Synthesis of (<i>E</i>)- and (<i>Z</i>)-isomers of ethyl 1-(3-chloroprop-2-en-1-yl)-2-oxocyclopentanecarboxylate
A synthesis of ( E )- and ( Z )-isomers of ethyl 1-(3-chloroprop-2-en-1-yl]-2-oxocyclopentanecar-boxylate, perspective synthones of biologically active compounds based on alkylation of ethyl 2-oxocyclopentanecarboxylate by individual isomers of 1,3-dichloropropene. The allylation of ethyl 2-oxocyclopentanecarboxylate by ( E )- and ( Z )-isomers of 1,3-dichloropropene in phase-transfer catalysis conditions in the presence of K<sub>2</sub>CO<sub>3</sub> afforded the corresponding ( E )- and ( Z )-isomers of ethyl 1-(3-chloroprop-2-en-1-yl)-2-oxocyclopentanecarboxylate in 84 and 78% yields. Thus the isomerization of double bond is not practically observed.