A high-yield route to synthesize the P-glycoprotein radioligand [ C]N-desmethyl-loperamide and its parent radioligand [ C]loperamide
作者:Min Wang、Mingzhang Gao、Qi-Huang Zheng
DOI:10.1016/j.bmcl.2013.08.024
日期:2013.10
N-Desmethyl-loperamide and loperamide were synthesized from a, a-diphenyl-c-butyrolactone and 4-(4-chlorophenyl)-4-hydroxypiperidine in five and four steps with 8% and 16% overall yield, respectively. The amide precursor was synthesized from 4-bromo-2,2-diphenylbutyronitrile and 4-(4-chlorophenyl)-4-hydroxypiperidine in 2 steps with 21-57% overall yield. [C-11] N-Desmethyl-loperamide and [C-11] loperamide were prepared from their corresponding amide precursor and N-desmethyl-loperamide with [C-11] CH3OTf through N-[C-11] methylation and isolated by HPLC combined with solid-phase extraction (SPE) in 20-30% and 10-15% radiochemical yields, respectively, based on [C-11] CO2 and decay corrected to end of bombardment (EOB), with 370-740 GBq/lmol specific activity at EOB. (C) 2013 Elsevier Ltd. All rights reserved.