A series of heterosubstitued alkynes was successfully submitted to the intramolecularcarbolithiation of their triple bond. We show that the addition is stereoselective because of the control exerted by the terminal substituent X on the geometry of the transition state. A complementary DFT study suggests that the addition is anti when a strong Li–X interaction occurs.
Intramolecular (3+2) cycloaddition reactions involving benzyne and ynamides as three-atom components have been accomplished through the utilization of benzyne precursors having a linking functionality. The ambivalent nature of the intermediate indolium ylide, which exhibits both nucleophilic and electrophilic properties at its C2 atom, is thus brought to light in this approach.