Debenz[c,j]octalen

Dibenzo[c,j]octalene (2), to be regarded as a model for the hypothetical octalene double bond isomer (1), has been synthesized. As borne out by NMR studies, (2) exists as an equilibrating mixture of the anticipated conformers (2a) and 2(b).     

Hydrierte Derivate von Benz[f]- und Benz[g]isochinolinen

Zusammenfassung Aus 1- und 2-(2-Aminoalkyl)-5,6,7,8-tetrahydronaphthalin wurden durch Ringschluß nachPictet—Spengler oderBischler—Napieralski hydrierte Benz[f]- und Benz[g]isochinoline gewonnen. Einzelne dieser Verbindungen zeigen beachtliche analgetische Wirkung.

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From 1- and 2-(2-aminoalkyl)-5,6,7,8-tetrahydronaphthalene, hydrogenated benz[f]- and benz[g]isoquinolines have been obtained by cyclization according toPictet—Spengler orBischler—Napieralski. Some of these compounds exhibit remarkable analgesic activity.

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Herrn Prof. Dr.H. Bretschneider zu seinem 60. Geburtstag gewidmet.     

Benz[c,d]indoles - II. synthesis by the saegusa cyclization

A convenient synthesis of substituted benz[c,d]indoles is described. The method consists in cyclization of bicyclic isonitriles with strong bases such as LDA to the corresponding tricyclic compound.     

An Efficient Straightforward Synthesis of Benz[a]azulene

Benz[a]azulene ( 1 ) is synthesized in five steps (cf. Scheme 2) starting from commercially available 2-iodobenzyl alcohol ( 4 ) and tropylium tetrafluoroborate in an overall yield of 44%. The key step (cf. also Scheme 1) is the intramolecular Heck reaction of the 8-phenylsulfonyl-substituted heptafulvene 7 , which leads in nearly quantitative yield directly to 10-(phenylsulfonyl)benz[a]azulene ( 8 ). The desulfonylation of 8 can be accomplished by Julia's method with Na₂S₂O₄/NaHCO₃ in DMF/H₂O at 85–90°, thus leading to pure 1 in 78% yield. The phenylation of 8 with PhLi or PhCul at ?78° in THF occurs regioselectively at C(9). Dehydrogenation of the formed dihydroazulenes with o-chloroanil in toluene at room temperature gives 9-phenyl-10-(phenylsulfonyl)-benz[a]azulene ( 9 ) in 70% yield (cf. Scheme 3), which, again, can be desulfonylated with Na₂S₂O₄/NaHCO₃ in DMF/H₂O in good yields. The addition of PhLi to 1 in THF occurs at temperatures ? ?25°. Ionic dehydrogenation (1. Ph₃C⁺BF/MeCN; 2. Et₃N) of the dihydro forms leads to 3 , as the main product, and its positional isomers.     

Synthesis of Benz[a]azulenes Substituted at the Benzo Ring

It is shown that the thermal electrocyclic ring-closure reaction of 1,2-di[(E)-prop-1-enyl]benzene to yield 2,3-dimethylnaphthalene (cf. Scheme 1) [10] can successfully be applied also to the synthesis of benz[a]azulenes (cf. Schemes 2 and 3). Starting materials are methyl 4,6,8-trimethylazulen-2-yl ketone ( 6 ) and the corresponding 2-carbaldehyde 5 , which, in a Horner-Emmons reaction, are transformed into the (azulen-2-yl)-acrylates (E)- 8 and (E)- 7 , respectively. Vilsmeier formylation of these compounds, followed by the Horner-Emmons reaction leads to the formation of the bisacrylates (E,E)- 11 and (E,E)- 12 , respectively. In an alternative reaction, (E)- 8 , on treatment with dimethyl acetylenedicarboxylate (ADM) in the presence of [RuH₂(PPh₃)₄], can be transformed into the methoxycarbonyl-substituted bisacrylates (E,E)- and (E,Z)- 17 . All three bisacrylates, on heating at 180–190° in p-cymene, undergo cyclization to yield the corresponding dihydrobenz[a]azulenes 13 , 14 , and 18 , respectively, which could easily be dehydrogenated on heating in the presence of Pd/C. The new benz[a]azulenes 15 , 16 , and 19 are fully characterized.     

Synthesis of 6-fluoroalkylbenzo[h]cyclopenta[c]quinoline and -benzo[c]phenanthridine derivatives

Russian Chemical Bulletin -     

Cyclopenta[c]pyrans

Natural occurrence, synthesis, chemical behavior, and physical properties of aromatic cyclopenta[c]pyrans are reviewed. Various strategies for the synthesis of cyclopenta[c]pyrans starting from cyclopentadienes, fulvenes, oxadiazinones, or α‐pyrones were developed according to the substitution patterns of the target compounds. J. Heterocyclic Chem., (2011).     

Benz[c,d]indoles - I. The use of tert-butoxy-bis(dimethylamino)methane as condensation reagent.

A simple and efficient route to benz[c,d]indoles is the reaction of nitrotetralins with Bredereck's reagent and reduction of the condensation product to the corresponding annelated indole.     

Azulene–Naphthalene‐Type Rearrangements in Benz[a]azulene and Cyclohepta[b]indole

Flash vacuum pyrolysis (FVP) of benz[a]azulene yields phenanthrene and 2‐ethynylbiphenyl. FVP of cyclohepta[b]indole similarly yields phenanthridine and 2‐cyanobiphenyl. The reversibility of the reactions is demonstrated by FVP of 2‐ethynylbiphenyl and 2‐isocyanobiphenyl. All the observed reactions are in accord with the norcaradiene–vinylidene mechanism of the azulene–naphthalene rearrangement, whereas other proposed mechanisms are ruled out.     

Synthesis of Benz[1,2-a]aceanthrylene from Triptycene via Flash Vacuum Thermolysis

Benz[1,2-a]aceanthrylene is prepared from triptycene in 60 % yield by flash vacuum thermolysis at 875° C.     

Preparation of Benz[b]Indeno[1,2-e]Pyran-11(6H)-Ones and Benz[b]Indeno[1,2-e]Thiopyran-11(6H)-One from Dilithiated 2-Indanone and Lithiated Methyl Salicylates or Lithiated Methyl Thiosalicylate

Dilithiated 2-indanone was prepared with excess lithium diisopropylamide, and the resulting intermediate was condensed with several lithiated methyl salicylates or lithiated methyl thiosalicylate, which was followed by acid cyclization to benz[b]indeno[1,2-e]pyran-11(6H)-ones 3--9 or benz[b]indeno[1,2-e]thiopyran-11(6H)-one 10, which are rare fused-ring indeno-chromones and a new indeno-thiochromone, respectively.     

Benzo[c]fused isothiazoles. I. synthesis of the angular benzo[c]bisisothiazoles and of the symmetrical benzo[c]trisisothiazole

The synthesis of all the possible angular benzo[c]bisisothiazoles ( 1, 2 and 3 ), and of the symmetrical benzo[c]trisisothiazole ( 4 ) are described. The pmr properties of these compounds are compared with analogous thiophenes and thiadiazoles     

Synthese von [1]Benzothieno[2,3—c]pyrazol-Derivaten

Derivatives of [1]benzothieno[2.3-c]pyrazole, a new heterocyclic ring system, were synthesized by 1.3-dipolar cycloadditions: benzo[b]thiophene-1.1-dioxide and derivatives thereof reacted with diazomethane and diazoethane to yield substituted [1]benzothieno[2.3-c]pyrazolines. A similar reaction with ethyl diazoacetate gave the corresponding cyclopropa[b][1]benzothiophene-2.2-dioxide derivative.