Alkenyl copper reagents—26 : Carbocupration of alkynes by organocopper reagents bearing a protected hydroxy or thiol function

Halohydrins, protected as ethers, acetals or chloro-magnesium alcoholates are sequentially transformed into the Li or Mg reagents and then into copper or cuprate derivatives. Addition to acetylene or propyne is discussed according to various parameters. The alkenyl copper or cuprate species, thus obtained, may react further with various electrophiles, leading to difunctionalized alkenes.