The synthesis of novel fluorinated bisphosphonates with two, three, four, and six difluoromethylene groups (la, lb, 8, 12, and 15)(44-78%) by different approaches is described. The bisphosphonates were converted to the corresponding trimethylsilyl esters which on treatment with deionized water afforded the respective bisphosphonic acids (6, 10, and 14) in good yields.
[Hu, Chang-Ming; Chen, Jian Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1993 , # 3 p. 327 - 330]