Terminal Acetylenic Iminium Salts – Synthesis and Reactivity

Abstract

Various types of terminal acetylenic iminium triflates (propyne iminium salts) featuring a ketiminium or an aldiminium group have been prepared for the first time by protiodesilylation of the corresponding trimethylsilyl‐substituted acetylenic iminium salts using triflic acid and catalytic silver(I) triflate. The high reactivity of the terminal C,C‐triple bond is documented herein by the facile Michael addition of nucleophiles and the exceptionally high dienophilic reactivity in Diels‐Alder reactions.