Popis: |
The preparation of the title compound, a selective 5-HT 3 antagonist with anti-emetic properties, is described. The key intermediate involved is 6-bromo-1,2-dihydronaphthoic acid (5), which was synthesized from 4-bromophenylacetic acid by Micheal addition, acid-induced ring cyclization, reduction and dehydration. Compound (5) was selected because it has two labelling sites to ensure high specific activity of the final product. Reduction of amide 6 with carrier-free tritium gas, followed by reduction of the amide functional group with BF 3 -OEt 2 and intramolecular cyclization furnished the title compound having a specific activity of 70.4 Ci/mmol and >99% purity. |