Synthesis and in vivo evaluation of [11C]MPTQ: A potential PET tracer for alpha2A-adrenergic receptors

Radiosynthesis and in vivo evaluation of [N-methyl-11C] 5-methyl-3-[4-(3-phenylallyl)-piperazin-1-ylmethyl]-3,3a,4,5-tetrahydroisoxazolo[4,3-c]quinoline (1), a potential PET tracer for alpha2-adrenergic receptors is described. Syntheses of nonradioactive standard 1 and corresponding desmethyl precursor 2 were achieved from 2-aminobenzaldehyde in 40% and 65% yields, respectively. Methylation using [11C]CH3I in presence of aqueous potassium hydroxide in DMSO afforded [11C]1 in 25% yield (EOS) with >99% chemical and radiochemical purities with a specific activity ranged from 3-4 Ci/μmol (n = 6). The total synthesis time was 30 min from EOB. PET studies in anesthetized baboon show that [11C]1 penetrates BBB and accumulates in alpha2A-AR enriched brain areas.