N.C.A. 11C-labelling of benzenoid compounds in ring positions: Synthesis of nitro-[1-11C]benzene and [1-11C]aniline
作者:J. Steinbach、P. Mäding、F. Füchtner、B. Johannsen
DOI:10.1002/jlcr.2580360104
日期:1995.1
The paper describes the first method for n.c.a 11C-ring labelling of benzenioid compounds having a reactive group for further derivatization by use of the known principle of synchronous six-electron cyclization of hexatriene systems into aromatics. Nitro-[11C]methane (1) prepared from cyclotron-produced [11C]carbon dioxide reacts in the presence of t-BuOK with 5-dimethylaminopenta-2,4-dienylidene-dimethylammonium perchlorate (2) to form 6-nitro-1-dimethylamino-[6-11C]hexatriene (3) follow by cyclization/ aromatization into nitro-[1-11C]-benzene (4) at increased temperatures. Starting from 1, nitro-[1-11C]benzene of a radiochemical purity of about 92 % and a mean specific radioactivity of 1 Ci/μmol was obtained within 7 min. Related to [11C]CO2, the reproducible radiochemical yield of 4 (decay-corrected) was 80±5 %. Reduction of 4 by heating the above reaction mixture with aqueous Na2S gave [1-11C]aniline (5) of aradiochemical purity of about 81 %. The reproducible radiochemical yield of 5 (decay-corrected) in relation to [11C]CO2 was 65±5 %, the synthesis time from 1 was 18 min.
该论文描述了首个用于对具备进一步衍生化活性基团的苯环类化合物进行n.c.a 11C-环标记的方法,该方法利用已知的六电子环化将己三烯系统同步转化为芳香族化合物的原理。由回旋加速器产生的[11C]二氧化碳制备的硝基[11C]甲烷(1),在叔丁基钾的存在下与5-二甲氨基戊-2,4-二烯基二甲基铵高氯酸盐(2)反应,形成6-硝基-1-二甲氨基[6-11C]己三烯(3),随后在升温条件下环化/芳香化成硝基[1-11C]苯(4)。从1开始,在7分钟内获得了放射化学纯度约为92%、平均比放射性为1 Ci/μmol的硝基[1-11C]苯。相对于[11C]CO2,4的可重复放射化学产率(衰变校正)为80±5%。通过在上述反应混合物中加热与水溶液Na2S反应,将4还原,得到放射化学纯度约为81%的[1-11C]苯胺(5)。相对于[11C]CO2,5的可重复放射化学产率(衰变校正)为65±5%,从1开始的合成时间为18分钟。