Methods for the large-scale synthesis of psoralen furan-side monoadducts and diadducts

We report methods for the preparation of multimicromole quantities of extremely pure uniquely photo-adducted psoralen-DNA furan-side monoadducts and diadducts (cross-links). The methods use high-intensity krypton and argon ion lasers in the photoreactions and HPLC methods to purify the required oligonucleotides containing the photoadducts. With these methods we have synthesized 2-3 mumol of 8-mer psoralen furan-side monoadduct and diadduct. These methods allow one to generate large amounts of psoralenated DNA oligonucleotides and facilitate their study by NMR and x-ray crystallography.