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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1992-7-27
pubmed:abstractText
Unlabeled fluoro- and iodo-substituted ligands exhibiting very high affinity and selectivity for sigma receptors were synthesized based on three different structural classes of sigma receptor ligands. These compounds were evaluated for sigma receptor affinity and specificity in order to assess their potential as PET/SPECT imaging agents. Thus, (+)- and (-)-N-(5-fluoro-1-pentyl)normetazocines [(+)- and (-)-4] based on the (+)-benzomorphan class of sigma ligands were synthesized via N-alkylation of optically pure (+)- and (-)-normetazocine with 5-[(methylsulfonyl)oxy]-1-pentyl fluoride (11). (+)- and (-)-4 displaced [3H](+)-3-PPP with Ki values of 0.29 and 73.6 nM and [3H](+)-pentazocine with Ki values of 10.5 and 38.9 nM, respectively. The second class of PET/SPECT ligands was based upon the N-(arylethyl)-N-alkyl-2-(1-pyrrolidinyl)ethylamine class of sigma ligands; N-[2-(3,4-dichlorophenyl)-1-ethyl]-N-(3-fluoro-1-propyl)-2-(1- pyrrolidinyl)ethylamine (5) was obtained via N-alkylation of N-[2-(3,4-dichlorophenyl)-1-ethyl]-2-(1-pyrrolidinyl)ethylamine (14) with 3-fluoropropyl p-toluenesulfonate. 5 exhibited Ki values of 4.22 and 5.07 nM for displacement of [3H](+)-3-PPP and [3H](+)-pentazocine, respectively, comparable with the parent N-propyl compound. Attempts to synthesize N-[2-(3,4-dichlorophenyl)-1-ethyl]-N-[3- [(methylsulfonyl)oxy]-1-propyl]-2-(1-pyrrolidinyl)ethylamine (26), a precursor to 5 that could conceivably be converted to [18F]-5 by treatment with 18F-, proved unsuccessful. The sequence of regioselective nitration, catalytic hydrogenation, and diazotization followed by NaI quench of N-[2-(3,4-dichlorophenyl)-1-ethyl]-N-methyl-2-(1- pyrrolidinyl)ethylamine (2) afforded the iodinated ethylenediamine N-[2-(2-iodo-4,5-dichlorophenyl)-1-ethyl]-N-methyl-2-(1- pyrrolidinyl)ethylamine (8), a potential SPECT ligand for sigma receptors. This compound showed an affinity of 0.54 nM ([3H](+)-3-PPP) comparable with the parent compound 2 (Ki = 0.34 nM, [3H](+)-3-PPP). Ligand 8 exhibited a similar potency against [3H](+)-pentazocine. The third class of high-affinity sigma receptor ligands was rationalized based on rearrangement of the bonds in ethylenediamine 2 to give 1-[2-(3,4-dichlorophenyl)-1-ethyl]-4-(1-propyl)piperazine (3). This compound exhibited very high affinity (Ki = 0.31 nM, [3H](+)-3-PPP) and selectivity for sigma receptors.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0022-2623
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2221-30
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Synthesis and receptor binding properties of fluoro- and iodo-substituted high affinity sigma receptor ligands: identification of potential PET and SPECT sigma receptor imaging agents.
pubmed:affiliation
Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't