HETEROCYCLIC METHYL FREE RADICALS AS IMAGE ENHANCING AGENTS

摘要

The invention provides novel persistent free radicals useful in Overhauser MRI being triarylmethyl radicals having as at least one aryl group a group of formula (1) or (2), wherein each X which may be the same or different is an oxygen or sulphur atom or a group CO or S(O)n (where n is 1 to 3) with the proviso that at least one group X is a sulphur atom or an S(O)n group; R<1> is a hydrogen atom or group of formula -M, -XM, -X-Ar<2> where M is a water solubilising group, and Ar<2> represents a 5-10 membered aromatic ring optionally substituted by a water solubilising group M; and each of the groups R<7>, which may be the same or different, is a hydrogen atom, or a hydrocarbon group or a water solubilising group M, or two groups R<7> together with the atom to which they are bound represent a carbonyl group or a 5 to 8 membered cycloalkylidene, mono- or di-oxacycloalkylidene, mono or di-azacycloalkylidene or mono- or di-thiacycloalkylidene group optionally wit the ring attachment carbon replaced by a silicon atom, and R<7> where it is other than hydrogen, is optionally substituted by a hydroxyl group, an optionally alkoxylated, optionally hydroxylated acyloxy or alkyl group or a water solubilising group M. The novel radicals have good stability, long relaxation times and good relaxivity.