Methods, compositions, and systems related to preparing gaseous .sup.18F-compounds for use in radiolabeling positron emission tomography (PET) tracer precursor compounds are disclosed. [.sup.18F]fluoride ions produced by conventional methods are converted by reaction with an acid anhydride having the formula: ##STR00001##
to a gaseous .sup.18F-compound having the formula: ##STR00002##
wherein each R is independently a substituted or unsubstituted, straight chain or branched C.sub.1-C.sub.4 alkyl group. The gaseous .sup.18F-compounds, which also can be readily trapped on solid-phase extraction media or in organic solvents such as acetonitrile, provide an alternative source of [.sup.18F]fluoride for use in the nucleophilic substitution reactions that are used to synthesize a large number of .sup.18F-labeled PET imaging tracers, including 2-[.sup.18F]fluoro-2-deoxyglucose (FDG).

Methods, compositions, and systems related to preparing gaseous .sup.18F-compounds for use in radiolabeling positron emission tomography (PET) tracer precursor compounds are disclosed. [.sup.18F]fluoride ions produced by conventional methods are converted by reaction with an acid anhydride having the formula: ##STR00001##
to a gaseous .sup.18F-compound having the formula: ##STR00002##
wherein each R is independently a substituted or unsubstituted, straight chain or branched C.sub.1-C.sub.4 alkyl group. The gaseous .sup.18F-compounds, which also can be readily trapped on solid-phase extraction media or in organic solvents such as acetonitrile, provide an alternative source of [.sup.18F]fluoride for use in the nucleophilic substitution reactions that are used to synthesize a large number of .sup.18F-labeled PET imaging tracers, including 2-[.sup.18F]fluoro-2-deoxyglucose (FDG).

The present invention provides compounds of the formula:

##STR00001##

that are 5-HT3 receptor antagonists and are therefore useful for the treatment of diseases treatable by inhibition of 5-HT3 receptor such as emesis, pain, drug addiction, neurodegenerative and psychiatric disorders, and GI disorders. Also provided are pharmaceutical compositions containing such compounds and processes for preparing such compounds.

The present invention provides compounds of the formula:

##STR00001##

that are 5-HT3 receptor antagonists and are therefore useful for the treatment of diseases treatable by inhibition of 5-HT3 receptor such as emesis, pain, drug addiction, neurodegenerative and psychiatric disorders, and GI disorders. Also provided are pharmaceutical compositions containing such compounds and processes for preparing such compounds.

The present invention provides 5-HT3 receptor antagonists of Formula (I):

##STR00001##

which are useful for the treatment of diseases treatable by inhibition of 5-HT3 receptor such as emesis, pain, drug addiction, neurodegenerative and psychiatric disorders, and GI disorders. Also provided are pharmaceutical compositions containing such compounds and processes for preparing such compounds.

The present invention provides 5-HT3 receptor antagonists of Formula (I):

##STR00001##

which are useful for the treatment of diseases treatable by inhibition of 5-HT3 receptor such as emesis, pain, drug addiction, neurodegenerative and psychiatric disorders, and GI disorders. Also provided are pharmaceutical compositions containing such compounds and processes for preparing such compounds.

The present invention provides compounds of the formula: ##STR00001##
that are 5HT3 receptor antagonists and are therefore useful for the treatment of diseases treatable by inhibition of 5HT3 receptor such as emesis, pain, drug addiction, neurodegenerative and psychiatric disorders, and GI disorders. Also provided are pharmaceutical compositions containing such compounds and processes for preparing such compounds.

The present invention provides compounds of the formula: ##STR00001##
that are 5HT3 receptor antagonists and are therefore useful for the treatment of diseases treatable by inhibition of 5HT3 receptor such as emesis, pain, drug addiction, neurodegenerative and psychiatric disorders, and GI disorders. Also provided are pharmaceutical compositions containing such compounds and processes for preparing such compounds.

Methods, compositions, and systems related to preparing gaseous .sup.18F-compounds for use in radiolabeling positron emission tomography (PET) tracer precursor compounds are disclosed. [.sup.18F]fluoride ions produced by conventional methods are converted by reaction with an acid anhydride having the formula: to a gaseous .sup.18F-compound having the formula: wherein each R is independently a substituted or unsubstituted, straight chain or branched CrC4 alkyl group. The resulting gaseous .sup.18F-compounds can be produced and stored in close proximity to the production location of the [.sup.18F]fluoride ions (such as within a cyclotron vault), or easily and efficiently transported long distances with minimal loss of-radioactivity. The gaseous .sup.18F-compounds, which also can be readily trapped on solid-phase extraction media or in organic solvents such as acetonitrile, provide an alternative source of [.sup.18F]fluoride for use in the nucleophilic substitution reactions that are used to synthesize a large number of .sup.18F-labeled PET imaging tracers, including 2-[.sup.18F]fluoro-2-deoxyglucose (FDG).

##STR00001##

Methods, compositions, and systems related to preparing gaseous .sup.18F-compounds for use in radiolabeling positron emission tomography (PET) tracer precursor compounds are disclosed. [.sup.18F]fluoride ions produced by conventional methods are converted by reaction with an acid anhydride having the formula: to a gaseous .sup.18F-compound having the formula: wherein each R is independently a substituted or unsubstituted, straight chain or branched CrC4 alkyl group. The resulting gaseous .sup.18F-compounds can be produced and stored in close proximity to the production location of the [.sup.18F]fluoride ions (such as within a cyclotron vault), or easily and efficiently transported long distances with minimal loss of-radioactivity. The gaseous .sup.18F-compounds, which also can be readily trapped on solid-phase extraction media or in organic solvents such as acetonitrile, provide an alternative source of [.sup.18F]fluoride for use in the nucleophilic substitution reactions that are used to synthesize a large number of .sup.18F-labeled PET imaging tracers, including 2-[.sup.18F]fluoro-2-deoxyglucose (FDG).

##STR00001##