Dihydroflavins derivatives

The 1,10-benzo-bridged dihydroflavin derivative of Knappe (97) yields a 420-nm-intermediate upon autoxidation, and even a relatively stable one, though addition at lOa must clearly be disfavoured in this... 

Dihydroflavin exhibits rather diffuse visible absorption characteristics (cf. Table 4). In contrast, the derivatives (20), (21), (23) and (24) show well-defined spectra. The absorption maxima occur at 430 nm ((20)), 360 nm ((21)), 400 nm... 

Flavine derivatives oxidize thiols to disulphides in the absence of oxygen with formation of dihydroflavines (equation 92). 

Derivatives of other l,n-dihydroflavins will be discussed in the chapter on flavin oxygen adducts (see below), where position n means a carbon atom substituted by a strongly electronegative group such as OH, OR, OOH, etc. The dilemma encountered in the determination of the redox state (chromophore = dihydroflavin, redox balance = flavoquinone) of such compounds, e.g. hydroxydihydrofiavins , has been discussed in the Nomenclature chapter (cf. above). 

Photodehydrogenation (or, entirely equivalent to it, photodecarboxylation) follows equation (19), the most common course of flavin photochemistry. It involves a net reduction, yielding free dihydroflavins or alkyl derivatives thereof... 

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