O2

ArCHROO'-ArCOR, etc.

Scheme 2

Scheme 3

The results from the irradiation of naproxen (1) in water are shown in Scheme 3,111,83 and a related chemical course is followed with several drugs pertaining to this group, such as ibuprofen (5),24 butibufen (6),25 flurbiprofen (7),24 ketoprofen (8),20> 26> 27 suprofen (9),28 benoxaprofen (10),19> 22> 25> 29 tiaprofenic acid (ll)30 (Scheme 4) and ketorolac tromethamine (12) (Scheme 5).31 The triplet state is responsible for initial decarboxylation. Some detailed mechanistic studies have been carried out;26'29 in the case of ketoprofen, as an example, it has been shown that the fast decarboxylation of the triplet in water (xT 250 ps, quantum yield 0.75) may involve an adiabatic mechanism via internal charge transfer and, in part, ionisation.26

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