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Paper | Regular issue | Vol 32, No. 9, 1991, pp.1745-1755
Published online, 1st January, 1970
DOI: 10.3987/COM-91-5773
Pyrazoles and Isoxazoles Derived from 2-Hydroxyaryl Phenylethynyl Ketones: Synthesis and Spectrophotometric Evaluation of Their Potential Applicability as Sunscreens

Hermenegildo García, Sara Iborra, Miguel A. Miranda,* Isabel M. Morera, and Jaime Primo

*Departamento de Quimica/ Instituto de Tecnologia Quimica , UPV-CSIC, Universidad Politécnica de Valencia, Apartado 22012, E-46071-Valencia, Spain

Abstract

Reaction of the acetylenic ketones (1) with hydrazine or hydroxylamine leads to the pyrazoles (2) or the isoxazoles (3), respectively. Spectrophotometric evaluation of the UV-photoprotecting ability as compared to p-aminobenzoic acid (PABA) shows that the predicted effectiveness of 2 and the 3-phenylisoxazoles (3B) is very close to that of PABA, while that of the 5-phenylisoxazoles (3A) is clearly lower. The pyrazoles (2) are more stable than PABA upon UV-irradiation in cyclohexane solution.