RECENT DEVELOPMENTS IN IMINIUM SALT CHEMI STRY

Iminium salts are of continuing interest as versatile building blocks in organic synthesis. This progress report from different laboratories highlights some current research activities in iminium salt chemistry . Several contributions focus on novel synthetic applications of isola ble, functionalized iminium systems such as alpha, beta-unsaturated im inium salts (e.g. vinamidinium, 3-trifloxy, 3-chloro-, 3-isocyanato- a nd 3-thiopropene iminium, as well as propyne iminium salts), furthermo re on phosgene iminium chloride and trifluoromethyl-substituted iminiu m salts. Iminium intermediates occur in various synthetic transformati ons; for example, cyclopropane iminium ions are intermediates in nucle ophilic substitution reactions at bicyclic aminocyclopropanes. Also re ported is the synthesis of a variety of novel orthoamides and their us e as synthetic building blocks. Research directed to the application o f vinamidinium salts in materials science is also presented.