Deca-2,4,6,8-tetraene

Dehydrofluorination of 9-chloro-9,10,10-trifluorobicyclo[6.2.0]deca-2,4,6-triene (24) with methyllithium affords a mixture of 10-chloro-9,10-difluorobicyclo[6.2.0]deca-2,4,6,8-tetraene (25) and 9-chloro-10-methylbicyclo[6.2.0]deca-l,3,5,7,9-pentaene (26) in 18 and 6% yield, respectively.8 The former compound has been established as the intermediate for the generation of the latter one. Indeed, treatment of the fluoride 25 with methyllithium also gives the monochloride.8... 

The conrotatory cyclization of fl//-cw-deca-2,4,6,8-tetraene to traw-7,8-dimethyl-cycloocta-l,3,5-triene has been studied in solvents of different polarity [157]. In agreement with a synchronous eonrotatory ring closure via an isopolar activated complex, the solvent effect is negligible as shown by the relative first-order rate constants in Eq. (5-52). 

The skeletal rearrangement of various strained cyclic compounds is carried out with a catalytic amount of soluble complexes of PdCl2. Namely, the rearrangements of bulvalene (67) to bicyclo[4.2.2]deca-2,4,7,9-tetraene (68)[54], cubane (69) to cuneane (70)[55], hexamethyl Dewar benzene (71) to hexa-methylbenzene (72)[56], and 3-oxaquadricyclanes[57] and quadricyclane (73) to norbornadiene[58-60] take place mostly at room temperature. Reaction of iodocubane (74) with a terminal alkyne catalyzed by Pd(0) and CuBr unexpectedly affords an alkynylcyclooctatetraene 75, without giving the desired cubylalkyne 76. Probably the rearrangement is a Pd-catalyzed reaction[61]. 

When colorless crystals of rac-s-trans-3,8-di-tert-butyl-l,5,6,10-tetraphenyl-deca-3,4,6,7-tetraene-l,9-diyne (123) were heated at 140 °C for 2 h, the ben-zodicylobutadiene derivative (126) was produced as green crystals. As shown in the sequence (Scheme 20), 123 is first isomerized to its s-ds-isomer (124), and intramolecular thermal reaction of the two allene moieties through a [2+2] conrotatory cyclization gives the intermediate 125, which upon further thermal reaction between acetylene moieties gives the final product 126 [19,22].This is another example of the crystal-to-crystal reaction. 

Oxa-2,7-methanoindene or 2,7-methanobenzofuran rather than 10-oxatricyclo[3.3. l.l3,9 ]deca-l(9),3,5,7-tetraene... 

The cobalt(I)-catalysed 6 + 2-cycloadditions of cyclooctatetraene with monosubsti-tuted alkynes produced monosubstituted bicyclo[4.2.2]deca-2,4,7,8-tetraenes in good yields.185 The 6 + 3-cycloaddition of fulvenes (145) with 3-oxidopyrylium betaines (144) formed 5-8 fused oxa-bridged cyclooctanoids (146,147), which can be manipulated by cycloaddition reactions to produce key intermediates (148,149) for the synthesis of fused cyclooctanoid natural products e.g. lancifodilactones (Scheme 38).186,187... 

Diaza-anti-tricyclo(4.2.2.22 5ldo-deca-3,7,9,ll-tetraen 4,8-Diamino- (Bis-hydrochlorid) IV/5a. 587... 

Dithia, 12,14.15-triaza-penta-cyclo[9.3.1.13-9.02 °.04, ]hexa-deca-llS,5,11,13-tetraen ... 

Alkylation. The ketone (I) undergoes base-catalyzed O-alkylaiion by the reagent to give (2 7-mcthoxybicyclo[4.2.2]deca-2.4,7,9-tetraene) in 93-95% yield. Thus treatment of (1) with potassium t-butoxide (3 eq., 4 min.) and then with methyl fluoro-sulfonate (3 eq., 3 min.) in HMPT at 5° gives (2) in high yield. Significant C-alkylation is observed in less polar environments. 

C2iiH32NjOj, 1,5,9,13-Tetraazacyclohexa-deca-l,4,9,12-tetraene, 2,12-dimethyl-3,ll-bis(l-methoxyethylidene)-, nickel complex, 27 264... 

Skeletal rearrangements are rare, but are found for strained bi- and polycyclic alkenes, e.g., bullvalene , bicyclo[4.2.2]deca-2,4,7,9-tetraene , 4,5-exo-trimethylene-2-norbornene , 6-methylenebicyclo[3.1.1]heptane ", 5-methylbicyclo[2.1.1] hexene N-benzyl-9-aza-bicyclo[4.2.2]deca-2,4,7-triene , dibenzobicyclo[2.2.2]-octatriene derivatives and bornylene ... 

By Photorearrangement of Iminoether 13 8-Methoxy-7-azabicyclo[4.2.2]deca-2,4,7,9-tetraene (13,2.4 g, 0.015 mol) was dissolved in reagent grade acetone (500 mL) and this solution was irradiated through a Pyrex filter sleeve as above. After 8 h, the solvent was evaporated in vacuo, and the resulting yellowish oil was dissolved in hexane (50-75 mL) and clarified by filtration through neutral alumina. Concentration afforded a colorless oil which was crystallized from pentane to give the product yield 2.1 g (88%) as white crystals, mp 49.5-50.5 C, identical in all respects with the sample from lactam 12. 

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