Wikipedia
Carbometalation
Carbometalation is an organometallic reaction involving the nucleophilic addition to alkenes and alkynes of a diverse range of organometallic reagents such as organolithium compounds, organocopper compounds and Grignard reagents according to the following general alkyne scheme:
The addition can yield the cis or trans isomer and with unsymmetrical alkynes the organometallic compound can add in two different way thus control of regioselectivity is important.
In a follow-up step the sensitive metalalkenyl group is replaced by an electrophile E.