A tetrafluoro-substituted aryl azide 1 and its protio analogue 2, both photoaffinity labeling reagents for the estrogen receptor, have been prepared by direct coupling of the appropriately substituted Cazidobenzoyl chloride with the electron rich C-3 of 6-methoxy-2- (4methoxyphenyl) benzo [blthiophene 3. This represents a rare example of aryl azide stability under Friedel-Crafts acylation conditions. Alternatively, the protio analogue 2 can ...
