular Friedel-Crafts condensations have been reported for example, fluorenone is formed from 2-benzoylbenzenediazonium tetrafluorobo-rate.241 The strong Lewis acid boron trifluoride can also be responsible for side reactions, such as the extensive formation of tars from nitro-substituted arenediazonium tetrafluorobor-ates or the acidic hydrolysis of ester substituents, especially in the case of 2-(ethoxycar-bonyl)benzenediazonium tetrafluoroborate.105,242... 

The expedient and regioselective metalation of unprotected biphenyl-2-, -3-, and -4-carboxylic acids has been reported.59 Unprotected biphenyl-2-carboxylic acid has been cleanly metalated with. sex-butyllithium at the position adjacent to the carboxylate and can then be subjected to site-selective electrophilic substitution (Scheme 8). The remote C(2 )-position has been attacked by the superbasic mixture of n-BuLi and t-BuOK (LICKOR) in THF or benzene. The resulting dianion cyclizes to give the fluorenone skeleton. The mechanism of the metalation of homologous compounds, 2-(pyridin-3-yl)benzoic acid derivatives, with strong bases has also been discussed.60... 

The quadrupole mass spectrometer which was used for these initial studies could provide only limited insight into the formation or structures of these unusual ions from fluorene and amino PAH. Experiments using substituted fluorenes, such as 1-, 2-, and 9-methylfluorene, 9-phenylfluorene, and carbazole, revealed that the (M + 14) ion did not form if the C-9 position was blocked. Knowing that the (M + 14) ion was formed by a reaction at the C-9 carbon, two possible structures could be drawn for this anion. One possibility would be 9-methylfluorene (structure I), which could arise from the addition of CH2 to fluorene. Similar formation of adducts from methane buffer gas under NICI conditions has been reported (7, 8). Alternatively, fluorene could lose the two hydrogens at the 9-position and add oxygen to form 9-fluorenone (structure II)... 

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