title: Syntheses and biological properties of chiral fluoroalkyl quinuclidinyl benzilates.
abstract: Previously, (R)-quinuclidinyl (R)-4-iodobenzilate ((R,R)-IQNB), a muscarinic receptor antagonist, has been labeled with 123I and 125I for use in in vitro and in vivo studies in animals and humans. We have prepared fluoroalkyl analogs of QNB, which are amenable to labeling with 18F, for potential imaging applications with positron emission tomography. The enantiomers of (fluoroalkyl)benzilic acids were prepared via an enantioselective Grignard addition reaction. Subsequent coupling of the enantiomeric (fluoroalkyl)benzilic acid with a selected enantiomer of quinuclidinol provides fluorinated analogs of QNB with known stereochemistry at each of the stereogenic centers. These compounds exhibit different affinities for the muscarinic receptor tissue subtypes in vitro. (R,R)-4-(Fluoromethyl)-QNB, and (R,R)-IQNB, and (R,R)-4-(fluoroethyl)-QNB exhibit selectivity for the M1 subtype, and (R,S)-4-(fluoromethyl)-QNB exhibits selectivity for the M2 subtype.
authors.affiliation: Positron Emission Tomography Department, Warren Grant Magnusen Clinical Center, National Institutes of Health, Bethesda, Maryland 20892-1180, USA.
authors.forename: D O
authors.initials: DO
authors.lastname: Kiesewetter
authors.forename: J V
authors.initials: JV
authors.lastname: Silverton
authors.forename: W C
authors.initials: WC
authors.lastname: Eckelman
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D005461:Fluorine / Q000737:chemistry*; D006168:Guinea Pigs; D015394:Molecular Structure; D011813:Quinuclidinyl Benzilate / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D005461:Fluorine; D011813:Quinuclidinyl Benzilate