PHOTOCHEMICAL ADDITION OF L‐LYSINE TO 1,3‐DIMETHYL‐4‐THIOURACIL*

Abstract
—: Irradiation of an aqueous solution of 1,3‐dimethyl‐4‐thiouracil (1) in the presence of l‐lysine (2) with a high‐presure mercury lamp through a Pyrex filter gave a 1:1 mixture of two photoproducts. One of the products was isolated in a pure form, which on treatment with acetic anhydride‐pyridine yielded the starting material 1. Based on the spectral data (1H and 13C NMR) and the chemical reaction, the structure of the photoproduct was assigned to 3. The photochemical reaction is considered as a nucleophilic addition of l‐lysine to photoexcited 1.