Azulene aldehydes

The reactivity of these methyl groups is normally enhanced by nitrogen atom quaternization. Benzotroponopyridinium salt 505 with two molecules of azulene aldehyde condenses to afford blue-black bis(azulenylvinyl) dye 506 (Amax 536 nm 62ZC369). Furthermore, oxazolium salt 507 condenses with activated benzothiazolium salt 508 (Scheme 134) to form unsymmetri-cal trimethine cyanine 509 (63UP1). (Dyes 512a,b arise from methylthio exchange Section IV,A,5,e.)... 

By using triisobutyl- and diisobutylalane such reductions may be extended to other aldehydes and ketones 206). Some benzaldehyde derivatives, furfural, and some azulene aldehydes are reduced without the occurrence... 

The condensation of a vinylogous formamide with an enamine has been applied to an aza azulene synthesis (351). The point of attachment of the aldehyde to the enamine in condensations with indolenin derived poly-enamines was found to favor the second double bond (352,353). 

Kurz darauf beschrieben H. Arnold und K. PaHls (8) die Reduktion von 4,8-Dimethyl-azulen-6-carbonsaure-athylester bei —60° mit dem gleichen Reduktionsmittel zu dem entsprechenden primaren Alkohol [66], der fiber das Azulenpyridinium-tosylat und Nitron in den 4,8-Dimethyl azulenaldehyd- (6) [77] iibergefiihrt wurde. Dieser erste synthetische Azulenaldehyd ist im Zusammenhang mit dem Lactaroviolin, einem von H. Willstaedt (184) aus dem echten Reizker isolierten Aldehyd von Interesse. 

Wittig reactions with pyrrole-2-aldehyde led to the esters (79) which were cyclisized to 3a-azaazulen-4-ones (80).104,105 4-Methylene-3a-aza-azulenes (81) have been obtained from 80 with stabilized phos-phoranes.36 Reaction of dimethyl acetylenedicarboxylate with 81 could not be achieved. A similar cycloaddition was successful in the synthesis of cycl[3,3,3]azines (2) (Section V). 

The pKa values given for diphenylcyclopropenone, tropone and azulene-l-aldehyde were obtained by spectrophotometric titration with aqueous acids in the author s laboratory these figures are accurate to 0.3 pK units. The dipole moment of perinaphthenone in benzene was measured by R. J. Best and K. Mead of the Stamford laboratories of the American Cyanamid Co., Connecticut, U.S.A. 

Photocleavage of benzyl-S bonds appears to proceed neither by an electron transfer pathway nor with participation of an exciplex. A meta effect seems to operate in these reactions as evidenced by the influence of 3-methoxy and of 3-cyano substituents on the efficiency of the cleavage process. Photolysis of 1,2-bis(phenoxymethyl)-, l,2-bis(phenylthiomethyl)-, and l,2-bis(phenylseleno-methyl)benzene induces a two-photon process to give o-quinonedimethane, which in the presence of dienophiles undergoes a cycloaddition reaction, and 4,8,10-trithiadibenzo[cd,ij]azulene 8-oxides gives the corresponding aldehydes and ketones together with 4,8,9-trithiacyclopenta[def]phenanthrene. The two... 

Rigby synthesized a [5.3.1] oxa-bridged nucleus in the context of a perhydro-azulene synthesis [89]. Upon treatment of 81 with BF3 etherate, a hetero-Diels-Alder reaction between the aldehyde and the diene occurred to give 82 in good yield, Eq. 62. 

Nonbenzenoid carbocyclic compounds also participate in the Vilsmeier-Haack reaction yielding aldehyde derivatives. Examples include azulene and the cyclopentadienyl anion. ... 

There are general reviews on heterocyclic syntheses by cycloaddition reactions of isocyanates and on the use of heterocyclic cations in preparative organic chemistry. More specific topics are 5-hydroxymethylfuran-2-carb-aldehyde, isobenzofurans and related ort/io-quinonoid systems, the conversion of 2//-cyclohepta[Zj] furan-2-one (1) into derivatives of azulene, the synthesis of indoles from o-alkylphenyl isocyanides, and abnormal Fischer indolization reactions of o-methoxyphenylhydrazones. Two reviews on isoindoles have appeared and a lecture on highly conducting charge-transfer complexes that are based on heterocyclic selenium and tellurium donors has been reprinted.Recent advances in the chemistry of imidazole and in the use of nitro-imidazoles as radiosensitizers have been summarized. There have been reviews on benzimidazole A -oxides and on dihydrobenzimidazoles, benzimidazolones, benzimidazolethiones, and related compounds. Other topics are synthetic applications of 1,3-dithiolium and 1,3-oxathiolium salts and of isoxazoles, the chemistry of benzisoxazoles, 2-amino-oxazoles, 5-oxazolones (2), furoxans, benzofuroxans, and related systems, the synthesis of five-membered meso-ionic compounds, and tetrazoles. ... 

Fovmlation can be carried out by means of the Gattermann reaction [98] or the Vilsmeier reaction [121 - 123], or by using ethyl orthoformate in the presence of a Friedel-Crafts catalyst [124]. In each case the 1-aldehyde is obtained. Azulene-l-aldehyde is less reactive than benzene aldehydes towards nucleophiles, presumably because any charge developed on the carbonyl carbon atom can be delocalised into the seven-membered ring [111,125 - 127]. 

Azulenes undergo condensation reaations with aryl and heteroaryl aldehydes in the presence of mineral acids to give azulenium salts, which can react with nucleophiles to give a variety of 1-substituted derivatives, e.g. [82,125,128,129]. 

By replacing 105 with aromatic aldehydes 69 in this three-component domino reaction, a total of 38 examples of benzo[f]azulen-l-ones 164 in good overall yields (70-89%) have been synthesized with high regioselectivity (Scheme 12.66) [90]. 

C02Me, etc.) have been prepared by bis-condensations between the appropriate pyrrole bis-aldehyde and substituted acetone l,3-dimethyl-2/f-cyclohepta[c]pyrrol-6-one (148 R = H, R = R = Me, X = H) was then converted into 6-ethoxy-l,3-dimethyl-2-aza-azulene, ... 

Monoiodo, dibromo, trichloro, and 300 Benzyl chloride Azulene Cinnam aldehyde... 

Wang and coworkers have reported a microwave-assisted MCR in water for the synthesis of benzo[/]azulen-1-ones [96]. The reaction of benzene-l,2-diamines 130, tetronic acid 131, and aldehydes 51 in aqueous phase under... 

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