title: A robust and convergent synthesis of dipeptide-DOTAM conjugates as chelators for lanthanide ions: new PARACEST MRI agents.
abstract: A generally applicable synthetic approach to dipeptide-DOTAM conjugates has been developed which is based on the peralkylation of 1,4,7,10-tetraazacyclododecane (cyclen) with protected N-iodoacetyl dipeptides. Standardized procedures were used for the alkylation, metalation, and purification of the resultant lanthanide complexes. Using this approach, we have been able to rapidly and reliably prepare and screen five different ligands each with up to six lanthanide ions. This preliminary investigation has identified several paramagnetic compounds with strong chemical exchange saturation transfer (PARACEST) properties in water at physiological temperature and pH. Extension of the synthetic approach to a wide variety of amino acids is possible.
authors: Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7.
authors: Filip
authors: F
authors: Wojciechowski
authors: Mojmir
authors: M
authors: Suchy
authors: Alex X
authors: AX
authors: Li
authors: Hassan A
authors: HA
authors: Azab
authors: Robert
authors: R
authors: Bartha
authors: Robert H E
authors: RH
authors: Hudson
mesh_terms: D000081:Acetamides / Q000138:chemical synthesis*; D000478:Alkylation; D002614:Chelating Agents / Q000138:chemical synthesis*; D003287:Contrast Media / Q000737:chemistry*; D000080027:Cyclams; D004151:Dipeptides / Q000138:chemical synthesis*; D006571:Heterocyclic Compounds / Q000737:chemistry; D006573:Heterocyclic Compounds, 1-Ring / Q000138:chemical synthesis*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D008279:Magnetic Resonance Imaging; D008956:Models, Chemical; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D013696:Temperature
chemical_list: C522450:1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane; D000081:Acetamides; D002614:Chelating Agents; D003287:Contrast Media; D000080027:Cyclams; D004151:Dipeptides; D006571:Heterocyclic Compounds; D006573:Heterocyclic Compounds, 1-Ring; D007477:Ions; D028581:Lanthanoid Series Elements; D008024:Ligands; D009942:Organometallic Compounds; C038072:cyclen