Anthracenes intramolecular

Cyclopenta[fc]dioxanes (44) are accessible from the reaction of the dioxenylmolybdenum carbene complex (43) with enynes <96JOC159>, whilst an intramolecular and stereoselective cyclisation of (Ti5-dienyl)tricarbonyliron(l+) cations affords chiral frans-2,3-disubstituted 1,4-dioxanes <96JOC1914>. 2,3-Dimethylidene-2,3-dihydro-1,4-benzodioxin is a precursor of the 3,8-dioxa-lff-cyclopropa[i]anthracene, which readily dimerises to dihydrotetraoxaheptacene (45) and the analogous heptaphene <96AJC533>. 

Flegel, M. Lukeman, M. Huck, L. Wan, P. Photoaddition of water and alcohols to the anthracene moiety of 9-(2 -hydroxyphenyl)anthracene via formal excited state intramolecular proton transfer. J. Am. Chem. Soc. 2004, 126, 7890-7897. 

Basaric, N. Wan, P. Competing excited state intramolecular proton transfer pathways from phenol to anthracene moieties. J. Org. Chem. 2006, 71, 2677-2686. 

Similar formations of bisanthracenes have been studied with a variety of substituents. An interesting example of a cation-assisted intramolecular anthracene dimerization where the bisanthracene formation includes cycli-zation of a polyether chain to a crown ether is illustrated in (4.27). In the absence of Li+ the dimer reverts back to the open chein compound, but in the presence of Li+ the crown ether is stabilized so that the product itself also becomes more stable 430). 

Schwarzer D, Kutne P, Schroder C, Troe J (2004) Intramolecular vibrational energy redistribution in bridged azulene-anthracene compounds ballistic energy transport through molecular chains. J Chem Phys 121 1754... 

Intramolecular charge transfer in p-anthracene-(CH2)3-p-Ar,Af-dimethylaniline (61) has been observed174 in non-polar solvents. Measurements of fluorescence-decay (by the picosecond laser method) allow some conclusions about charge-transfer dynamics in solution internal rotation is required to reach a favourable geometry for the formation of intramolecular charge-transfer between the donor (aniline) and the acceptor (anthracene). 

A new type of photodissociation for p-nitrobenzyl 9,10-dimethoxyanthracene-2-sulphonate 164 has been reported to give 9,10-dimethoxy-anthracene-2-sulphonic acid 165, 9,10-dimethoxy-2-(p-nitrobenzyl)-anthracene 166 and p,p -dinitrobibenzyl101 (equation 81). It is suggested to occur from excited intramolecular electron transfer followed by radical ion decompositions and recombinations. 

F. Pages, J.-P. Desvergne, and H. Bouas-Laurent, Nonlinear triple exciplexes Thermodynamic and kinetic aspects of the intramolecular exciplex formation between anthracene and the two anchored nitrogens of an anthraceno-cryptand, /. Am, Chem. Soc. Ill, 96-102(1989). 

The autoxidation mechanism by which 9,10-dihydroanthra-cene is converted to anthraquinone and anthracene in a basic medium was studied. Pyridine was the solvent, and benzyl-trimethylammonium hydroxide was the catalyst. The effects of temperature, base concentration, solvent system, and oxygen concentration were determined. A carbanion-initi-ated free-radical chain mechanism that involves a singleelectron transfer from the carbanion to oxygen is outlined. An intramolecular hydrogen abstraction step is proposed that appears to be more consistent with experimental observations than previously reported mechanisms that had postulated anthrone as an intermediate in the oxidation. Oxidations of several other compounds that are structurally related to 9,10-dihydroanthracene are also reported. 

This study indicates that the oxidation of dihydroanthracene in a basic medium involves the formation of a monocarbanion, which is then converted to a free radical by a one-electron transfer step. It is postulated that the free radical reacts with oxygen to form a peroxy free radical, which then attacks a hydrogen atom at the 10-position by an intramolecular reaction. The reaction then proceeds by a free-radical chain mechanism. This mechanism has been used as a basis for optimizing the yield of anthraquinone and minimizing the formation of anthracene. 

Scheme 20 Inter-intramolecular Heck coupling sequences with cyclizations leading to a macrocycle and to 9,10-dihydro-anthracene derivatives. " ...

