Coumarins constitute an important class of naturally occurring compounds with useful phar-macological activity.~1,2 Numerous coumarins were used as steroid receptor modulators~3 and photopolymerization initiators~4. Some attention has been paid to trifluoromethyl substituted coumarins as fluorescent markers for synthetic proteinases~5,6 and also as laser dyes.~7 Recently, a number of coumarins, inclusive of fluorine containing ones, were patented as optical molecular sensors.~8 In all these applications only 4-trifluoromethyl substituted coumarins were used; they were synthesised by the zinc chloride catalysed condensatio of phenols with 4,4,4-trifluoroacetoacetate (Pechmann reaction).~5,6 Enantioselective cathodic reduction of 4-(trifluoromethyl)coumarin with alkaloids as chiral catalysts was investigated; this resulted in 4-(trifluoromethyl)coumarin with alkaloids as chiral catalysts was investigated; this resulted in 4-(trifluuoromethyl)-3,4-dihydroxoumarin as the amin product (28 yield and 8.4 ee).~9 A number of 3-perfluoroalkyl substituted coumarins were prepared by a sodium hydroxymethanesulfinate (Rongalite) initiated reactions of perfluoroalkyl iodides with coumarins~10 or by reactions of coumarins with perfluoroalkanesulphinates~11 in the presence of oxidants but no 3-(trifluoromethyl)coumarins were obtained by those methods. The only successful preparation of 3-trifluoromethyl substituted coumrins reported so far involves reactions of coumarins with bis(trifluoroacetyl) peroxide.~12
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