Dibenzo dioxocins

Karhunen, P Rummakko, P. Sipila, J. Brunow, G. Kilpelainen, I. Dibenzo- dioxocins a novel type of linkage in softwood lignins. Tetrahedron Lett. 1995, 36, 169-170. 

Diode array-UVD (DA-UVD) 953 1,3,2-Dioxaborins, formation of 683 Dioxanes—see 1,3-Benzodioxanes Dioxepens—see Dibenzodioxepens Dioxins—see Dibenzo-p-dioxins Dioxiranes, as oxidants 1255, 1257, 1258 Dioxocines—see Dibenzodioxocines Dioxygen-copper complexes, as oxidants 1194, 1198... 

The 1,2-dioxocin ring system has received a rather surprising amount of attention, at least in relation to the other compounds discussed in this chapter (with the exception of the 1,2-diazocines). The vast majority of these reports deal with essentially two compounds, namely the 5,8-dialkoxy-5,8-dihydro-dibenzo[fi /][l,2]dioxocins (50) obtained from the ozonolysis of phenanthrene, and the corresponding 5,8-dione (51) ( diphenoyl peroxide ), but a substantial number of other derivatives have also appeared since the publication of CHEC-I in which only a single derivative was reported. 

Molecular mechanics have been used to address the favored conformations for [3,3]-sigmatropic rearrangement of (E)- and (Z)-2-thione derivatives <90TL5471, 91TLI203> and to explore the conformational preferences of dibenzo[d, ]dioxocins <89Z0R657,9UST165,91Z0BI73), as discussed further below. 

Single crystal x-ray diffraction analysis of 12/f-dibenzo[rf, ][l,3]dioxocin-12-one (56) has been carried out <91JST165>. This apparently represents the only detailed structural study of any 1,3-diheterocin reported. Unfortunately, only partial data was presented. Reported bond angles appear... 

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