Subsequent one-electron transfer and intramolecular hydrogen migration lead to radical 102 followed by reaction with 02 to yield hydroperoxide radical 103. Radical 103 is further oxidized to a dihydroperoxide (104), which decomposes to anthra-quinone. Alternatively, 103 may be transformed to a diradical that eventually gives anthracene as a byproduct. The ratio of the two products strongly depends on the solvent used. The highest yield of anthraquinone (85% at 100% conversion) was achieved in 95% aqueous pyridine. 

A polymer containing anthracene, [Ru(bpy)3]2 , and [Os(bpy)3]2+ [all covalently linked to a 1 1 copolymer of styrene and m,p-(chlorome-thyl)styrene] has been prepared, and its emission spectrum and intramolecular electron-transfer properties have been studied (569). 

Rhodium(II) acetate catalyzes C—H insertion, olefin addition, heteroatom-H insertion, and ylide formation of a-diazocarbonyls via a rhodium carbenoid species (144—147). Intramolecular cyclopentane formation via C—H insertion occurs with retention of stereochemistry (143). Chiral rhodium (TT) carboxamides catalyze enantioselective cyclopropanation and intramolecular C—N insertions of CC-diazoketones (148). Other reactions catalyzed by rhodium complexes include double-bond migration (140), hydrogenation of aromatic aldehydes and ketones to hydrocarbons (150), homologation of esters (151), carbonylation of formaldehyde (152) and amines (140), reductive carbonylation of dimethyl ether or methyl acetate to 1,1-diacetoxy ethane (153), decarbonylation of aldehydes (140), water gas shift reaction (69,154), C—C skeletal rearrangements (132,140), oxidation of olefins to ketones (155) and aldehydes (156), and oxidation of substituted anthracenes to anthraquinones (157). Rhodium-catalyzed hydrosilation of olefins, alkynes, carbonyls, alcohols, and imines is facile and may also be accomplished enantioselectively (140). Rhodium complexes are moderately active alkene and alkyne polymerization catalysts (140). In some cases polymer-supported versions of homogeneous rhodium catalysts have improved activity, compared to their homogenous counterparts. This is the case for the conversion of alkenes direcdy to alcohols under oxo conditions by rhodium—amine polymer catalysts... 

The present contribution deals mainly with novel 9-substituted anthracenes in which the substituent either incorporates or by itself represents a 7r-system, and whose effect on the overall molecular shape is such as to have major photochemical and photophysical repercussions [33]. Not discussed are anthracenophanes [34] and various types of bichromophoric anthracenes whose excited state properties have been reviewed previously [8,25,35]. Considered beyond the scope of this contribution are the photochemistry and photophysics of anthraceno crown ethers and cryptands [36-38], and of intramolecular exciplexes derived from anthracenes linked to aromatic amines [39-41],... 

Photochemical isomerizations by intramolecular 4n + An cycloaddition of carbon oxygen linked bichromophoric anthracenes to give oxetane derivatives have not been reported yet. Upon irradiation (X > 400 nm) in either toluene or ethyl acetate, the methoxycarbonyl substituted carbon oxygen linked bichromophoric anthracene 14 indeed isomerizes smoothly and efficiently (cp — 0.45). However, the two products, obtained in an approximate ratio of 5 1, are anthrone derivatives 15 and 16 whose formation can be rationalized by migration of the anthryloxy moiety [60], An analogous photolytic rearrangement has been found for 9-anthryloxy substituted dianthrylethylenes (see Section III.A). 

Among the 1,3-linked bichromophoric anthracenes listed in Table 3, 1,3-di-9-anthryl-l-propanone 21a, l,3-di-9-anthryl-l-butanone 21b, and l,3-di-9-anthryl-2-methyl-l-propanone 21c are exceptional because their photochemical isomerization by intramolecular 4n+4n cycloaddition to give 22 is characterized by high quantum yields, viz. 0.65, 0.40, and 0.72, respectively. For photochemical cycloadditions of linked anthracenes, the quantum yield of 0.72 is the highest ever observed. Oxygen quenching and sensitization experiments indicate that 21a, 21b, and 21c undergo the 4n+4n cycloaddition in the excited triplet state (see Section II.C). 

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