Synthesis of (75)Se 5-ethoxycarbonyl-4-methyl-1,2,3-selenadiazole
Selenium-75 (t(1/2) = 120.4 d; 100% EC) was prepared in no-carrier-added form by 22 MeV proton-bombardment of natural arsenic(III) oxide powder held in a copper-aluminum drawer target (highest yield, 35muCi/muAh; maximum current, 6 muA), followed by oxidation to [(75)Se]selenium(IV) oxide. No-carrier-added [(75)Se]5-ethoxycarbonyl-4-methyl-1,2,3-selenadiazole was prepared in one step from ethyl acetoacetate semicarbazone with [75Se]selenium(IV) oxide in glacial acetic acid at 50 degreesC. Column chromatography of the final solution afforded the desired labeled compound in 30% yield and greater than 98% radiochemical purity. (C) 2004 Elsevier Ltd. All rights reserved.