The diverse and high reactivity of the CC bond and the unusually high CH-acidity of monosubstituted acetylenes has determined an unabated interest on 1-alkynes for many years. 1., 2., 3. and 4. The CCH moiety is susceptible of nucleophilic, electrophilic, radical and cycloaddition reactions, and can be used both for functionalizing and building up C–C bonds. In fact, terminal acetylenes are very important key-compounds in the widely applied Mannich, 5 Hay, 6 ...