9-Phospha-bicylco [6.1.0] nona-2,4,6-triene 9-Phospha-bicylco [4.2.1.] nona-2,4,7-triene

The synthesis of the title compounds with substituents R=Alkyl, Cl, H by reaction of COT^2? with RPCl₂ at ?70°C is described.     

The dominant role of hyperconjugation in the 9-oxabicyclo[4.2.1] nona-2,4,7-triene series

The synthesis and photodimerization of 9-oxabicyclo[4.2.1]nona-2,4,7-triene are described. The electronic structure of 9-oxabicyclo[4.2.1]nona-2,4,7-triene and variously saturated derivatives thereof was examined by means of UV photoelectron spectroscopy and calculation. The combined results give no indication of specific through-space lone-pair/τ or τ/τ interaction between the various appendages but offer clear sign of hyperconjugative coupling.     

Synthesis of Si- and N-containing bicyclo[4.2.1]nona-2,4-dienes and bicyclo[4.2.1]nona-2,4,7-trienes

A [6π+2π] cycloaddition of Si- and N-containing alkynes and 1,2-dienes to cyclohepta-1,3,5-trienes in the presence of the two-component catalytic system (acac)₂TiCl₂-Et₂AlCl gives rise to the corresponding bicyclo[4.2.1]nona-2,4-diene and bicyclo[4.2.1]nona-2,4,7-triene derivatives.     

The facile isomerization of benzo[8,9]bicyclo[5.2.0]nona-2,4,8-triene to benzo[7,8]bicyclo[4.2.1]nona-2,4,7-triene promoted by L3M(CO)3 complexes (M = Cr,Mo, W). The crystal structure of the tricarbonyl complex of benzo[7,8]bicyclo[4.2.1]nona-2,4,7-triene

Benzo[8,9]bicyclo[5.2.0]nona-2,4,8-triene (I) isomerizes to benzo[7,8]bicyclo[4.2.1]nona-2,4,7-triene (II) in the presence of L₃M(CO)₃ complexes (L = CO, NH₃, CH₃CN; M = Cr, Mo, W). In THF at 40°C with (CH₃CN)₃CrCO₃ the uncomplexed II is formed together with smaller amounts of the corresponding η⁶-tricarbonylchromium complex, TCC-II. In n-butyl ether at 120°C with (NH₃)₃Cr(CO)₃ the main product is the latter complex. The structure of TCC-II has been determined by NMR and X-ray analysis.     

The equilibrium between exo- and endo-9-chloro-cis-bicyclo[4.3.0]nona-2,4,7-trienes

The title equilibrium constant has been found to be 9.0 with predominant $\text{exo}$-isomer at 25°C.     

Synthesis of anti-9-Bromo- and anti-9-Chlorobicyclo[4.2.1]nonatriene via Bicyclo[4.2.1]nonatriene→Bicyclo[4.2.1]nonatriene Rearrangement

The first syntheses of 9-bromo- and 9-chlorobicyclo[4.2.1]nona-2,4,6-trienes were each achieved in three stereoselective steps from the 9,9-bis(selenophenyl) derivative 9 in 79% overall yield for the bromide and 64% for the chloride. A deuterium-labeling experiment reveals the first rearrangement of a bicyclo[4.2.1]nonatriene which leaves the ring system intact.     

Thionin oxide as a Possible Intermediate on Periodate Oxidation of 9-Thiabicyclo[6.1.0]nona-2,4,6-triene

9-Thiabicyclo[6.1.0]nona-2,4,6-triene was oxidized at ?15 to ?20°C with sodium periodate in a methanol-water medium. The major isolated product was established as $\text{cis}$3a,7a-dihydrobenzo[b]thiophene-$\text{cis}$-1-oxide, which is best explained as arising from intramolecular cycloaddition of a thionin oxide intermediate.