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IN SITU GENERATION OF PSORALENS BY PHOTOLYSIS OF WATER‐SOLDBLE PRECURSORS
Author(s) -
Mohammad Taj,
Morrison Harry
Publication year - 1992
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1992.tb08504.x
Subject(s) - photodissociation , chemistry , aqueous solution , in situ , photochemistry , solubility , aqueous medium , quantum yield , organic chemistry , fluorescence , optics , physics
— The poor water solubility of typical photochemotherapeutic psoralens restricts their utility in aqueous solutions and commonly requires the use of organic co‐solvents in photobiological studies. This paper describes the preparation of readily water‐soluble “pre‐psoralens”, (Z)‐3‐[5‐(4,6‐dimethoxy)benzofuranyl]propenoic acid (3) and (Z)‐3‐[5‐(6,7‐dimethoxy)benzofuranyl]propenoic acid (4), and their novel photocyclization in aqueous media to give 5‐methoxypsoralen (5‐MOP) and 8‐methoxypsoralen (8‐MOP), respectively. Quantum efficiencies, measured at 308 nm for the cyclization, are 12. 1 × 10 ‐3 for 3 → 5‐MOP and 2.7 × 10 ‐3 for 4 → 8‐MOP. 5‐Methoxyisopsoralen (5‐MOiP, 5) is a side product from the photolysis of 3. Photocross‐linking of calf thymus DNA is effected when the “pre‐psoralens” are irradiated with 308 or 355 nm (3 only) light.