Addition of 9-Diazofluorene to Unsubstituted and Chloro-Substituted 1,4-Benzoquinones. A Comparison with the Addition of Diphenyldiazomethane

Article abstract of DOI:10.1246/bcsj.62.2580

Unsubstituted 1,4-benzoquinine (1a) reacted at the C=C double bond with 9-diazofluorene (9-DF) to give norcarene dione 2a and 4,7-dihydroxy-3H-indazole 4a.Similarly, the reaction of 2-chloro-1,4-benzoquinone (1b) with 9-DF yielded norcarene dione 2b and 4,7-dihydroxy-3H-indazole 4b, together with tricyclic dione 3b. 2,3-dichloro-1,4-benzoquinone (1c) and 9-DF produced norcarene dione 2c, 4,7-dihydroxy-3H-indazole 4c, and its fluorenyl ether 5c.Reactions of 2,5- and 2,6-dichloro- and trichloro-1,4-benzoquinones (1d, 1e, and 1f) with 9-DF provided norcarene diones 2d, 2e, and 2f and tricyclic diones 3d and 3e, respectively.On the other hand, tetrachloro-1,4-benzoquinone (1g) converted 9-DF into 9,9'-bifluorenylidene possibly via a 1 : 1 betaine intermediate arising from the C=O double bond addition.These results were markedly different from those of the previous diphenyldiazomethane reactions and are discussed in terms of structural changes of these diazoalkanes.