Sew difluorinated derivatives of fluorene are desciibed, particularly I ,7- and 3,7-difluoro-2-acetamidofl ~orene, for cancer research. These are of interest becailse blocking metabolic hydroxylation sites mag' lead to more potent carcinogens and to mebahlic products pertinent to the origin of cancer. ... Previously3 we discussed the importance of fluo- rinated N-2-(fluorenyl)acetamides in carcinogenic- ity studies being done by Drs. J. ,4. and E. C. AIi1lerl4 and described ...