CuI-Catalyzed Synthesis of Functionalized Terminal Allenes from 1-Alkynes

Relative to our original protocol that uses CuI (0.5 equiv.), paraformaldehyde (2.5 equiv.), and dicyclohexylamine (1.8 equiv.), a facile and efficient protocol for the gram-scale synthesis of functionalized terminal allenes by using CuI (7.5-10 mol-%), paraformaldehyde (1.6 equiv.), and diisopropylamine (1.4 equiv.) has been developed. This method accommodates different functional groups such as hydroxy or carbonyl, and it also performed well in the synthesis of allenylamides and 2,3-butadien-1-ol.