The important radiotracer precursor 2β-carbomethoxy-3β-(4-iodophenyl)-tropane (β-CIT, RTI-55) was made in 52% overall yield from cocaine. Key steps were improved conjugate Grignard addition to anhydroecgonine methyl ester with >3.5:1 2β: 2α-isomer selectivity, and a mild new direct aromatic iodination with I2 and silver triflate in CH2Cl2. The [11C]β-CIT was labeled at either the N or O positions with [11C]methyl triflate; and efficient reversed-phase HPLC was used to preparatively separate [N-11C]β-CIT from N-nor-β-CIT for the first time, and a fast solid-phase extraction (SPE) method was applied to preparatively separate [O-11C]β-CIT from β-CIT-acid precursor.
- monoamine transporter
ASJC Scopus subject areas
- Cancer Research
- Molecular Medicine
- Radiology Nuclear Medicine and imaging