Abstract
A-Li shuffle: Experimental and computational data are employed to elucidate the mechanistic aspects of the 1,3-lithium shift occurring in the allenyllithium complexes derived from 1-aryl-1-alkynes. A central role is shown to be played by proton donors, resulting in the in situ formation of a transient allene. This highlights the role of water in the reaction mechanism and explains the disconcerting non-reproducibility of proton-free reaction procedures.