8-Methoxypsoralen-Nucleic Acid Photoreaction. Effect of Methyl Substitution on Pyrone vs. Furan Photoaddition

Article abstract of DOI:10.1021/jm00370a017

We have synthesized a series of 8-<3H>methoxypsoralens in which methyl and hydrogen are systematically varied at the 4- and 5'-positions.Analysis of the products resulting from the photoaddition of these four psoralens with the nucleic acid poly(dA-dT) reveals that the product distribution depends on the presence or absence of a 4-methyl substituent.Compounds with the 4-methyl group show an overwhelming preference (ca.98percent) for addition to the furan double bond, while compounds without the 4-methyl show a substantial amount (ca.18percent) of addition to the pyrone double bond.