Abstract By oxidative cyclization of 5, 5′-arylmethylenebis (6-methylaminouracil) derivatives with diethyl azodicarb-oxylate a number of 5-deazaisoalloxazines were synthesized having at the C (8) position a substituent that causes a bathochromic shift varying between 20 and 130 nm, depending on the substituent. To increase the solubility in aqueous media 8-substituted 5-deazaflavins were prepared having a carboxymethyl ...