Synthesis and preliminary biological evaluation of MMP inhibitor radiotracers [¹¹C]methyl-halo-CGS 27023A analogs, new potential PET breast cancer imaging agents

A series of [¹¹C]methyl-halo-CGS 27023A analogs (2-F, 1a; 4-F, 1b; 2-Cl, 1c; 3-Cl, 1d; 4-Cl, 1e; 2-Br, 1f; 3-Br, 1g; 4-Br, 1h; 4-I, 1i), novel radiolabeled matrix metalloproteinase (MMP) inhibitors, have been synthesized for evaluation as new potential positron emission tomography (PET) breast cancer imaging agents. The precursors halo-CGS 27023A analogs (2-F, 6a; 4-F, 6b; 2-Cl, 6c; 3-Cl, 6d; 4-Cl, 6e; 2-Br, 6f; 3-Br, 6g; 4-Br, 6h; 4-I, 6i) for radiolabeling were obtained in four steps from starting material amino acid D-valine with moderate to excellent chemical yields. Precursors were labeled by [¹¹C]methyl triflate through ¹¹C-O-methylation method at the aminohydroxyl position under basic conditions and isolated by solid-phase extraction (SPE) purification to produce pure target compounds in 40-60% radiochemical yields (decay corrected to end of bombardment), in 20-25 min synthesis time.