New stereoselective reactions to form amido alkyl c-n and vinyl triflate c-o bonds via carbocation intermediates & ultrafast silicon fluorination methodologies for applications in pet imaging

We report here the development of a Lewis acid catalyzed method for the dehydrative
coupling of cyclic alcohols and nitriles to form amides with retention of configuration.
By contrast, the formation of amides by nitrile trapping of carbocations (Ritter reaction)
usually affords racemic product. The present reaction was accomplished by first
converting alcohol starting materials to their corresponding chlorosulfites in situ. Even
after an extensive search, only copper (II) salts were able to produce the desired
conversion of these chlorosulfites to amides though with low catalytic turnover.
Improving the turnover without deteriorating the stereochemical outcome was eventually
accomplished by a careful selection of the reagent addition sequence and through the
removal of gaseous byproducts. This Ritter-like coupling reaction proceeds in good
yields with secondary cyclic alcohols under mild conditions. The stereochemical outcome likely due to fast nucleophilic capture of a non-planar carbocations (hyperconjomers)
stabilized by ring hyperconjugation.