%0 Journal Article %A Baker, William C. %A Choi, Michael J. %A Hill, Daniel C. %A Thompson, Julie L. %A Petillo, Peter A. %D 1999 %T Synthesis of Lipophilic Paramagnetic Contrast Agents %U https://acs.figshare.com/articles/journal_contribution/Synthesis_of_Lipophilic_Paramagnetic_Contrast_Agents/3716325 %R 10.1021/jo981920r.s001 %2 https://acs.figshare.com/ndownloader/files/5807889 %K series %K monoalkylation %K excess %K gadolinium complexes 9 %K contrast agents %K PCA %K methodology %K macrocycles 7 %K transformation %K synthesis %K carboxymethylated analogues 8 %K Alkylated cationic intermediates 6 %K yield %K compound %K alkyl iodides %K cyclen %K tunable lipophilicity %K glyoxal adduct %K Lipophilic Paramagnetic Contrast Agents %K Synthesi %X The facile, high-yielding synthesis of a series of macrocycles 7ak in 75−100% yield is reported. The transformation of these compounds to their carboxymethylated analogues 8ak in 75−90% yield and subsequent gadolinium complexes 9ak provides a series of homologous neutral paramagnetic contrast agents (PCAs) with tunable lipophilicity. Alkylated cationic intermediates 6ak 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. %I ACS Publications