Photoreaction of 3,4-dimethoxy-1-nitrobenzene with butylamine. A pH dependence of regioselectivity

Abstract

Irradiation of 3,4-dimethoxy-1-nitrobenzene in the presence of butylamine leads to the formation of both possible photosubstitution products, i.e., 2-methoxy-4-nitro-N-butylaniline and 2-methoxy-5-nitro-N-butylaniline with the predominance of the latter. Regioselectivity of the reaction as measured by molar ratio of the two isomeric products varies with pH of the solution, ranging from 3 : 1 at pH 10 to 12. The results are discussed in view of possible use of 3,4-dimethoxy-1-nitrobenzene moiety as a lysine-directed photoaffinity probe.