0 an unsaturated compound of hydrogen and carbon (= one that does not contain the greatest possible number of hydrogen atoms) that has at least one triple bond, for example acetylene --
The conjugated alkyne is reduced to the methyl ester.
The most problematic side products of the reaction are due to cyclotetramerization (leading to cyclooctatetraenes) and alkyne dimerization (leading to enynes).
Molecules called ene-diynes feature a ring containing an alkene (ene) between two alkyne groups (diyne).
It is composed of both alkyne and alkene groups.
Alkenylalanes, which are easily synthesized with complete stereocontrol through alkyne hydroalumination, transfer the alkenyl unit to a variety of electrophiles.
The proton transfer leads to intermediate 4, which undergoes the key fragmentation to alkyne (6) and the corresponding carbonyl compound (7).
In the uncatalysed reaction the alkyne remains a poor electrophile.
In the first step of this reaction, a metal acetylide is formed by reaction of the terminal alkyne with the copper salt.
