S. Shimada, Y. Hashimoto, T. Nagashima
1993
Citations
0
Influential Citations
25
Citations
Journal
Tetrahedron
Abstract
Abstract The reaction of 3-alkyl-2,2-dialkoxycyclopropanecarboxylic esters 1d–i with symmetrical ketones and formaldehyde was investigated. Cyclopropanes 1d–i react with symmetrical ketones and formaldehyde in the presence of TiCl 4 to give cis -2,3-substituted-γ-lactones in good yields with high diastereoselectivity. In the reaction of 3-ethylcyclopropane 1d , the reaction conditions hardly influenced the diastereoselectivity. Regarding the reaction of 3-methylcyclopropane 1f , however, the effect of the reaction conditions, especially the solvent, on the diastereoselectivity was observed. High chemoselectivity was also observed for the reaction of 1d with 1,4-cyclohexanedione mono -ethylene acetal ( 24 ). The isomerization of cis -γ-lactones by treatment with NaOEt in EtOH gives trans -isomers in good yields.