Synthesis of 2‐[ 11 C]methoxy‐3,17β‐estradiol to measure the pharmacokinetics of an antitumor drug candidate, 2‐methoxy‐3,17β‐estradiol

2‐Methoxy‐3,17β‐estradiol, an endogenous estrogen metabolite, showed cytotoxicity in various cancer cell lines and also has antiangiogenic and proapoptotic activities. Clinical I and II trials of 2‐methoxy‐3,17β‐estradiol for multiple myeloma, advanced solid tumors, metastatic breast and prostate cancer are underway. We prepared 2‐[ 11 C]methoxy‐3,17β‐estradiol to measure the pharmacokinetics and organ distribution of 2‐methoxy‐3,17β‐estradiol in clinical trials. 2‐[ 11 C]Methoxy‐3,17β‐estradiol was synthesized from a precursor, 2‐hydroxy‐3,17β‐ O ‐bis(methoxymethyl)estradiol, in two steps with over 99% radiochemical purity. The overall reaction time was 45 min and the decay‐corrected radiochemical yield was 32.9%. The distribution coefficient (logP 7.4 ) of 2‐[ 11 C]methoxy‐3,17β‐estradiol at pH 7.4 was measured as 2.95. Copyright © 2006 John Wiley & Sons, Ltd.