A convenient one-pot process has been developed for conversion of an aldehyde to an arylthionium ion (eg, Schemes IV and V), which can be trapped by a nucleophilic alkene. The stereochemistry of the reactions of such chiral and prochiral arylthionium ions with achiral and prochiral nucleophilic alkenes has been studied. The major adducts are those predicted by qualitative application of the Cram-Felkin rule. Quantitatively, however, the ...
