title: Synthesis of Lipophilic Paramagnetic Contrast Agents.
abstract: The facile, high-yielding synthesis of a series of macrocycles 7a-k in 75-100% yield is reported. The transformation of these compounds to their carboxymethylated analogues 8a-k in 75-90% yield and subsequent gadolinium complexes 9a-k provides a series of homologous neutral paramagnetic contrast agents (PCAs) with tunable lipophilicity. Alkylated cationic intermediates 6a-k are prepared in yields of 72-94% from glyoxal adduct of cyclen (5) and slight excesses of alkyl iodides. The methodology is selective for monoalkylation and amenable to large-scale synthesis.
authors.affiliation: Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801.
authors.forename: William C.
authors.initials: WC
authors.lastname: Baker
authors.forename: Michael J.
authors.initials: MJ
authors.lastname: Choi
authors.forename: Daniel C.
authors.initials: DC
authors.lastname: Hill
authors.forename: Julie L.
authors.initials: JL
authors.lastname: Thompson
authors.forename: Peter A.
authors.initials: PA
authors.lastname: Petillo