be postulated such an interaction cannot explain the similar ic 50 values of 2c and 1d the presence of the additional chlorine atom on the vinyl group of 2d further increases binding affinity doubling the potency of 2d relative to 2c accordingly it is unlikely that hydrogen bonding interactions are operative in the binding of cocaine to its recognition site on the dopamine transporter the invention will be further described by reference to the following detailed examples wherein tetrahydrofuran and diethyl ether were distilled from sodium benzophenone ketyl prior to use toluene was distilled from calcium hydride prior to use methylene chloride was distilled from calcium hydride and stored over 4a molecular sieves triethylamine and pyridine were distilled from calcium hydride and stored over potassium hydroxide pellets solvents used for extraction and chromatography were purchased in 5 gal drums redistilled from an all glass apparatus and stored in glass bottles silica gel 60 merck 70 230 mesh astm or 230 400 mesh astm for flash chromatography was used for column chromatography other reagents were used as supplied or purified as noted all reactions were carried out in oven or flame dried glassware under an argon atmosphere balloon filled with magnetic stirring unless noted otherwise solutions and liquids were delivered by syringe through rubber septa brine refers to a saturated sodium chloride solution infrared spectra were recorded on a mattson galaxy 2020 spectrometer 1 h nmr spectra were taken at 300 mhz bruker ac 300 in cdcl 3 13 c nmr spectra were taken.