5-Hexenoic acid, 4,6,6-trichloro-3,3-dimethyl-, methyl ester → 2(3H)-Furanone, 5-(2,2-dichloroethenyl)dihydro-4,4-dimethyl-

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Reaction Steps

The procedure of Example 11 was repeated except that a mixture of 26.0 parts of methyl 3,3-dimethyl-4,6,6-trichloro-5-hexenoate and 26.0 parts of methyl 3,3-dimethyl-6,6,6-trichloro-4-hexenoate (mole ratio=1:1) was used in lieu of methyl 3,3-dimethyl-4,6,6-trichloro-5-hexenoate to obtain 37.9 parts of methyl 2,2-dimethyl-3-(2',2'-dichlorovinyl) cyclopropanecarboxylate (yield 85% based on starting material; cis/trans ratio=29:71) and 4.6 parts of 3,3-dimethyl-4-(2',2'-dichlorovinyl)-4-butanolide (yield 11% based on starting material). The latter compound 3,3-dimethyl-4-(2',2'-dichlorovinyl)-4-butanolide (4.6 parts) was treated with 5.0 parts of a methanolic solution of hydrogen chloride (concentration of hydrogen chloride: about 50%) to obtain 5.5 parts of methyl 3,3-dimethyl-4,6,6-trichloro-5-hexenoate (yield 96% based on 3,3-dimethyl-4-(2',2'-dichlorovinyl)-4-butanolide).

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