Novel prodrugs of estradiol

1 . A prodrug derivative of estradiol having the following formula:

and enantiomers and pharmaceutically acceptable salts thereof, wherein X is selected from the group consisting of

2 . The prodrug of claim 1 , wherein X is

3 . A pharmaceutical dosage unit comprising:

(a) a prodrug derivative of estradiol having the following formula:

and enantiomers and pharmaceutically acceptable salts thereof, wherein X is selected from the group consisting of

and

(b) one or more pharmaceutically acceptable excipients.

4 . A method of providing contraception comprising the step of:

administering to a patient in need thereof, an effective amount of said prodrug derivative of estradiol of claim 1 , for an effective period of time.

5 . A method of providing hormone treatment therapy to a patient in need thereof, comprising the step of:

administering to said patient in need thereof, an effective amount of said prodrug derivative of estradiol of claim 1 , for an effective period of time.