Addition to 2,4-Dienes. Halogenation of Ethyl ... - ACS Publications

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The addition of chlorine and bromine to ethyl sorbate (la) gave 1,2- and 1,a-dihalo products ... more stereospecific (80%) than the 1,Z-addition of chlorine.

J . Org. Chem., Vol. 42, No. 12, 1977 2141

Halogenation of Ethyl Sorbate OCHz), 6.70 (m, 1, olefinic H). Anal. Calcd for CllH1603: C, 67.32; H, 8.22. Found: C, 67.11; H, 8.26. 4-Acetonyl-2-cyclohexenone(15c) and 2-Acetenyl-2-cyclohexenone (16c). A combination of 1.00 g of a 8c-9c mixture and 15 mL of 2 N hydrochloric acid in 15 mL of ether was stirred at 25 "C for 1 h. The ether layer was separated, the aqueous solution saturated with sodium chloride and extracted with ether, and the combined organic solutions worked up as for 15a above. Preparative TLC of the crude product, 750 mg, and elution with 4:l ether-hexane yielded 110 mg of diketone 16c [IR C=O 1710 (s), 1670 cm-I (s); 'H NMR d 2.17 (s, 3, Me), 3.25 (broad 13, 2, COCHz), 6.78 (t, 1, J = 3 Hz, H-3); mass spectrum m / e 152 (M+),54,37 (base); exact mass m / e 152.0837 (calcd for CgH1202, 152.0833)] and 565 mg of diketone 15c [IR C=O 1715 (s),1675 (s),C=C 1616 cm-1 (w); 1H NMR d 2.22 (s, 3, Me), 5.95 (dd, 1, J = 10,2 Hz, H-2), 6.81 (ddd, 1,J = 10,3,1Hz, H-3);mass spectrum m / e 152 (M+),95, 55, 413 (base); exact mass m / e 152.0830 (calcd for CgH1202, 152.0836Jl. 4-Acetonyl-4-methyl-2-cyclohexenone (15d) and 2-Acetonyl-4-methyl-2-cyclohexenone(16d). A combination of 1.30 g of a 8d-9d mixture and 25 mL of 2 N hydrochloric acid in 25 mL of ether was stirred at 25 "C for 1h. Workup as for 15c-16c above yielded 850 mg of oil, bp 70 "C (0.15 Torr), whose preparative GPC (180 "C) yielded 477 mg of a mixture of 16d and its isomer, 2-acetonyl-4methyl-3-cyclohexenone (16d') [IO min retention time; IR C=O 1710 (s),1675 cm-I (s);lH NMR 6 1.16 (d,

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