An atom-economical and solvent-free ytterbium(III) triflate promoted,
zinc(II) chloride catalyzed Conia-ene method has been developed
for the construction of five- to six-membered-ring carbocycles.
In the presence of zinc(II) chloride and ytterbium(III) triflate,
a variety of linear β-alkynic β-keto esters and β-alkynic β-diketones
were cyclized under neat conditions in moderate to good yields.
It is noteworthy that the selectivity toward five- or six-membered-ring
carbocycles depends on substituents at the terminal alkynes.
zinc(II) chloride - ytterbium(III) triflate - Conia-ene
reaction - linear β-alkynic β-dicarbonyl - carbocycle