| abstract |
(2,2-Disubstituted vinyl)-γ-butyrolactones of the formula: ##STR1## in which R 1 and R 2 are hydrogen or C 1 -C 6 alkyl, preferably methyl, n R 3 and R 4 are hydrogen, C 1 -C 6 alkyl, preferably methyl, or halogen, or, together with the carbon atom to which they are attached, form a cycloalkyl group, and n R 5 is C 1 -C 6 alkyl, n are prepared by condensing an epoxide of the formula: ##STR2## with a malonic acid ester of the formula: ##STR3## in a basic medium. The butyrolactones of formula I are valuable intermediates for the synthesis of synthetic pyrethroids having insecticidal activity. |