Synthesis of 18F-labeled phenolphthalein and naphtholphthalein.
The fluorination of phenolphthalein and naphtholphthalein was performed with diluted fluorine gas under acidic conditions. For both compounds we observed an electrophilic fluorination into ortho position to the hydroxyl group. Through the use of this reaction we synthesized and characterized mono-and difluorinated derivatives of phenolphthalein and naphtholphthalein. The compounds were also prepared in the 18F labeled form, which are usable as a new type of probe for in vivo pH measurement in biological objects using Cerenkov imaging or combination of light absorption and PET.
Synthesis and characterization of fluorinated derivatives of cresolsulfonphthalein.
The reaction between dilute fluorine gas and cresolsufonphthalein in acetic acid was investigated. The mono-, di-, and trifluorinated cresolsufonphthalein derivatives were isolated and characterized. These compounds possessed the properties of pH indicators with biologically relevant pKa values (6.4-7.5) and the absorption maxima of the basic forms at 582-592 nm. This method can be used for synthesis of positron-emitting 18F-labeled pH indicators with potential application for non-invasive in vivo pH measurement in biological objects.
Elemental fluorine in organic chemistry (1997–2006)
Abstract The use of elemental fluorine as a reagent over the period 1997–2006 for carbon–fluorine bond formation in organic synthesis is reviewed. Recent advances in the exhaustive fluorination of ethers and esters to give perfluorinated systems, selective direct fluorination of aliphatic, aromatic, heterocyclic and carbonyl systems and the application of microreactor techniques to direct fluorination are discussed.