Bimanes. 6. Reactive halogen derivatives of syn- and anti-1,5-diazabicyclo[3.3.0]octadienediones (9,10-dioxabimanes)

Article abstract of DOI:10.1021/jo00321a029

The preparation of reactive halogen derivatives of syn- and anti-1,5-diazabicyclo[3.3.0]octadienediones (9,10-dioxabimanes) is accomplished through the intermediate monobromo- and dibromobimanes previously described. Mono- and dihydroxy compounds are produced from the bromides by reaction with wet sodium trifluoroacetate in CH₃CN and are used to prepare the (a) monochlorides and dichlorides (SOCl₂) and (b) the monofluorides and difluorides (Et₂NSF₃). Monofunctional halides react with nucleophiles (amines, thiols, carboxylates) to yield direct substitution products, with some reduction accompanying the thiol reaction. Difunctional halides react with excess nucleophile to give direct disubstitution products. syn-Dihalides react with difunctional nucleophiles (actual or potential, e.g., RNH₂, S^2-, (CN)₂C<) to yield a new series of heterocyclic compounds, the "bridged" 9,10-dioxabimanes. The absorption spectra of both syn- and anti-(XCH₂,CH₃)B are markedly affected by the nature of X. Most syn-bromobimanes are nonfluorescent and are moderately photosensitive, due to thermally reversible isomerizations and additional irreversible reactions. syra-Chlorobimanes are nonfluorescent to weakly fluorescent. syn-Monofluoro- and difluorobimanes are strongly fluorescent. At 77 K, the halogenated compounds are all phosphorescent to some extent and many of the syn derivatives are strongly fluorescent.