18F-labelled 1,3-bis-(2-fluoroethyl) nitrosourea (18F-BFNU) (9) and 1-(2-chloroethyl)-3-(2-fluoroethyl) nitrosourea (18F-CFNU) (isomeric mixture, 11,12) were synthesized by nucleophilic attack of 18F-labelled tetra-n-butylammonium fluoride on the aziridine ring of 1,3-substituted ureas. Diethyleneurea (DEU) (5), 1-(2-fluoroethyl)-3-ethyleneurea (FEU) (7), and 1-(2-chloroethyl)-3-ethyleneurea (CEU) (14) were used as starting materials in the synthesis. Nitrosation of 18F-labelled 1,3-bis-(2-fluoroethyl) urea (18F-BFU) (6) produced 18F-BFNU with a radiochemical yield of 5–10%. Nitrosation of 18F-labelled 1-(2-chloroethyl)-3-(2-fluoroethyl) urea (18F-CFU) (15) gave 18F-CFNU as a mixture of two isomers. Geometrical isomers of CFNU were separated by hplc, and the radiochemical yield of the two isomers ranged from 8% to 15%, with a radiochemical purity exceeding 96%. Syntheses, which took about 60 min, yielded products with specific activity of 680 mCi/mmol when n-Bu4N+F− was used, or 300 mCi/mmol when HF was used to complete the opening of the aziridine ring.

ABWRACT 18Fluorine-18 labelled haloperidol ( F-HP) was synthesized by a fluorine-fluorine exchange reaction 078haloperidol, fluorinechlorine exchange on a chloro-analog of haloperidd, and from F-labelled pfluorobenzonitrile prepared by two dfferent exchange reactions. Nudeophilic fluorine was used in the form of tetra n-butyiammonium fluoride. The overall radiochemical yield, expessed at the end of syntheses UQS % for exchange in haloperidol and about 2%-3% for exchange in chloroanalog in a 40 min synthesis (from the end of the irmdiation). Specific activity up to 1 Ci/mmol for haloperidd and q to 5000 Ci/mmol for chlorwmalog as substrates were obtained. The syntheses ming psubstituted chloro-and nitro-benmnitriles as starting materials for t h e exchange reaction gave a product with an average specific activity of a tt 2000 Ci/mmol and in general an overall radiochemical yield of %-la. krification 02 F@operidoI was done by HPLC on aC-18 column. The radiochemical purity as assessed by t h n layer radiochromatography (TLRC) of t h e final ~o d u~t was at least 95%, with high chemical p i t y . Postmortem studies dare on human brain tissue have indicated a change in t h e concentration of dopaminergic receptor sites i n several diseases. (Changes i n Parkinsods disease (6) and schizophrenia (7) are of relevance to this paper.) However, s i t r e t h e tissue analyses were carried cut after the death of t h e patient, changes in the c o r r m t m t i o n of * Presentrd in part at the 187th Meeting of ACS, St. Lcuis, MO., April 8-13, 1984 (NUCL-60) and 5th Lnt. Symp. Radiopharm. Chem., Tokyo, Japan, July 9-13,1984. Towhan correspmderreshculd be addressed. KEY WORDS:

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Wistar rats implanted intracerebrally with AA ascites tumor were injected seven or eight days later with 11C-labelled BCNU. Radioactive compounds in samples of plasma, tumor, and contralateral brain were identified after injection at intervals by doing chloroform extraction and thin layer radiochromatography. At 60 min after injection radioactivity levels were 56% higher in the tumor than in contralateral brain. This increase was due mainly to 2-chlorethyl isocyanate, which binds to amino groups and/or nucleic acid. The results demonstrated both a higher concentration and a faster decomposition of BCNU in the tumor.