Oxidation-Active Flavin Mimics. Chemical and Redox Properties of 7,14- Diethyl-3,10-dimethylbenzo(1,2-g;4,5-g′)dipteridine-2,4,9,11-(3H,7H, 10H,14H)-tetraone (Benzo-dipteridine)

The chemical and redox properties of benzo-dipteridine (BDP), an oxidation-active flavin mimic, were investigated. It was found that (i) BDP undergoes 2e-redox reaction under conventionl conditions, (ii) pKa,-values of 2e-reduced BDP (BDPred), are 3.6 and 8.5, respectively, (iii) a mixture of BDPOX and BDPred forms a charge-transfer complex in aqueous solution, (iv) BDPox exhibits a remarkably high oidation activity (ca. 107-fold) toward reactions involving nucleophilic attack at the C(4a)-position compared with 3,10-dimethylisoalloxazine (DMI), and (v) the oxidation of an NADH model by BDPox is acid-catalysed. As a new model reaction, BDPox was found to oxidze sulphite ion via a BDP–SO3– adduct, which decomposes unimolecularly to give BDPH– and [SO3] in aqueous solution. This is the first example of an APS (adenosine 5′-phosphosulphate) reductase model.