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Two short synthetic pathways affording anti-(1,6)azulenophane (3) via fluoride-induced 1,8-eliminations from trimethylsilyl-tetraalkylammonium salts are discussed.The structural assignment of the title compound 3 is based on spectral data.Results from flash vacuum pyrolysis experiments suggest that 3 fractures at 620 deg C to generate the corresponding monomer, 1,6-azulylene (1), a highly reactive polyene.

We have developed a short, general synthetic route to 1,3,6-trisubstituted azulenes. The key intermediate, 6-methylazulene, was synthesized from readily available and inexpensive starting materials in 63% yield over two steps. The methyl group of 6-methyl

A novel catalytic method for the direct C-H alkynylation of azulenes is developed. The gold catalyzed functionalization of this special carbacycle is achieved with hypervalent iodonium reagent TIPS-EBX under mild reaction conditions. With the aid of the developed procedure, several TIPS alkynylated azulene derivatives were synthesized bearing important functional groups for further functionalization.

The reactions of halogenated propellenes with potassium t-butoxide have been investigated.Propelladiene 9,9-dichloro-1,4,5,8-tetrahydro-4a,8a-methanonaphthalene affords 1,6-methanoannulene, 4-methylazulene, and 5H-benzocycloheptene, while the related tetracyclic compound 1,1,8,8-tetrachloro-1a,2,3,6,7,7a-hexahydro-2a,6a-methano-1H-cyclopropanaphthalene reacts to give 12-chlorotricyclo3,5>dodeca-1,3(5),6,8,10-pentaene.Treatment of 8,8-dichloro-2,3,4,7-tetrahydro-3a,7a-methano-1H-indene with the same base produced a mixture of the chlorodiene 8-chloro-2,3-dihydro-3a,7a-methano-1H-indene, azulene, and 4-methylazulene.The structure of the chlorodiene was established by an X-ray crystallographic study of its Diels-Alder adduct with 4-phenyl-4H-1,2,4-triazole-3,5-dione.While reaction of tetracycle 1,1,syn-8-trichloro-1a,2,3,6,7,7a-hexahydro-2a,6a-methano-1H-cyclopropanaphthalene with base failed to produce any characterisable products, under the same conditions epimer 1,1,anti-8-trichloro-1a,2,3,6,7,7a-hexahydro-2a,6a-methano-1H-cyclopropanaphthalene was converted into the cycloproparene tricyclo3,5>dodeca-1,3(5),6,8,10-pentaene.Mechanistic proposals which account for the observed conversions have been advanced and are supported by 13C-labelling studies.The initial steps in most of the reaction pathways of the substrates are probably 1,4-elimination processes involving abstraction of an allylic hydrogen, fragmentation of the strained propellene ?-bond, and ejection of the halogen in an endo-relationship to the abstracted proton.The primary product of these processes, bridgehead dienes such as bicycloundeca-1,3,6(11),8-tetraene, 4,4,12-trichlorotricyclo3,5>dodeca-1(11), 7(12),9-triene and 10-chlorobicyclodeca-1,3,6(10)-triene, then undergo further reaction involving, amongst other things, 1,3-prototropic shifts.Attempts to probe the mode of formation of the C11-4-methylazulene from the C10-precursor 8,8-dichloro-2,3,4,7-tetrahydro-3a,7a-methano-1H-indene have uncovered a novel methylation reaction of azulene by the dimsyl anion.

The 4J coupling constants of methyl-substituted derivatives, probes of bond order, have been used to examine the ground-state ?-electron distributions in azulene (1), biphenylene (2) and 1,6-methanoannulene (3).The experimental data obtained are in good agreement with theoretical predictions for biphenylene (2) and provide some evidence for ?-electron disproportionation towards the five-membered ring in azulane (1).The bond orders in 1,6-methanoannulene (3) obtained in this work are at variance with those predicted on the grounds of bond lenghts.

A short new azulene synthesis requiring no dehydrogenation step, has been developed (Scheme 1).Intramolecular carbene addition creates the bicyclic ring system of azulene with a high degree of unsaturation and versatile functionality in a single step from a simple benzene derivative.The synthesis is particularly amenable to preparation of specific 13C- and 2H-labeled azulenes.