jo981920r_si_001.pdf (1.13 MB)
Synthesis of Lipophilic Paramagnetic Contrast Agents
journal contribution
posted on 1999-03-31, 00:00 authored by William C. Baker, Michael J. Choi, Daniel C. Hill, Julie L. Thompson, Peter A. PetilloThe 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.