In the reaction in scheme 1 the alkyne proton of ethyl propiolate is deprotonated by n-butyllithium at -78 °C to form lithium ethyl propiolate to which cyclopentanone is added forming a lithium alkoxide.
One such azide reactions is the 3+2 cycloaddition reaction with alkyne, but the reaction requires high temperature and often gives mixtures of regioisomers.
The common and simplest approach to make vinyl iodide is addition of one equivalent HI to alkyne.